Fender designed and built more than one transitional, non reverb blackface combo amp that would soon acquire reverb and a new name, including relatively small numbers of blackface Princetons, 4×10 Concerts, 1×12 Vibrolux and 1×15 Pros. We acquired a 1×15 blackface Pro, and while it ultimately proved to be an extraordinary exceptional amp, we were also reminded of the potential pitfalls that exist when buying old amps sight-unseen, as well as the potential rewards.
We found the ’64 Pro listed on eBay and bout it from a dealer after requesting a detailed photo of the chassis and circuit. Proudly described as “the best amp in the store, “the rare ’64 blackface Pro is essentially a blackface Vibroverb without the “verb.” Do we have your attention yet? Three caps had been replaced, the original baffleboard had been professionally converted to plywood with the original grill cloth remaining intact, and an on/off pot had been installed for the tremolo intensity control that bypassed the tremolo circuit when rolled to “1” with a click, adding gain that would otherwise be missing in the Vibrato channel. We pulled the JJ power tubes and assorted Russian pre-amp tubes and replaced them with lightly used,“test new” RCAs from our stash, rebiased the amp and fired up the Pro….
Sounded like shit. We had been here before with a dead-mint ’64 Vibroverb bought years ago that had passed through a certain amp guru’s hands in Pflugerville, Texas.How could a vintage Fender sound so bad we wondered? Turned out that the value of the bright cap on the Vibrato channel had been changed on the Vibroverb, rendering a thin, scalding tone that would have given Ed Jahns fits, as it did us. Changing the bright cap back to spec immediately restored the Vibroverb to its rightful pace in history, but the Pro had other problems….
The baffleboard swap and added switch on the tremolo intensity control were clues that someone had also spent time troubleshooting the amp, probably trying to detect the cause of the Pro’s weak output, thin tone and curiously harsh edgy distortion. The amp just didn’t sound right. We pulled the original, reconed Jensen C15N dating to 1964 and subbed in an Eminence Legend, but the Pro still sounded choked-off, linear and wrong, so it was off to Jeff at Bakos Amp works on the Friday afternoon before Memorial Day weekend in a frog-chokin’ Georgia thunderstorm. When the going gets weird, the weird turn pro…..Now, this is the difference between someone who really knows his craft and a hack….Jeff plugged his bench guitar into the Pro, hit a couple of chords, issued a single grunt of displeasure and caustically observed, “Something is definitely fucked up.” With the chassis on the bench, Jeff scowled at the choppy sine wave the amp produced on his scope as he checked voltages with his multimeter. “I think the output transformer is going down slow—it measures 11 volts and it should be reading 16….” He clipped in a substitute OT from a stout old Fisher hi-fi, plugged in and hit a chord… “That’s closer to what it’s supposed to sound lie….” And sure enough, the missing lows and mids were present, the raspy treble tones were subdued, and for the moment, the Pro showed promise. We called Paul at Mercury Magnetics and ordered a black-face Pro Tone Clone replacement trans-former, shut it down and wished each other a good holiday. A week later the Mercury Magnetics replacement output transformer had arrived. Jeff wired it up, and then turned his attention o three silver mica caps that had replaced the original ceramic caps in the phase inverter and tone circuits. Jeff: “Somebody probably read an article about how these would bring the high end up, but I prefer the ceramics—always have. Besides the effect of the voltage from the old output transformer being low, these silver mica caps were contributing to that brittle tone we were hearing. They are the wrong value, and they changed the entire sound of the amp.” Jeff pulled all three silver mica caps and replaced them with the correct ceramic disc caps, and since an on/off switch had already been installed for the tremolo, we mounted the 25K mid range pot in the back panel hole for the extension speaker jack. With the Pro now thoroughly put right and the midrange pot added, Jeff hit a few chords, moved the EQ and volume settings around a bit in both channels, smiled and said, “That sounds really good. Yeah, that’s it.”
Back in our music room, the final step was to re-bias the Proat 34mA with an AmperexGZ34 rectifier and our last pair of vintage RCA black plate 6L6s, which in unused, new old stock condition have soared to $400/pair. The re-labeled Tube NOS Phillips JAN 6L6 WGBs we had tried sounded good—but the smooth warmth, exceptional musicality and deep harmonic content of the RCAs just can’t be beat, and it is a difference you can definitely hear. Smoke ’em if you got ’em….
We lit up the Pro with the ’63Fender Reverb unit and reverently smiled at the jaw-dropping tones pouring from the big Eminence Legend 15. Imagine the sound of a slightly kinder, warmer sounding 40 watt Super Reverb void of the sharp, penetrating treble presence that has sooften left our ears ringing for hours after a tumble with a blackface Super. The sound of the ’64 Pro is all Fender, with solid bass that doesn’t fall apart at high volume as the smaller blackface combos can,sweet, singing treble tones, and now… a mid range control that can gradually push the amp beyond its original, clear and liquid “scooped” mid range voice to an exceptionally thick, “mid-Atlantic” roar that unleashes heavy sustain and rich, musical distortion as only a Fender can. The Pro brilliantly complements every guitar we own, producing the essence of classic Stratocaster, Tele, P90 and humbucker tones with clarity, depth and lush fidelity that literally fills the room. Yes, there are different and equally worthy tones to be had from the British classics,but we have never heard a more beautiful sounding or versatile Fender amp—one that can range from crystalline, blackface clarity to the full burn of an early blonde Fender Bassman at much friendlier volume levels. The Pro can get plenty loud, but it’s a loud that doesn’t kill you in the style of a Showman, Twin or a Super Reverb.
The irony in this unexpected discovery has not escaped us,and perhaps the weight of it is now becoming clear to you, too. This project did not begin well, and we confess to experiencing some remorse when the Pro arrived with a few bad mods, weak and thin from the original output transformer going down, and generally just sounding very wrong. Our dismay was soon displaced by genuine enthusiasm; however, as we were reminded that this is indeed what the quest for tone is all about it. We’ve acquired absolutely bone stock amps in perfect working condition that just couldn’t tote the note, so why should we expect to buy a 44 year old amp that’s been played without it needing a little repair and restoration work? The end entirely justifies the means.
Having finally experienced the Pro’s singular, exceptional sound, we wondered what had caused it to be relegated to such obscurity among all the Fender black face amps. Like the Vibrasonic and Vibroverb, perhaps it was doomed by the presence of the single 15” speaker. Like the Pro, the blackface Vibroverb 1×15 was produced for less than a year, and with the introduction of the 2x12Pro Reverb in 1965, Fender would no longer produce a 1×15 combo until the introduction of the silver face Vibrosonic in 1972. Yet, the earlier 1×16 Pros had been Fender’s flagship amps during much of the tweed era, and in 1960 the 1×15 brown Pro ranked second only to the1x16 Vibrasonic in the Fender catalog. Somewhere along the way, the 1×15 combo had clearly fallen out of favor with Fender, guitarists, or both, and given the short life span of the Vibroverb, even the addition of reverb couldn’t save it.
Twenty years later, Stevie Ray Vaughan elevated the Vibroverb to hall of fame status, otherwise, the 1×15 com-bos seem to have been perceived as “uncool” for anything bug jazz and blues, as if wearing a jacket and tie were required to play them. The Pro is a great blues amp, but it’s also a great rocker, and equally well-suited for jazz, pop and country. With far more clean head room and power than any tweed Pro and much stronger distortion, sustain and dynamic character than a brown Pro, the blackface Pro reflects Fender’s ongoing pursuit of more powerful, cleaner sounding amps, but unlike the black face Bandmaster, Tremolux and Showman, and Pro can really rock the house cranked. We suspect it’s a single 15 and missing ’verb that throws people off today, yet in’64 Pro shares its DNA with the ’64 Bassman and all the highly prized blackface combo amps, including the Deluxe Reverb, Vibrolux Reverb, Super Reverb and the heavily prized and hyped Vibroverb.
The contrast between the Vibroverb’s Holy Grail status versus the lowly blackface Pro simply underscores how easily we can be blown off course by what isn’t hyped on the Internet or in print, and by the powerful logic that suggests if anything 44 years old is truly noteworthy, “we” would already know about it. Well, apparently “they” don’t. But you do. Blackface Pros can be found for $1 500–$2,000,with originality and overall condition driving prices accordingly. Like the Deluxe, we wouldn’t buy one that has had all the blue molded capacitors or Allen-Bradley resistors replaced, but the transformers available today from Mercury will sound every bit as good or better than the originals, and as we have said so many times in the past,the Eminence Legend 15 is spectacular. Add some good,current production or NOS tubes and you will have been delivered to a place well beyond the common man’s limp and shriveled imagination. Now Quest forth….
In late 2009 I had the opportunity to talk with Sergio Hamernik about the history of the Mercury Magnetics, how he became involved in making transformers for guitar amplifiers, and the difference a high quality transformer can make on your tone.
How did Mercury get its start?
The company’s roots date back to the early ’50s. Mercury was started by an old General Electrics transformer engineer who was working there pre-World War II. He then went on to do a bunch of design work for the war effort. And in the early ’50s, hung a shingle and became self-employed.
The name “Mercury” came out of his passion for Mercury cars, he always drove a Mercury since the late ’40s — he loved those cars — and eventually moved from the East Coast to the West Coast where he found that there was a lot of military and aerospace work. A booming economy in the early ’50s gave him a lot of business.
I met him in the 1970s when I was an engineering student and an audio enthusiast. Back then the electronics world was well into its solid-state “evolution,” and interest in tube gear was quickly disappearing. Not for me, however. I found myself in demand as a guy who knew about those “old things”; not only the math, formulas and specifications but I also had the “ears.” I could fix and keep the old gear running. So, I worked as a hired gun for a bunch of studio heads and pro musicians.
Typically when an amp’s output transformer blew. No one seemed to know any better so it was just swapped by whatever “factory” replacement or an off-the-shelf “equivalent” catalog transformer was handy. The invariable result was that the amp’s characteristic sound was gone. And no matter what resistors, caps or tubes were used, it could not be rescued or returned to its original sound. It was the transformers, it turned out, that were the key. The problem was coming up with a way to remedy the blown transformer replacement or repair that wouldn’t alter its tone.
To further complicate things, most transformer people I dealt with just didn’t want to bother with the music industry. For the most part the established electronics industry considered the needs and opinions of the audio and MI (Music Industry) communities as subjective, run by kooks, and occupied by people who didn’t know what they are doing. Audio and MI had always been considered the illegitimate stepchildren to the rest of the industry.
Out of pure necessity I had to got involved with transformer design and manufacture. As a customer of Mercury, they had built many custom transformers to my specifications — although we had many heated, on-going debates on the subject because the company owner hated audio! He never did understand what made guitar amp transformers tick, or how musicians thought and reacted to them.
That aside, he pestered me for almost a decade to take over the company because he felt I was the only one qualified. Eventually I did, and that was when Mercury got serious about the guitar amp connection. Sometimes you end up becoming an expert at something when no one else wants to do the job.
By the time I took the helm we were developing a really good and workable understanding of the relationship of transformer design to decent tone and how amps should behave. And around 1980 we began the long and arduous task of collecting and cataloging transformer specifications for every vintage amp, from all over the world. The deeper we dug, the more apparent it became that there were all kinds of factors that no one had previously suspected that affected guitar tone. And likewise, no one seemed to be paying attention to such things.
In turn, we invented proprietary technologies to aid this work. Even after three decades, we’re still innovating and discovering new things. From that fundamental research came our now famous ToneClone series, and later the Axiom line, which is probably the most significant advancement in toneful guitar amp transformer designs since the ’50s. Both product lines, we’re proud to say, have distinctly different niches in the annals of guitar amp tone.
We’ve not only cured the old transformer tone issues, but made it possible for musicians to upgrade their existing amps. And we’ve also made it possible for amp builders to reproduce amps of the same or better grade than even the most outstanding vintage amps of the past.
When did you become involved with making transformers for guitar amplifiers?
Back in the ’70s I worked for people on a one-to-one basis, usually under confidential arrangements, with certain rock stars that just didn’t want to be bothered by their names being flaunted around. What they want was their amps running right for recording, projects, touring, etc.
The problem was that when technicians would fix the amps they’d often loose their tone. It turned out that the culprit was the replaced output transformers. A changed output transformer would completely alter the character of the amplifier. So as I was the guy doing most of the work to resolve this issue, this expertise was brought to Mercury where we began a special division to cater to the guitar heroes.
Word got around rather quickly that Mercury was able to repair, rewind, and restore the original transformers and it just grew from there. The whole “Tone Clone” thing came from artists who had these amazing irreplaceable amps, amps that often made recording history. They didn’t want to take these amps on tour. So we came up with the innovative idea of cloning their original transformers that they’d fallen in love with. With the clones we could now easily make, for the first time ever, several identical amps for them. Or they would assign their techs to drop-in the cloned transformers so they would have, for example, six amps that would all sound the same as that first perfect amp.
These artists could now go on tour and not worry about breakdowns or theft, and keep their prized-originals back at home.
I worked with Ken Fisher, the whole Trainwreck thing, and a lot of the early boutique guys — and still do with Alexander Dumble. They preferred to keep things confidential and not let too many people know who their sources were because there were so few transformer designers that catered to the guitar amp market.
There was also a slow-but-steady dumbing-down occurring in audio and all that had been the post World War II momentum. Many of the ex-military components we’d been using were high tolerance parts, with mil-spec formulations of iron and copper and so on, that had been used to win the war effort. During the ’50s and ’60s we enjoyed the benefits of those high quality components at surplus prices. But by the late ’70s, and definitely in the ’80s, steel manufacturers started to change recipes to make the iron and other materials much more affordable.
You can hear the differences between a late ’60s Marshall, a late ’80s Marshall, and a Marshall today. A good listen will really help you to understand what changes took place. Unfortunately they made so many of those changes more out of economic considerations than anything else. The amps were loud but they seemed to be losing sight of the fact that their tone was disappearing — the “recipes” had been changed.
In addition to many other factors, the iron that Mercury uses is custom-formulated specifically for us. We buy enough of it to be able to dictate the exact recipe from the foundries. And all of our iron is literally from American ore processed right here in the USA. 100% American made to the original specs. Are there drawbacks? Well, some of the iron rusts more easily, but that’s actually a good thing because rust is a natural insulator. But the opposite is also true. When you see a modern transformer with a silvery or a shiny core just know that they aren’t worth a damn when it comes to tone.
Can you tell us more about guitar amp transformer history?
Here’s an amusing anecdote that may help explain our case for guitar amp transformers: There’s a great deal of documentation, from back in the mid-’50s, where engineers, and other technical people, were writing really scathing reports on how awful the transformers were in the audio industry. Those darn transformers! When tubes were plugged into them there was a tendency to distort! And they couldn’t have any of that! Likewise with harmonic distortion — especially even-order harmonic distortion.
Many amp builders, techs and players, today, don’t understand that tubes were originally designed to run dead clean, linear, and be efficient voltage amplifiers. That the tone we’ve all come to know and love is caused by the transformers literally “irritating” the tubes into distortion.
Which is, of course, the whole point of what we are looking for in guitar amps. Back in the ’50s, they were fighting to get rid of those nasty distortion tonal characteristics. Now we embrace them. But that was audio – guitar amps were still in they’re infancy and yet to be realized. It took a generation or two of innovative musicians to take those “undesirable” tonal characteristics and create music; to work with distortion and make it into something musical.
Ironically, it was that no-distortion engineering mindset that ushered in solid-state, and why it was so openly embraced in the ’60s. It was solid-state electronics that eliminated the output transformer.
In the late ’60s, Vox went to Thomas Organ to have solid-state amps built. They were very proud of this state-of-the-art amplifier. Curiously, I met a few of the musicians from the late ’60s that were sponsored by, and using, those amps. The tone was so awful and unbearable that they used the enclosures but hid their old tube gear inside! As you may already be aware, the vacuum tube industry is alive and well, and we’re still waiting for the solid-state industry to catch up.
Part of the confusion is that musicians assume it’s the tubes that give them their tone. There’s a lot of synergy going on in an amp, and the tubes certainly contribute, but let me illustrate this another way. Did you know that there is what we call “output transformer-less” amplifiers in the HiFi world?
These amps basically parallel a bunch of power tubes together until they get down to 16, 8, or 4 ohms. There is no output transformer, so you literally connect the speaker directly to the tubes. If you ever get the opportunity to do an audio demo with this style of amp, you will find that while it works, it sounds nearly solid-state. The output transformer is what provokes a tube into giving the characteristics that we find desirable as far as tone. Audio engineers didn’t want the tubes to distort, as tubes are basically nothing more than very clean voltage amplifiers. But when you have a reactive element like a transformer, you irritate the tubes into harmonic distortion.
Therefore, the difference between a good and mediocre transformer is based on how it works and syncs with these tubes to produce the kind of tone or distortion we are looking for. It is not as easy as winding some wire around a steel core, if it was then we would not be having this conversation.
How does a Mercury transformer made today compare to the transformers made in the golden age of amps (the ’50s and early ’60s)?
One of the biggest mistakes existing in today’s amplifier community, especially amongst hobbyists and do-it-yourselfers, is to blindly copy every aspect of a vintage amplifier hoping to get a piece of that golden tone. At best, this method still produces very random results. One of the key reasons for this is the often-overlooked missing transformer formula. A builder will fuss around with the tiniest of other details but completely miss how the transformers fit into the equation. In short, get the transformers right, then the rest is much easier. Here’s another look at theses deceptively simple devices:
For vintage-style transformers, Mercury starts by duplicating the transformer design, build errors and all. We use the best grade components like they did in the ’50s and ’60s. We wind every layer and every turn as if it were a circuit in itself. In fact, the diagram on the left shows an output transformer circuit equivalent. Most people would think it is an audio circuit. These things are fairly complex, and all the numbers have to be right in order to get the tone we want as musicians.
We really do follow the recipe to a point. Although we don’t repeat any of the mistakes or inconsistencies that were prevalent, but didn’t affect tone. For example, if you were into Fender tweeds or late-’60s Marshalls. To do this we would literally put the word out to rent or borrow dozens of amplifiers to find the one or two that had the sound, and dismiss the rest. There were typically many inconsistencies as well as “happy accidents” in the best-sounding examples we’ve auditioned. A lot of this has to do with the sloppy tolerances of the original transformers.
For our transformers we extract the best parts and virtues of the original best-of-breed transformers and remove all of the obstacles to tone. Perhaps just as important is that we adopted a “cost is no object” approach, making our transformers equal or better than the originals — and then add consistency. We now have this so finely tuned that if you bought a transformer from us five years ago, and then the same one today, it would sound exactly the same. You don’t want good batches and bad batches, which is precisely what made the original production runs vary so much.
Another issue is the so-called controversy between paper tubes and nylon bobbins. In the vintage years they used both. Some people think that somehow, some magical quality comes from using a paper tube winding form over a nylon bobbin. Tonally it made no difference at all. Paper tubes were widely out of tolerance most of the time because of how they were made. They would wind multiple coils on long sticks then use a saw or blade to cut off the various coils. In order for these long tubes or coils to come off of their winding forms they had to be conical. So this invariably meant that the first coil would be larger in diameter and the last coils smaller. As you can see, it’s easy to see why each of these inconsistently-made bobbins had a greater difference than the material they were made from. And there are other issues that occur over time, like paper has a tendency to disintegrate, collect moisture, etc.
When we switched to using nylon bobbins the tolerances were within 3,000’s of an inch of each other, as opposed to the wildly varying amounts found in paper tubes. If you were ever to take apart a really old transformer (pre-’70s) sometimes you’ll find wood wedges that are jammed between the paper tube and the core because that piece of paper was too wide and too sloppy to fit into the core correctly! They would force a wedge in there so the darn things wouldn’t rattle!
Which method, paper or nylon, made for the best tone? It’s the luck of the draw. We’re fortunate in that we have all these stars as clients who have these amazing-sounding amps. They went through the hassle of culling and choosing and picking the special amps that inspired them. The amps they recorded with. When we analyzed their transformers we sometimes found happy accidents or other little anomalies that would set a transformer apart from already sloppy tolerances of the standard production run.
There are little subtleties and changes from one transformer to another that make a heck of a difference tonally. So when you look online at our list of ToneClones, just know that they are from the hand-picked, best-of-the-best amps of their model and era. We continue this “weeding” process every day — and there’s apparently no end in sight. And that’s why, with some amps, we have several versions — each with its own tonal qualities — and others only a single set to choose from.
We use this process to establish new benchmarks. And you never know, tomorrow a new variant may arrive that totally blows away what we already thought was as good as it could ever get.
It is interesting that you take that approach to upgrading — the never-ending search for better-sounding benchmarks.
There is no real money or glamour in what we do, it is really all born of a passion for music. I come from a musical family, my Mom taught me as a little kid that music was a form of “food.” And that hasn’t changed. Everyone who works at Mercury is just in love with playing and listening to music, and we all believe that there is always some room for improvement or a way to raise the bar somehow.
Back in the ’70s and ’80s there wasn’t really a need for a company that designed and sold transformers to the public, so I stayed away from the general public for as long as I could and really only worked with professionals.
But at some point I realized that it was the average player who was getting ripped-off. Things were getting dumbed-down, the tone is slowly and steadily being vacuumed out of the amps. They were becoming duller-sounding, less interesting and more noisy. So, we decided to formally launch this product line so the average guy could have access to our technology. It takes an extreme amount of labor and effort it takes to build them to this standard. You know, even if someone wanted to buy 1000 transformers we would have to no-bid them because we really don’t have any way of doing things quickly.
Automation isn’t a practical solution. Everything we do is wound by hand, one at a time; it is the only way it can be done. Say you have 100 turns and 10 layers, well that would mean 10 turns per layer — that is how a machine would think of it. But what if a rock legend’s best transformer was 9 turns on one layer, 11 turns on the next, 7 on the next, 3 after that and so on, but the sum total ended up being 100 turns. Sometimes one layer can have a different winding style than the other; sometimes it is non-symmetrical meaning, if it is a push-pull, that one side of the primary doesn’t have the same turns as the other side. If that was the recipe that created the magic, we’d have to duplicate it. It’s just not practical to build machines to do that, so we end up having to do it by hand. It’s the proud old-school craftsmanship way of doing things. Something I think we could see a lot more these days.
We have a reputation for nailing tone. Our Fender transformers don’t sound like Marshalls, they sound like Fenders — and vice versa. In fact, we’ve become the industry’s new standard. If you were going to design or create a tube-based amp, it’s clear that we’re the folks to talk to.
Can you explain how a Mercury transformer can improve an amplifier’s tone and how they outperform the stock transformers found in most amplifiers?
In designing toneful transformers specifically for guitars (and that’s all we’re talking about here, not necessarily transformers for HiFi or any other purpose), the trick is in the magnetic field and how it behaves. The nature and the speed with which the iron reacts to the changing of an alternating current, in an alternating magnetic field, is what makes tone happen.
If you have “slow” iron, you’ll have a dull, non-sparkly sound with no bell tones — no matter what you do with the amp it will always be kind of noisy and fuzzy.
Where others have tried and failed they’ve blindly followed generic transformer formulas without understanding that guitar amps are different animals. They’ve somehow missed that point despite all the evidence to the contrary. The fact is that transformers for guitar amps do not necessarily follow textbook rules.
Indeed, it should probably be noted that we’ve developed a whole new technology around transformer design specifically, and only for the guitar industry. And that these designs are essentially irrelevant to any other use. But Mercury is also in a highly unusual position. Our decades of transformer “vivisection” have revealed all manner of unconventional tips ‘n tricks to us. And we’re now the keepers of this new, but proprietary, technology.
I seriously doubt that we could have done it without the, let’s call it “archeological benefits,” of our observations. Decades of studying the good, the bad and the ugly of guitar amp transformers have revealed a great deal.
Nothing that I have found in the reissue market, transformer-wise, even resembles anything that was made during the “the golden age of tone.” They are unrelated. The inductance, magnetic fields — all of that is just completely different and far removed from the original designs and recipes. So there is no way that a reissue amp is ever going to sound vintage unless they bother putting in the right ingredients.
With our Upgrade Kits, for example we’re trying to show people that we can move forward into new sonic territory from where vintage designs and tone left off. And our Axiom series transformers are the definitive showcase for this technology. Their tone is just amazing.
To push the point even further, we don’t include any “voodoo” parts in our Upgrade Kits. With the exception of the transformers, the Kits use only common, everyday, and off-the-shelf components. And most of our Kits also include a Mini-Choke. When the circuitry is correctly designed a Mini-Choke will make a huge improvement in an amp’s tone because, in terms of its power supply, it changes the way the amp works.
A good guitar amp is only as good as its power supply. If you have a dynamic and moving power supply that reacts to the demands of the audio end you’ll get get great note separation and good bass dynamics. You start to hear chimes and other phenomenon, and even the harmonics between the strings like a “5th note.” What the heck is the “5th note”? In barbershop quartets, if they get their harmonies right, they hear the “5th note” which is basically a harmonic of all four singers. We are doing that with our guitars thanks to distorted amplifiers.
Where did the idea for offering an Upgrade Kit for amplifiers like the Champ “600” and Valve Jr. come from and who designed the Upgrade?
I designed all of the magnetics (the transformers and Mini-Choke) and the general concept behind the Upgrade in league with Allen Cyr from the Amp Exchange. He is one of the most competent, finest amp designers I know of; there are only about five in the world that are true masters of the art — those who really know the math, how to read tone, how to listen to the subtleties of clean and overdriven sounds and tones, design circuits, and understand tube behaviors. As a bonus to those who appreciate this kind of thing, we always try to throw in some interesting tweaks and tricks that are unorthodox.
The idea is to spark some interest and perhaps get more people involved in tube-based amp tone and evolution. We expect some folks to study our Upgrade Kits, learn from what we’ve done, and take off into new territory from there. No one is offended by that.
But our initial concept was to take an inexpensive stock amplifier, one that cost no more than $100 or so, and modify it into a professional- or recording-quality amp for very few bucks. The Valve Jr. was the amp that gave us the inspiration for this project. Epiphone broke the mold with their little Valve Jr. amp. Out of the box it’s a remarkable value. So, although it was a bit of a challenge I thought it was interesting because we were not stepping on anyone’s toes — we were just taking something that already existed and designing an Upgrade Kit around it. A simple proof of concept that made the case of transformers and guitar tone. It just seemed like a cool thing to do. The project was validated when pro players began demo’ing our prototype amps — they couldn’t believe how amazingly great such a tiny amp could sound, it freaked them out, and they all wanted one of their own!
Our intention was to give the kid who was practicing guitar in his bedroom, whose parents are on a limited budget, REAL guitar tone. In a typical scenario, the parents buy a cheap little amp and guitar combo because they want to see if their kid will stick with it. But the kid doesn’t understand that the sound of the amp is fatiguing. He doesn’t understand why the amp doesn’t sound good. And he doesn’t realize that the amp is fighting him, tiring him out. I know that happened to me and so many of my friends when we were kids. Struggling with hard-to-play guitars and poor-sounding amps is probably the single-most reason so many budding young (and old) guitarists give up the pursuit of their dream. But some are rescued. One day they visit a guy, or hear someone play, who has the amp with the tone and with just the sweep a few chords they experience the “My gawd!!! I want to sound like this!” phenomenon.
That is what we’re trying to offer with these Upgrade Kits — where the tone is accessible to just about anyone. So they could have an amp that wasn’t dull or desensitized. An amp that allows them to make that real connection to the tone. Tone is not just about noise and volume, it is rather complex, and undeniably emotional.
At the LA Amp Show we had our Upgraded Fender Champion “600” running into a full Marshall stack. Here we had this little amp powering eight 12″ speakers and it sounded great. People kept asking to see the back of the amp thinking that we had somehow rigged up something, but it was just the little Champ “600” with our Upgrade Kit.
When you have a nice open tone it is not about counting watts because the window is so big and wide and the soundstage is so deep that it gives you the impression of more power. We are not putting out more power with the Upgraded “600” — but it sure sounds like it! It’s about opening up that tone window and giving you more.
It’s kind of like taking a radio whose volume is set to half way and having it placed about 20 feet away from you then bring it right next to your ear — the volume has not changed but you hear a lot more of its content.
One of the things we do when modifying a circuit is to lower the noise floor, which a lot of people overlook. Many amps, like the Valve Jr., have a nasty hum in standby. We had one that would just start to howl if you left it alone for a while! So whatever high noise floor it had would eventually feedback on itself and cause that noise.
Our focus is on inspiring people. We are trying to show people that they really can get great tone today, that there is no age that has come and gone. There is still a lot of fun things left to do with your amplifier when you are on the search for great tone.
Hearing how much these Kits improve upon the tone of the amplifiers, and how well thought-out they are, will a Mercury amplifier that is designed and built by you ever make an appearance?
No. We are a supplier of key components to the boutique industry and to several of the large amplifier companies, and that is a comfortable spot to be in.
There is no shortage of amplifier companies out there and it really is a conflict of interest if we were to start selling amps and transformers. I would rather stay out of it.
The whole point of the Upgrade Kits was an area where I didn’t see any conflict with the people who were in the amplifier business. In the end the Kits really represent a transformer demonstration. If you were to just show someone a picture of a transformer or even had one in your hand and tried to explain how much better their tone would be, no one would care — it’s a yawner. But when you build one of these inexpensive Upgrade Kits and you actually hear the difference that the transformers make, it really drives home our point that transformers are important, that they are the building blocks of guitar amp tone.
And in the end we do this because we love it, we really love what we do. We get to create all of these products that help people find their tone, and who wouldn’t what to do that?
In late 2009 I had the opportunity to talk with Sergio Hamernik about the history of the Mercury Magnetics, how he became involved in making transformers for guitar amplifiers, and the difference a high quality transformer can make on your tone.
How did Mercury get its start?
The company’s roots date back to the early ’50s. Mercury was started by an old General Electrics transformer engineer who was working there pre-World War II. He then went on to do a bunch of design work for the war effort. And in the early ’50s, hung a shingle and became self-employed.
The name “Mercury” came out of his passion for Mercury cars, he always drove a Mercury since the late ’40s — he loved those cars — and eventually moved from the East Coast to the West Coast where he found that there was a lot of military and aerospace work. A booming economy in the early ’50s gave him a lot of business.
I met him in the 1970s when I was an engineering student and an audio enthusiast. Back then the electronics world was well into its solid-state “evolution,” and interest in tube gear was quickly disappearing. Not for me, however. I found myself in demand as a guy who knew about those “old things”; not only the math, formulas and specifications but I also had the “ears.” I could fix and keep the old gear running. So, I worked as a hired gun for a bunch of studio heads and pro musicians.
Typically when an amp’s output transformer blew. No one seemed to know any better so it was just swapped by whatever “factory” replacement or an off-the-shelf “equivalent” catalog transformer was handy. The invariable result was that the amp’s characteristic sound was gone. And no matter what resistors, caps or tubes were used, it could not be rescued or returned to its original sound. It was the transformers, it turned out, that were the key. The problem was coming up with a way to remedy the blown transformer replacement or repair that wouldn’t alter its tone.
To further complicate things, most transformer people I dealt with just didn’t want to bother with the music industry. For the most part the established electronics industry considered the needs and opinions of the audio and MI (Music Industry) communities as subjective, run by kooks, and occupied by people who didn’t know what they are doing. Audio and MI had always been considered the illegitimate stepchildren to the rest of the industry.
Out of pure necessity I had to got involved with transformer design and manufacture. As a customer of Mercury, they had built many custom transformers to my specifications — although we had many heated, on-going debates on the subject because the company owner hated audio! He never did understand what made guitar amp transformers tick, or how musicians thought and reacted to them.
That aside, he pestered me for almost a decade to take over the company because he felt I was the only one qualified. Eventually I did, and that was when Mercury got serious about the guitar amp connection. Sometimes you end up becoming an expert at something when no one else wants to do the job.
By the time I took the helm we were developing a really good and workable understanding of the relationship of transformer design to decent tone and how amps should behave. And around 1980 we began the long and arduous task of collecting and cataloging transformer specifications for every vintage amp, from all over the world. The deeper we dug, the more apparent it became that there were all kinds of factors that no one had previously suspected that affected guitar tone. And likewise, no one seemed to be paying attention to such things.
In turn, we invented proprietary technologies to aid this work. Even after three decades, we’re still innovating and discovering new things. From that fundamental research came our now famous ToneClone series, and later the Axiom line, which is probably the most significant advancement in toneful guitar amptransformer designs since the ’50s. Both product lines, we’re proud to say, have distinctly different niches in the annals of guitar amp tone.
We’ve not only cured the old transformer tone issues, but made it possible for musicians to upgrade their existing amps. And we’ve also made it possible for amp builders to reproduce amps of the same or better grade than even the most outstanding vintage amps of the past.
When did you become involved with making transformers for guitar amplifiers?
Back in the ’70s I worked for people on a one-to-one basis, usually under confidential arrangements, with certain rock stars that just didn’t want to be bothered by their names being flaunted around. What they want was their amps running right for recording, projects, touring, etc.
The problem was that when technicians would fix the amps they’d often loose their tone. It turned out that the culprit was the replaced output transformers. A changed output transformer would completely alter the character of the amplifier. So as I was the guy doing most of the work to resolve this issue, this expertise was brought to Mercury where we began a special division to cater to the guitar heroes.
Word got around rather quickly that Mercury was able to repair, rewind, and restore the original transformers and it just grew from there. The whole “Tone Clone” thing came from artists who had these amazing irreplaceable amps, amps that often made recording history. They didn’t want to take these amps on tour. So we came up with the innovative idea of cloning their original transformers that they’d fallen in love with. With the clones we could now easily make, for the first time ever, several identical amps for them. Or they would assign their techs to drop-in the cloned transformers so they would have, for example, six amps that would all sound the same as that first perfect amp.
These artists could now go on tour and not worry about breakdowns or theft, and keep their prized-originals back at home.
I worked with Ken Fisher, the whole Trainwreck thing, and a lot of the early boutique guys — and still do with Alexander Dumble. They preferred to keep things confidential and not let too many people know who their sources were because there were so few transformer designers that catered to the guitar amp market.
There was also a slow-but-steady dumbing-down occurring in audio and all that had been the post World War II momentum. Many of the ex-military components we’d been using were high tolerance parts, with mil-spec formulations of iron and copper and so on, that had been used to win the war effort. During the ’50s and ’60s we enjoyed the benefits of those high quality components at surplus prices. But by the late ’70s, and definitely in the ’80s, steel manufacturers started to change recipes to make the iron and other materials much more affordable.
You can hear the differences between a late ’60s Marshall, a late ’80s Marshall, and a Marshall today. A good listen will really help you to understand what changes took place. Unfortunately they made so many of those changes more out of economic considerations than anything else. The amps were loud but they seemed to be losing sight of the fact that their tone was disappearing — the “recipes” had been changed.
In addition to many other factors, the iron that Mercury uses is custom-formulated specifically for us. We buy enough of it to be able to dictate the exact recipe from the foundries. And all of our iron is literally from American ore processed right here in the USA. 100% American madeto the original specs. Are there drawbacks? Well, some of the iron rusts more easily, but that’s actually a good thing because rust is a natural insulator. But the opposite is also true. When you see a modern transformer with a silvery or a shiny core just know that they aren’t worth a damn when it comes to tone.
Can you tell us more about guitar amp transformer history?
Here’s an amusing anecdote that may help explain our case for guitar amp transformers: There’s a great deal of documentation, from back in the mid-’50s, where engineers, and other technical people, were writing really scathing reports on how awful the transformers were in the audio industry. Those darn transformers! When tubes were plugged into them there was a tendency to distort! And they couldn’t have any of that! Likewise with harmonic distortion — especially even-order harmonic distortion.
Many amp builders, techs and players, today, don’t understand that tubes were originally designed to run dead clean, linear, and be efficient voltage amplifiers. That the tone we’ve all come to know and love is caused by the transformers literally “irritating” the tubes into distortion.
Which is, of course, the whole point of what we are looking for in guitar amps. Back in the ’50s, they were fighting to get rid of those nasty distortion tonal characteristics. Now we embrace them. But that was audio – guitar amps were still in they’re infancy and yet to be realized. It took a generation or two of innovative musicians to take those “undesirable” tonal characteristics and create music; to work with distortion and make it into something musical.
Ironically, it was that no-distortion engineering mindset that ushered in solid-state, and why it was so openly embraced in the ’60s. It was solid-state electronics that eliminated the output transformer.
In the late ’60s, Vox went to Thomas Organ to have solid-state amps built. They were very proud of this state-of-the-art amplifier. Curiously, I met a few of the musicians from the late ’60s that were sponsored by, and using, those amps. The tone was so awful and unbearable that they used the enclosures but hid their old tube gear inside! As you may already be aware, the vacuum tube industry is alive and well, and we’re still waiting for the solid-state industry to catch up.
Part of the confusion is that musicians assume it’s the tubes that give them their tone. There’s a lot of synergy going on in an amp, and the tubes certainly contribute, but let me illustrate this another way. Did you know that there is what we call “output transformer-less” amplifiers in the HiFi world?
These amps basically parallel a bunch of power tubes together until they get down to 16, 8, or 4 ohms. There is no output transformer, so you literally connect the speaker directly to the tubes. If you ever get the opportunity to do an audio demo with this style of amp, you will find that while it works, it sounds nearly solid-state. The output transformer is what provokes a tube into giving the characteristics that we find desirable as far as tone. Audio engineers didn’t want the tubes to distort, as tubes are basically nothing more than very clean voltage amplifiers. But when you have a reactive element like a transformer, you irritate the tubes into harmonic distortion.
Therefore, the difference between a good and mediocre transformer is based on how it works and syncs with these tubes to produce the kind of tone or distortion we are looking for. It is not as easy as winding some wire around a steel core, if it was then we would not be having this conversation.
How does a Mercurytransformer made today compare to the transformers made in the golden age of amps (the ’50s and early ’60s)?
One of the biggest mistakes existing in today’s amplifier community, especially amongst hobbyists and do-it-yourselfers, is to blindly copy every aspect of a vintage amplifier hoping to get a piece of that golden tone. At best, this method still produces very random results. One of the key reasons for this is the often-overlooked missing transformer formula. A builder will fuss around with the tiniest of other details but completely miss how the transformers fit into the equation. In short, get the transformers right, then the rest is much easier. Here’s another look at theses deceptively simple devices:
For vintage-style transformers, Mercury starts by duplicating the transformer design, build errors and all. We use the best grade components like they did in the ’50s and ’60s. We wind every layer and every turn as if it were a circuit in itself. In fact, the diagram on the left shows an output transformer circuit equivalent. Most people would think it is an audio circuit. These things are fairly complex, and all the numbers have to be right in order to get the tone we want as musicians.
We really do follow the recipe to a point. Although we don’t repeat any of the mistakes or inconsistencies that were prevalent, but didn’t affect tone. For example, if you were into Fender tweeds or late-’60s Marshalls. To do this we would literally put the word out to rent or borrow dozens of amplifiers to find the one or two that had thesound, and dismiss the rest. There were typically many inconsistencies as well as “happy accidents” in the best-sounding examples we’ve auditioned. A lot of this has to do with the sloppy tolerances of the original transformers.
For our transformers we extract the best parts and virtues of the original best-of-breed transformers and remove all of the obstacles to tone. Perhaps just as important is that we adopted a “cost is no object” approach, making our transformers equal or better than the originals — and then add consistency. We now have this so finely tuned that if you bought a transformer from us five years ago, and then the same one today, it would sound exactly the same. You don’t want good batches and bad batches, which is precisely what made the original production runs vary so much.
Another issue is the so-called controversy between paper tubes and nylon bobbins. In the vintage years they used both. Some people think that somehow, some magical quality comes from using a paper tube winding form over a nylon bobbin. Tonally it made no difference at all. Paper tubes were widely out of tolerance most of the time because of how they were made. They would wind multiple coils on long sticks then use a saw or blade to cut off the various coils. In order for these long tubes or coils to come off of their winding forms they had to be conical. So this invariably meant that the first coil would be larger in diameter and the last coils smaller. As you can see, it’s easy to see why each of these inconsistently-made bobbins had a greater difference than the material they were made from. And there are other issues that occur over time, like paper has a tendency to disintegrate, collect moisture, etc.
When we switched to using nylon bobbins the tolerances were within 3,000’s of an inch of each other, as opposed to the wildly varying amounts found in paper tubes. If you were ever to take apart a really old transformer (pre-’70s) sometimes you’ll find wood wedges that are jammed between the paper tube and the core because that piece of paper was too wide and too sloppy to fit into the core correctly! They would force a wedge in there so the darn things wouldn’t rattle!
Which method, paper or nylon, made for the best tone? It’s the luck of the draw. We’re fortunate in that we have all these stars as clients who have these amazing-sounding amps. They went through the hassle of culling and choosing and picking the special amps that inspired them. The amps they recorded with. When we analyzed their transformers we sometimes found happy accidents or other little anomalies that would set a transformer apart from already sloppy tolerances of the standard production run.
There are little subtleties and changes from one transformer to another that make a heck of a difference tonally. So when you look online at our list of ToneClones, just know that they are from the hand-picked, best-of-the-best amps of their model and era. We continue this “weeding” process every day — and there’s apparently no end in sight. And that’s why, with some amps, we have several versions — each with its own tonal qualities — and others only a single set to choose from.
We use this process to establish new benchmarks. And you never know, tomorrow a new variant may arrive that totally blows away what we already thought was as good as it could ever get.
It is interesting that you take that approach to upgrading — the never-ending search for better-sounding benchmarks.
There is no real money or glamour in what we do, it is really all born of a passion for music. I come from a musical family, my Mom taught me as a little kid that music was a form of “food.” And that hasn’t changed. Everyone who works at Mercury is just in love with playing and listening to music, and we all believe that there is always some room for improvement or a way to raise the bar somehow.
Back in the ’70s and ’80s there wasn’t really a need for a company that designed and sold transformers to the public, so I stayed away from the general public for as long as I could and really only worked with professionals.
But at some point I realized that it was the average player who was getting ripped-off. Things were getting dumbed-down, the tone is slowly and steadily being vacuumed out of the amps. They were becoming duller-sounding, less interesting and more noisy. So, we decided to formally launch this product line so the average guy could have access to our technology. It takes an extreme amount of labor and effort it takes to build them to this standard. You know, even if someone wanted to buy 1000 transformers we would have to no-bid them because we really don’t have any way of doing things quickly.
Automation isn’t a practical solution. Everything we do is wound by hand, one at a time; it is the only way it can be done. Say you have 100 turns and 10 layers, well that would mean 10 turns per layer — that is how a machine would think of it. But what if a rock legend’s best transformer was 9 turns on one layer, 11 turns on the next, 7 on the next, 3 after that and so on, but the sum total ended up being 100 turns. Sometimes one layer can have a different winding style than the other; sometimes it is non-symmetrical meaning, if it is a push-pull, that one side of the primary doesn’t have the same turns as the other side. If that was the recipe that created the magic, we’d have to duplicate it. It’s just not practical to build machines to do that, so we end up having to do it by hand. It’s the proud old-school craftsmanship way of doing things. Something I think we could see a lot more these days.
We have a reputation for nailing tone. Our Fender transformers don’t sound like Marshalls, they sound like Fenders — and vice versa. In fact, we’ve become the industry’s new standard. If you were going to design or create a tube-based amp, it’s clear that we’re the folks to talk to.
Can you explain how a Mercurytransformer can improve an amplifier’s tone and how they outperform the stock transformers found in most amplifiers?
In designing toneful transformers specifically for guitars (and that’s all we’re talking about here, not necessarily transformers for HiFi or any other purpose), the trick is in the magnetic field and how it behaves. The nature and the speed with which the iron reacts to the changing of an alternating current, in an alternating magnetic field, is what makes tone happen.
If you have “slow” iron, you’ll have a dull, non-sparkly sound with no bell tones — no matter what you do with the amp it will always be kind of noisy and fuzzy.
Where others have tried and failed they’ve blindly followed generic transformer formulas without understanding that guitar amps are different animals. They’ve somehow missed that point despite all the evidence to the contrary. The fact is that transformers for guitar amps do not necessarily follow textbook rules.
Indeed, it should probably be noted that we’ve developed a whole new technology around transformer design specifically, and only for the guitar industry. And that these designs are essentially irrelevant to any other use. But Mercury is also in a highly unusual position. Our decades of transformer “vivisection” have revealed all manner of unconventional tips ‘n tricks to us. And we’re now the keepers of this new, but proprietary, technology.
I seriously doubt that we could have done it without the, let’s call it “archeological benefits,” of our observations. Decades of studying the good, the bad and the ugly of guitar amp transformers have revealed a great deal.
Nothing that I have found in the reissue market, transformer-wise, even resembles anything that was made during the “the golden age of tone.” They are unrelated. The inductance, magnetic fields — all of that is just completely different and far removed from the original designs and recipes. So there is no way that a reissue amp is ever going to sound vintage unless they bother putting in the right ingredients.
With our Upgrade Kits, for example we’re trying to show people that we can move forward into new sonic territory from where vintage designs and tone left off. And our Axiom series transformers are the definitive showcase for this technology. Their tone is just amazing.
To push the point even further, we don’t include any “voodoo” parts in our Upgrade Kits. With the exception of the transformers, the Kits use only common, everyday, and off-the-shelf components. And most of our Kits also include a Mini-Choke. When the circuitry is correctly designed a Mini-Choke will make a huge improvement in an amp’s tone because, in terms of its power supply, it changes the way the amp works.
A good guitar amp is only as good as its power supply. If you have a dynamic and moving power supply that reacts to the demands of the audio end you’ll get get great note separation and good bass dynamics. You start to hear chimes and other phenomenon, and even the harmonics between the strings like a “5th note.” What the heck is the “5th note”? In barbershop quartets, if they get their harmonies right, they hear the “5th note” which is basically a harmonic of all four singers. We are doing that with our guitars thanks to distorted amplifiers.
Where did the idea for offering an Upgrade Kit for amplifiers like the Champ “600” and Valve Jr. come from and who designed the Upgrade?
I designed all of the magnetics (the transformersandMini-Choke) and the general concept behind the Upgrade in league with Allen Cyr from the Amp Exchange. He is one of the most competent, finest amp designers I know of; there are only about five in the world that are true masters of the art — those who really know the math, how to read tone, how to listen to the subtleties of clean and overdriven sounds and tones, design circuits, and understand tube behaviors. As a bonus to those who appreciate this kind of thing, we always try to throw in some interesting tweaks and tricks that are unorthodox.
The idea is to spark some interest and perhaps get more people involved in tube-based amp tone and evolution. We expect some folks to study our Upgrade Kits, learn from what we’ve done, and take off into new territory from there. No one is offended by that.
But our initial concept was to take an inexpensive stock amplifier, one that cost no more than $100 or so, and modify it into a professional- or recording-quality amp for very few bucks. The Valve Jr. was the amp that gave us the inspiration for this project. Epiphone broke the mold with their little Valve Jr. amp. Out of the box it’s a remarkable value. So, although it was a bit of a challenge I thought it was interesting because we were not stepping on anyone’s toes — we were just taking something that already existed and designing an Upgrade Kit around it. A simple proof of concept that made the case of transformers and guitar tone. It just seemed like a cool thing to do. The project was validated when pro players began demo’ing our prototype amps — they couldn’t believe how amazingly great such a tiny amp could sound, it freaked them out, and they all wanted one of their own!
Our intention was to give the kid who was practicing guitar in his bedroom, whose parents are on a limited budget, REAL guitar tone. In a typical scenario, the parents buy a cheap little amp and guitar combo because they want to see if their kid will stick with it. But the kid doesn’t understand that the sound of the amp is fatiguing. He doesn’t understand why the amp doesn’t sound good. And he doesn’t realize that the amp is fighting him, tiring him out. I know that happened to me and so many of my friends when we were kids. Struggling with hard-to-play guitars and poor-sounding amps is probably the single-most reason so many budding young (and old) guitarists give up the pursuit of their dream. But some are rescued. One day they visit a guy, or hear someone play, who has the amp with the tone and with just the sweep a few chords they experience the “My gawd!!! I want to sound like this!” phenomenon.
That is what we’re trying to offer with these Upgrade Kits — where thetone is accessible to just about anyone. So they could have an amp that wasn’t dull or desensitized. An amp that allows them to make that real connection to the tone. Tone is not just about noise and volume, it is rather complex, and undeniably emotional.
At the LA Amp Show we had our Upgraded Fender Champion “600” running into a full Marshall stack. Here we had this little amp powering eight 12″ speakers and it sounded great. People kept asking to see the back of the amp thinking that we had somehow rigged up something, but it was just the little Champ “600” with our Upgrade Kit.
When you have a nice open tone it is not about counting watts because the window is so big and wide and the soundstage is so deep that it gives you the impression of more power. We are not putting out more power with the Upgraded “600” — but it sure sounds like it! It’s about opening up that tone window and giving you more.
It’s kind of like taking a radio whose volume is set to half way and having it placed about 20 feet away from you then bring it right next to your ear — the volume has not changed but you hear a lot more of its content.
One of the things we do when modifying a circuit is to lower the noise floor, which a lot of people overlook. Many amps, like the Valve Jr., have a nasty hum in standby. We had one that would just start to howl if you left it alone for a while! So whatever high noise floor it had would eventually feedback on itself and cause that noise.
Our focus is on inspiring people. We are trying to show people that they really can get great tone today, that there is no age that has come and gone. There is still a lot of fun things left to do with your amplifier when you are on the search for great tone.
Hearing how much these Kits improve upon the tone of the amplifiers, and how well thought-out they are, will a Mercury amplifier that is designed and built by you ever make an appearance?
No. We are a supplier of key components to the boutique industry and to several of the large amplifier companies, and that is a comfortable spot to be in.
There is no shortage of amplifier companies out there and it really is a conflict of interest if we were to start selling amps and transformers. I would rather stay out of it.
The whole point of the Upgrade Kits was an area where I didn’t see any conflict with the people who were in the amplifier business. In the end the Kits really represent a transformer demonstration. If you were to just show someone a picture of a transformer or even had one in your hand and tried to explain how much better their tone would be, no one would care — it’s a yawner. But when you build one of these inexpensive Upgrade Kits and you actually hear the difference that the transformers make, it really drives home our point that transformers are important, that they are the building blocks of guitar amp tone.
And in the end we do this because we love it, we really love what we do. We get to create all of these products that help people find their tone, and who wouldn’t what to do that?
Source: https://mercurymagnetics.com/pages/news/GuitarFixation/SHinterview/index.htm
We always maintain a steady flow of gear arriving for review, but sometimes we also employ a fascinating if time-consuming research strategy that involves logging onto eBay, picking a broad category such as “guitar amplifiers,” and settling in for as long as it takes to patiently scroll through every page of listings. Yeah, that’s often 50 pages or more, but since we can’t possibly think of all the items that might interest us and search for them by name, it’s far more revealing and productive to just hunker down and scroll. Rarely do we fail to find something intriguing that would have otherwise been missed, and such was the case on a morning in August when we stumbled on a listing for a 1959 tweed Deluxe. Were we looking for a tweed Deluxe? Nope. Wouldn’t have crossed our mind at the time…. We had already reviewed 5E3 reproductions from Fender, Clark and Louis Electric within the past 3 years, and we have frequently referenced our 1958 Tremolux as being our desert island #1. Isn’t a Tremolux just a tweed Deluxe with tremolo in a bigger box? No… not even close. That would be like saying you wanted to date a blonde – any blonde. For the record, our fixed bias Tremolux possesses a cleaner tone with a bigger, booming voice created by the taller Pro cabinet. The Two Fifty Nine is a completely different animal….
Sporting a February 1959 date code on the tube chart, the ’59 had been listed by a seller in Arkansas who turned out to be Tut Campbell, formerly a well-known guitar dealer in Atlanta. Still buying and selling gear, Campbell had described the Deluxe as being in original condition with the exception of a replace output transformer – a big old mono block Stancor dating to 1957. Given the otherwise original condition of the Deluxe, which included the Jensen P12R, we made Campbell a “best off” below his asking price and scored the amp for $1,850 shipped. We wouldn’t say we stole the Deluxe, but it seemed a fair price of admission for the opportunity to experience and explore still another rare classic and supremely worthy piece of Fender history on your behalf.
The Deluxe arrived with the big Stancor dangling from the chassis despite Campbell’s careful packaging. Wasn’t his fault, really – in a feeble effort to avoid any additional holes being drilled in the chassis, the fellow who installed the Stancor in the ’60s had merely tightened set screws over the small tabs at the base of the heavy tranny, which was designed to be mounted upright – not hanging upside down in a guitar amplifier. Of more concern was the fact that while the amp was lighting up, there was no sound…. Well, we’ve been here before, so we made a call to God’s Country and the Columbus, Indiana domicile of Terry Dobbs – Mr. Valco to you. We had already set aside a spare output transformer (Lenco, McHenry, IL) that had been the original replacement installed in our ’58 Tremolux when we first received it, replaced with a Mercury Magneticsfor our June ’07 review article. Mr. Valco cheerfully answered his phone and as we explained the situation with the Deluxe he agreed to walk us through the installation of the new replacement – a simple process involving four lead wires being connected to the rectifier and output tube sockets, and the speaker jack. As long as you put the correct wires in the right place, a piece of cake, and we had the new tranny in within 10 minutes. Pilot lamp and all tubes glowing, still no sound…. Valco patiently guided us through a series of diagnostics with the multi-meter and the Deluxe was running on all cylinders, pumping 380 volts. Stumped, and with the hour growing late, we called it a day. Leaving the mysteriously neutered Deluxe chassis on the bench until tomorrow.
Morning came with a whining voice delivering a plaintive wake up call – “It’s got to be something stupid and simple….” Inspired by a huge steaming mug of Jamaican High Mountain meth, we sat back down at the bench, tilted the innards of the Deluxe chassis forward beneath a bright halogen desk lamp and peered in for answers. We began slowly examining the chassis in sections, looking for broken or dull solder joints, loose or broken wires, while gently pushing and prodding wires and connections with the eraser tip of a #2 pencil as we had seen Jeff Bakos do so often at his bench. After ten minutes or so we were about to give up, when we turned our attention to several places where the circuit was grounded to the chassis adjacent to the volume and tone pots, and damned if a solder joint for one of the uninsulated ground wires hadn’t separated from the chassis. No ground, no sound, and as soon as we had restored the solder joint the Two Fifty Nine arose from the dead with a mighty A major roar.
The amp was indeed remarkably well-preserved in all respects, with the typical amber patina of old tweed. The burnished chrome control panel remained bright and clean with no corrosion, the original handle remained intact, and a couple of small ciggie burns on the edge of the cabinet added a stamp of historic legitimacy to the Deluxe’s pedigree. The top half of the Jensen’s frame was coated in a fine film of red clay dust from the Delta, and while the cone was in remarkably good shape with no tears, an audible voice coil rub called for a recone. We would send the speaker to Tom Colvin’s Speaker Workshop in Ft. Wayne, Indiana, requesting that he leave the original unbroken solder joints for the speaker wires intact if possible.
Meanwhile the first order of business was to listen to an assortment of NOS tubes from our stash, and audition no less than a half dozen speakers. Different sets of power tubes and individual preamp tubes will sound surprisingly different, so we started out with a matched pair of NOS RCA 6V6s, a GE 5Y3 rectifier, and an RCA 12AX7 and 12AY7. From there we subbed in a dozen different RCA, Amperex, Tesla and GE 12AX7s, noting varying levels of brightness, warmth and intensity among them all. For an edgier, more aggressive voice, the GEs and Amperex typically deliver the goods, while RCAs produce a slightly warmer, richer, fuller tone. We also experimented with a 12AT7 and 12AX7 in place of the lower gain 12AY7, and while those tubes ramp up gain and distortion faster and with more intensity than the 12AY7, they seemed like overkill for us. Our Deluxe possesses a tone of gain using the stock 12AY7.
Rather than repeatedly reloading the Deluxe with different speakers, we used a Bob Burt 1×12 cabinet built from 100-year-old pine for our speaker tests. The original Jensen had never been pulled from our amp, but multiple speaker replacements in an old Fender inevitably cause the speaker mounting screws to loosen in the baffleboard, making speaker swaps unnecessarily clumsy and complicated. When we do run into loose mounting screws, we simply run a few small drops of Super Glue around the base of the screw and surrounding wood. Allow to dry and your screws will stay put provided that you don’t torque the nuts on the mounting screws like an idiot with a socket wrench. Don’t be that guy,
We tested a range of speakers that included a Celestion G12H 70thAnniversary, Colvin-reconed ’64 Jensen C12N, Eminence Wizard, Private Jack, Alnico Red Fang, Teas Heat, Screaming Eagle, Red, White & Blues, and Warehouse Green Beret, Veteran 30, Alnico Blackhawk and Alnico Black & Blue. The Alnico speakers generally produce a tighter, smoother, slightly more compressed tone, with a variable emphasis on upper mid-range and treble frequencies, while the speakers with ceramic magnets possess a wider, more open sound. Higher power ratings of 75W-100W offered by the Red, White & Blues, Screaming Eagle and Warehouse Blackhawk typically translate into more graceful handling of bass frequencies, and in a 20 watt Deluxe, zero speaker distortion, for a clean, powerful voice.
Let’s cut to the chase with speaker evaluations, shall we? It has become clear to us that even after reviewing a dozen speakers in as much detail as mere words allow in a single article, many of you remain uncertain about which speaker to choose. No kidding. We would absolutely love to hand you a single magic bullet when it comes to speaker swaps, but here’s the dirty little secret about choosing speakers…. The overall character of the amp you will be installing your new speaker in is critical, and to some extent, the type of guitars and pickups you play most often are important, too. Tailoring your sound with the unique gear you play is not a one-size fits-all proposition – you have to invest some thought into the process. Are you going for a classic “scooped” American Fendery tone, or something more British, with a bit of an aggressive edge and upper midrange voice? Are you playing guitars with single coil pickups or humbuckers? Is there a specific, signature tone you are searching for, or are you playing a wide variety of musical styles that requires a broader range of tones? Do you like the more open sound of speakers with ceramic magnets, or the smoother compression of Alnico? What are you not hearing from your amp and the speaker that’s in it now? Do you want a brighter tone, darker, better bass response, or fuller, more prominent mids? Do you want to really drive the speaker and hear it contributing to the overdriven sound of your amp, or do you want a big, clean tone with no speaker distortion in the mix? The truth is, if you don’t know what you want, you are far less likely to get it. On the other hand, nothing is accomplished with paralysis by analysis. To be perfectly honest, there are lots of speakers made by Celestion, Eminence, Warehouse and, if you can wait long enough for them to break in, Jensen, that we could and would be perfectly happy with, but we would also choose them carefully, taking into account all the factors mentioned above. After a couple of days spent swapping speakers, we ultimately concluded that we preferred the ’64 C12N for a classic tweed Deluxe tone, and a broken-in Celestion G12H 70th Anniversary for the most mind-altering 18 watt Marshall tone we have ever heard. Seriously. More on that in a minute….
Having split more than a few hairs with our speaker swaps, it was time to start picking nits off of gnats with some output transformer evaluations. We first contacted Dave Allen of Allen Amplification, who also stocks Heyboer transformers built to his specs. We found a variety of appropriate output transformers on Allen’s site that offered subtle variations on a stock original Deluxe OT, and we asked Dave to describe the TO26 model we wished to try in the Deluxe:
“The TO26 was intended as a hot rodding upgrade to a stock Deluxe Reverb OT. While maintaining the stock 3-1/8” mounting centers, its fat stack of hotter core steel and multi-tap secondary make it a good choice for builders wanting to maximize the performance of a pair of 6V6s and who may also want to push the envelope with 6L6/5881s while still being able to clear the speaker in a stock cabinet. There are physical limitations in small amps, so its short low profile is welcome. The orientation of the laminations is also good for low hum pick up from the power transformer. I found that an OT mounted the tall way (like my TO30D) picks up considerably more hum simply due to its orientation to the power transformer, so, shoe-horning a ‘tallish’ OT into your amp may cause it to pick up hum from the power transformer – not much of an upgrade. “The TO26’s 7K to 8 or 16 ohm rating makes it ideal for a pair of 6V6s as well as 3,500 ohm to 4 or 8 rating for 6L6/5881s. Notice you always have an 8 ohm option with both types of power tubes. An impedance switch could be wired (I use a blackface grounding switch) as a power tube type selector for an 8 ohm speaker to go between 6V6s and 6L6s. The TO26 will typically give slightly more output with 6V6s due to its more efficient low-loss core steel and will keep the bass clean longer for more perceived clean headroom. As it takes the most watts to reproduce the bass, you notice distortion there first, and since Fender-type amps are so bass heavy, you can quickly hit the wall with headroom, so a noticeable increase in clean bass response certainly feels like a more powerful amp with the TO26. It is kind of like you installed a new speaker with a larger ceramic magnet that is more efficient than the old speaker. The amp is a little louder and the bass a little tighter or cleaner.
“There seem to be a lot of 6L6-based 5E3 amps out there now to get a little clean headroom from a circuit normally not known for much of that. The TO26 is a good choice for that type of amp as it will fit typical available chassis and cabinets. It has extra long 12” topcoat leads ready to strip and solder. I would reckon it would handle up to about 30 watts before starting to saturate and compress – plenty of cathode-biased 6L6s. I find that the Heyboer paper stick-wound and interleaved output transformers with premium core steel and heavy core stacks have typically better clarity or definition than ‘stock’ OTs. Call it fidelity or whatever you want – just clearer distorted and complex tones and better separation of notes in chords, etc. I use the TO26 in the Allen Sweet Spot, Accomplice Jr. and Hot Fudge with Nuts amps with excellent results. All of these amps can use either 6V6 or 6L6 power tubes. You know how a 5F6-A or Super Reverb has that huge 4 bolt OT for a pair of 6L6s to get the maximum clean bottom end? That is sort of what the TO26’s OT is to a pair of 6V6s. It just doesn’t even come close to saturating.
When we informed Dave that we planned to run the Deluxe with 6L6/5881 power tubes as well as 6V6s, he recommended that we try the TO26 since it had been specifically designed for such applications. He also sent a smaller TO20 transformer, described as being designed with a wider 1-1/4′′ lamination “fat stack” that provides 60% additional core mass than typical ¾′′ stack units for improved performance. The TO20 is a direct replacement for Blues Jr. and Princeton Reverb amps, and also suitable for dual EL-84 amps with an 8 ohm load.
Mr. Valco also sent us a replacement 5E3 output transformer he had bought on sale from Clark Amplification a few years ago made for Mike Clark by Magnetics Components in Schiller Park, IL – a company that has been producing transformers since 1943, having been the primary supplier for Valco and various Gibson amps in the ’50s and ’60s. A call to the company revealed that ToneQuest ReportV12. N1. Nov. 20104the transformer Valco sent was essentially their replacement for a Deluxe Reverb, model #40-18002 without bell ends per Clark’s request. We also learned that the company offers a complete range of Classic Tone vintage power and output transformers, including a reverse-engineered clone of a ’55 Triad 5E3 output tranny, model #18022.
We also contacted Paul Patronete at Mercury and requested a ToneClone “brown Deluxe” output transformer, since Larry Cragg had provided them with specific measurements from original OT in Neil’s ’61 tweed Deluxe, confirming that it was indeed a ’61–’62 brown Deluxe tranny. With a total of 6 output transformers to listen to, we took the Deluxe to Jeff Bakos, who set up a rig on his bench that enabled us to clip in each transformer and very quickly switch back and forth between them as we played a guitar through the amp. Are we having fun yet? Here’s what we heard:
Lenco – An excellent authentic “vintage” vibe for those that prefer the classic, if somewhat murkier sound of a tweed amp being pushed, lots of sag in the low end and a jangly pop in the top. And “old,” rather “lo-fi” sound indicative of the ’50s era amps.
Magnetics Components Clark Deluxe 18002 – Similar to the Lenco, but stronger and more robust, with a prominent growling character and voice. Thick, wooly and willin’ with better treble presence and clear string definition then the Lenco, yet an entirely “vintage” character. This tranny is comparable to those found in Deluxe amps from the brown era through silverface. Excellent power, punchy and fat with exceptional clarity and tone.
Magnetic Components 5E3 Clone – Percussive and dynamic with a faster attack response than the Clark/Deluxe Reverb version, this transformer was reverse-engineered from an original ’55 Deluxe OT. IT imparts an intense, throaty tweed character with enhanced mid and treble presence, remarkable clarity, and an authentic vintage ’50s vocal tone with softer bass response and slightly less volume and power than the Deluxe 18002.
Allen/Heyboer TO20 – An interesting variation with a much more modern, percussive dynamic character. The sound was not as heavy and imposing in the vintage style, and with this transformer the Deluxe reminded us of the more refined sound of a Fender Princeton, with excellent dynamic punch for slide and Allen/Heyboer TO26 – As advertised, the low end held up loud and proud with very little sag and an audibly higher threshold of clean headroom, although beyond 6 on the volume control the Deluxe was still holding nothing back. Overall, this transformer imparts a cleaner, high fidelity tone with more clarity and stout bass response than a typical stock 5E3 transformer. An excellent choice for enhanced low-end and maximum volume.
Mercury Magnetics brown Deluxe – Immediately recognizable, the Mercury displayed a trademark sound that is smooth, exceptionally musical, warm and balanced. Sounding more “high fidelity” than the Lemco or Magnetic Components transformers, but still seductively unruly enough to get yer ya-ya’s out. Sweet, rich, detailed and sticky.
Now, you may be wondering why we would bother to audition so many output transformers…. How much difference can it make? Well, forty-odd years ago when someone rigged that old Stancor tranny in the Deluxe, the only choice available to most repair shops was whatever was on hand in the scrap pile. Today we can shape the tone and dynamic response of an amp with a variety of “vintage” or more modern, custom transformers that allow us to recapture the original sound and feel of the amp, or improve upon the original design. Why did Cesar Diaz install output transformers for a Twin Reverb in Stevie’s Super Reverb amps, and Bassman transformers in his Vibroverbs? Because the first thing that chokes and overwhelms a smaller output transformer are the bass frequencies, and Cesar wanted Stevie’s amps to produce a rock-solid, thundering low end that could handle his massive wound strings. The tone we’re celebrating with our ’59 Deluxe is quite the opposite…. The raucous sound of the amp teetering on the edge is the key to it’s exploding tone, but if you wanted to go in the opposite direction with more headroom and a tighter low end, transformers like the TO26 have been specifically designed for that purpose. We once replaced the output transformer in our Pro reverb with a bigger MercuryToneClone Bassman, and the Pro grained a tone of clean headroom and unyielding bottom. Wanna make it even harder still? Use a plug-in diode rectifier in place of the 5AR4 rectifier tube. No saggy britches now. As with so many choices we make in the Quest for tone, the final decision comes down to your mission and individual taste, and Jeff agreed that between the Heyboer TO26, both Magnetic Components trannies and the Mercury brown Deluxe, the question wasn’t which one was “best” – all four were exceptional, but different. Some players would prefer one over another for different reasons described here, but all of them represent stellar examples of just how far we’ve come since the day that old Stancor tranny was used to put the Two Fifty Nine back into service.
One last detail needed to be addressed…. Could we safely run the Deluxe with 5881s or 6L6s if we preferred that sound over 6V6s? Once again, we asked the prescient Mr. Valco for some Hoosier insight:
“The impedance mismatch in this particular amp using the 6L6s is really not a big concern, it won’t hurt the amp and will either sound good or it won’t. The 6L6s draw 1.8 amps and two 6V6s draw 0.9 amp, so using the 6L6s will add about 1 amp more current draw that the power transformer needs to supply from the 6.3 volt heater windings. On some small 6V6 amps, using 6L6s can and does cause the power transformer to run hotter because more current equates to more heat. The concern is that the power transformer in the Deluxe, not being a large one to start with, has the extra 1 amp of heater current capacity to safely use the 6L6s. One way to determine if the power transformer is really stressed out with the 6L6s is to measure the AC heater voltage on pins 2 and 7 on the power tube sockets (or on the pilot lamp) and see if the AC voltage drops significantly from the reading using 6V6s versus 6L6s. It should be a bit over 6.3 volts AC with the 6V6 anyway (since the wall voltage is higher these days than in the early ’60s) and with the 6L6s you sure don’t want to see a large drop in voltage below 6.3 volts AC. If there is a large drop it means the transformer is having trouble supplying enough current for the 6L6 heaters if given enough time with the 6L6s could damage the power transformer. If the drop is only a few 10th of a volt, and doesn’t go below 6.3 AC, then it would indicate that the transformer is supplying the demand for the heater current and should be OK. Most Fender amps used power transformers that could handle some extra current demand.
And now we arrive at the moment of truth. We’ve been steadily reeling in a parade of new and classic amps for review in these pages for 12 years now this month – Marshall, Fender, Magnatone, Hiwatt, Vox, Valco, Silvertone, Ampeg, Gibson, Gretsch, Mesa Boogie, Park, Supro, Dickerson, Traynor, Budda, Western Auto, Standel, Dumble, Cornell, Clark, Crate, Divided by 132, Reeves, Bad Cat, Gabriel, Fuchs, Koch, Star, Category 5, 65 Amps, Balls, Bakos, Callaham, Blankenship, Reinhardt, Grammatico, Siegmund, Chicago Blues Box, Roccaforte, Headstrong, Rivera, Mad Professor, Talos, Maven Peal, Reverend, BC Audio, Savage, Goodsell, Fargen, Carol-Ann, DST, Two Rock, Germino, Matchless, Louis Electric, Swart, Demeter, Juke, Aiken, Bluetron, DeArmond, Carr, Victoria, and Dr. Z, with more coming. Lots of amplifiers, multiple models from the same builders, and among the foremost classics – Fender, Marshall, Vox, Hiwatt, Gibson, Ampeg and the entire Valco catalog, we have acquired, optimized and restored dozens of amps considered to be among the most desirable vintage models ever built. In the 20 watt wheelhouse occupied by the Two Fifty Nine, it has no equal by a mile. Game over.
After a lot of back and forth testing with different sets of output tubes, we became hooked on the thundering sound produced by a pair of Philips small-bottle 6L6WGBs. Thanks to Larry Pogreba’s talent for scavenging rare tubes (in Montana, no less), we are flush with several outstanding and stout pairs of RCA 6L6s, but the brighter Philips really lit up the Deluxe with a fresh and lively attitude that mirrors the bounce of a newer amp. With the ’64 Jensen C12N loaded, the Deluxe spookily nails the tones of Neil Young’s rig on Ragged Glory – a “studio” recording cut live with the Deluxe and Old Black in a barn on Young’s ranch with Crazy Horse. With the volume backed off to 4-5 a bluesy jangle emerges anchored by solid low end, rich midrange, the sweetest treble tones imaginable, and variable levels of sustain and edgy distortion that can be controlled both by the volume on the guitar and pick attack. The Deluxe does not discriminate between single coils or humbuckers, ravaging both with equal fervor, and the responsive dynamic character of this amp simply is not of this world. Rotating the single tone control sharpens treble without dumping lows or mids, while also subtlety increasing gain, as if you were using a boost pedal. A “Y” cord plugged into the Instrument and Microphone inputs enables the two channels to be mixed with great effect. As Neil Young described, bringing the mic input volume up with the instrument volume set between 6-8 gradually deepens the tone while slowly igniting an intense explosion of thicker second order harmonics and distortion as the dynamic character of the amp softens. Pushing the Instrument volume level up into the 8-12 range brings the volume up to a perceived level that exceeds 20 watts, while provoking an angry, pissed-off cascade of astonishingly rich musical distortion as the notes swerve into controlled harmonic feedback.
Switching from the Jensen to the Celestion transforms the Deluxe into the most stunningly toneful 20 watt Marshall you could possibly imagine. To be honest, you probably can’t imagine it, because we have never heard anything like this ourselves, even after owning a couple of vintage Marshall PA20s, a rare Lead & Bass head and 1×12 cabinet, and a Balls 2×12 18 watt. We could easily live with either speaker, and the Deluxe also just kills pushing our 8 ohm 4×12 pinstripe cabinet.
For those of you who appreciate a somewhat tamer vibe, we can assure you that the Deluxe loaded with a fine pair of 6V6s is equally mind-altering. The overall sound is a wee bit smaller in girth and less imposing, yet abundantly overflowing with vivid harmonic depth, a supremely touch-sensitive response, and brilliant combination of fidelity, clarity and bloom. Compared to a black or silverface Deluxe Reverb, the ’59 presents a more musically complex soundstage, less harsh, stiff and linear, and it lacks both the sharper treble of a blackface amp, and the scooped midrange character. The tone is rounder and meatier, the treble sweeter and less dominant, with an enhanced 3-D image.
Now, if you’re the type that skeptically requires a qualifier to add a stamp of legitimacy to such an over-the-top review, here it is, Mr. Been There-Done That…. The Deluxe doesn’t and won’t spew big clean tones at stage volume. Our ’58 Tremolux produces a cleaner tone with a higher threshold of clean headroom by far at comparable volume levels, and the taller tweed cabinet encourages a stronger, cleaner resonant bass and low mid response. The Tremolux is also equipped with a Mercury ToneClone Tremolux output transformer, which creates a tone that is less wooly, raucous and indistinct.
The busted-up sound of the Tremolux above 5–6 is gloriously righteous indeed, but with more clarity and less provocative intensity than the Deluxe. Taken in context, what we’re suggesting here is that in our experience, the Deluxe has no equal as both a Fender and Marshall style 20 watt rocker (depending on speaker selection), and we’ll add “blues” to that description equipped with 6V6s and the Jensen C12N. During our 2-month test period, we also routinely used our Lee Jackson Mr. Springgy reverb, Analogman-modded Boss DD3 digital delay, and a very cool, versatile (and cheap) Flip tube tremolo pedal reviewed here. Can a modern replica of the 5E3 Deluxe deliver the same inspiring tones as the Two Fifty Nine? The closest thing we’ve heard is the Louis Electric “Buster,” but no, magical happy accidents like this Deluxe can’t be reproduced today – and that is as it should and shall always be. Quest forth…
Seen the price of a vintage Marshall Plexi lately? Your three grand won’t guarantee a virgin circuit or great tone, but if real Plexi tone is what you’re all about, you can get there for a lot less, guaranteed. When TQR Advisory board member and Sheryl Crow guitarist Peter Stroud decided to make a Plexi from his late ’70s fawn 100W head, we enlisted the capable assistance of our main toneman Don Butler and the team at Mercury Magnetics, home of
the ToneClone line of authentic vintage-style replacement transformers. Mercury has blueprinted and reproduced nearly every vintage transformer made for guitar amplifiers, and they can rewind any blown transformer to exact, original specs and sound. So settle back and enjoy the following discussion and review of Peter Stroud’s successful conversion of a common (they built 1,000s) Marshall 100W into a stellar 100W Plexi.
TQR: What is the origin and general history of this Marshall amp?
Peter: I bought this amp about 10 years ago with the matching straight-front 4×12, 100 watt cab from a dealer down in Texas. It’s a ’77 Super Lead 100 watt 4-input. I was big into collecting the f awn-colored Marshalls at the time – a poor man’s custom color. Around the same time, I had learned how to work on my own amps from the standpoint of preventive maintenance and tone tweaking, so I converted the amp over to a cascade-style master volume circuit like a late ’70s head or JCM800. Eventually, I missed having the 4-input sound and put it back to its original wiring.
Don: This amp was a standard 100 watt, non-master Marshall from the late ’70s. Some mods had been done and then undone. A few coupling caps had been changed as well as a few resistors
Strengths: Semi-loud. Typical PCB Marshall from this era. Better quality glass board than what’s used now.
Shortcomings: Ceramic caps. This amp was voiced for brighter sound, less bottom, and quicker distortion onset that original ’60s versions didn’t employ. It still had a couple of the original filter cans. The amp sounded exactly the same no matter what guitar was plugged up to it – no tonal distinction between any instrument at all! Very over-emphasized, weird G string odd harmonics (most likely old filter cap related). I have to add from a personal note that this was the worst sounding Marshall I’d ever heard or played! In a word – no tone!
TQR: Describe the specific improvements that you wanted to make to the amp, both from a technical perspective, and sound-wise. What components were changed and why?
Peter: I don’t know why – from my monkeying around with it perhaps (laughs), but this Marshall just sounded like crap. Every time I plugged in I would end up turning it off – totally uninspiring. I replaced tubes and a cap here and there but resigned to the notion that it might be the transformers. I had replaced all of the power supply caps, but not the 50/50mf in the preamp circuit. It could have been that – who knows? But in any case, I would have thrown it on eBay had it not been for the color. Instead, I decided to make it a guinea pig. I’ve been messing around inside my amps again recently and have had a real desire for that 100 watt Plexi sound and the cleaner, fuller tone they deliver. This head was far from it! Having read the ToneQuest interview with Sergio about Mercury Magneticstransformers and poking around their website, I figured the fawn 100 watt would be the perfect amp for a conversion – change out the transformers for high voltage models reminiscent of the Plexis and wire it up exactly like a ’67. I was determined to demystify the whole Plexi thing once and for all for my own comfort. After seeing how Mercury Magnetics had “cloned” the power and output trannies of an old Plexi, I felt the missing link had now appeared. Then you stepped in and it mushroomed into a topic for ToneQuest, and a very deserved one indeed. Nothing better than to see if any Marshall can become a Plexi, especially since the latest prices on eBay for Plexis are more than I care to spend. I need amps that are bulletproof and easy to replace. I spoke with Sergioand Paul at Mercury and they eventually hooked me up with Don Butler. I was thrilled to have Don take over the job knowing his ear for tone and knowledge of Plexis. There were three CD’s I used as a tone reference: bootlegs of Cream in ’67 and Jeff Beck in ’68, and the Hendrix at Monterey Pop Festival album.
Don: Peter wanted the amp to sound like a mid-to-late ’60s Plexi 100 watter. More specifically – a ’67. I replaced all the little green (or were they grey?) ceramic caps with polyester tubular caps and replaced any resistors that needed to be changed with carbon comp types. Polyester caps were used in the ’60s in all Marshalls for the main tone and coupling caps. I know for the higher value caps in the pico farad range, Marshall generally used the ones from Lemco or RS that were a flat mica-looking cap covered in a baked on ceramic or wax dipped coating. I used silver micas for those in Peter’s amp. I like the smoothness and more transparent quality of silver mica. The original polyester coupling and tone caps that Marshall used in the ’60s were from a company in the Czech Republic called Iskra. I believe Phillips imported those to the U.K. Those are the ones everyone refers to as the mustard caps. I used Mercury’s Plexi 100 output tranny, 10H choke and 100W Plexi power tranny that provides the B+ with around 525V DC after rectification. In my humble opinion, Mercury makes the best sounding, most accurate and most reliable clone transformers on the planet.
I also used the FRED rectifiers in place of the little cheap-o IN4007 diodes for the rectifier. I like the way they smooth out the harshness of the treble frequencies and take out that mid range bump that’s common with a solid state rectifier in amps. They also seem to add more note clarity, harmonics, and detail to the sound and tone of an amp. I replaced the components, transformers and the remaining filter cans. I then converted the circuit to what was used in 1967 in terms of how it was wired and component values.
Really, it’s not much. On the first valve/tube you remove the wire coming from pin #8 and shorten it and solder it to pin #3. The cathodes on that tube were shared and went to an 820 W resistor with a 250mf @ 25v cap paralleled with it to earth/ground. The second valve/tube did not have a cathode bypass cap in those days – only the resistor. There was a .68 cap I removed from that spot. I also removed the .004 cap from the volume pot on channel #1. That cap makes the amp distort quicker, and usually at just “2” on the volume pot you’re out of clean headroom and well into distortion land. That’s not what Peter wanted or what the old amps were like. I also used two 0.1/ 600V caps coming out of the phase inverter vs. the .022/600V caps that Marshall started using in around ’69 to brighten up their amps.
On the later Plexis you will find a 500rf and 33K slope resistor on Lead models and a 250rf & 56K slope resistor on Bass & PA models. Most, if not all of the schematics I’ve seen for early 100 watt Plexis used the 250pf & 56K in the tone stack. Peter’s amp had the 500rf and 33K. I replaced the 33K with the 56K for more bottom and hit a mid point between the 500rf & 250rf and used a 390rf cap for the treble control. Not too bright and not dark. With Some Lead amps, you have to turn the treble off and even then it can still be too much. I’ve found that by using a 390rf you get a happy medium point where the treble pot is still useable. All I did was put the amp into what Marshall’s circuit was in 1967 and used the same values and type of components they used, with a few improvements like the FRED rectifiers.
TQR:What type and brand of tubes were selected and why?
Don: I used the Svetlana EL-34s, as I’ve found them to sound extremely close to what the old Mullard xf3s offered in tone, as well as reliability. I’ve compared them side by side in my old 50-watter and in my ’64 VoxAC-50 and it’s really close. Preamp tubes – I used the new Ei Elite gold pin 12AX7s. To me they sound very nice and close to old Brimars and Mullards. Don’t forget that the Phillips Electronics Corp. once owned Mullard and Ei among many other subsidiaries. Ei seems to have made an excellent attempt at creating a good sounding, reliable 12AX7 that they pre-test before sending out. My favorite 12AX7-type of valve/tube for Marshall’s are the Brimars, as they offer a bit of that aggressive old tone that Marshall’s are famous for.
In part I of our Marshall JTM-45 transformation process, we installed a point-to-point board from Metropoulos Amplification (www.metroamp.com) and began to hear the positive results of our test Marshall as it came to new life.
Now, in Part II of our continued Marshall JTM-45 transformation, we move forward with two additional changes in addition to having the opportunity to compare the final results to an original 1964 badge-logo Marshall JTM-45. The two changes that we decided to perform were to swap out the stock output transformer to a Mercury Magnetics™ (www.MercuryMagnetics.com) Axiom® O45JT-C model as well as to upgrade the board’s capacitors to those made by SoZo Amplification. To say that we were excited as well as just plain curious about the final results, especially when we could now compare it to an original JTM-45 — is an understatement.
We contacted Paul Patronete at Mercury Magnetics™ and he hooked us up with the Axiom® output transformer. Paul added that the Axiom® O45JT-C is a custom version output using Teflon wire instead of the normal UL1015 vinyl wire. The Axiom® O45JT-C output offers 8 & 16 ohm secondary taps. When it comes to output transformers for the JTM45 amp, Mercury Magnetics™ offers a plethora of options beyond the stock, cloned, vintage replacement. Options available in the Axiom® line of output transformers are primaries optimized for KT66/6L6/5881 tubes or EL34/KT77 tubes. Secondaries with just about any output impedance combination that one could want. Many of these custom Axiom® models feature “mil-spec” Teflon wire leads with silver tinned, nineteen strands of high purity copper. All of the Axiom® transformers are hand wound from period correct specimen, vintage blueprints. One of the more popular Axiom® pieces that Mercury Magnetics™ offers is an exact clone of the highly coveted Radio Spares output transformer. The Radio Spares output is from the early original, first run Marshall JTM-45 production amplifiers. Mercury Magnetics™ offers several versions of the Radio Spares output. One of the most popular versions is a Teflon wire leaded version. The Radio Spares transformer is well-known for its association with the earliest Marshalls and according to Paul is what you’d find in the famous Eric Clapton “Bluesbreaker”-era amp.
Those that have listened to or played through a properly running Marshall JTM-45 know the sound. It’s a smooth and naturally compressed distorted tone that when pushed will provide just enough crunch to know it’s characteristically a Marshall, but without any of the “buzzing bees” preamp tones characteristic in high-gain preamp-gain emphasized amplifiers. As you push the volume controls up higher on a the best JTM-45s, it’s clearly the sound of rock with its fat bottom end, lovely harmonic overtones, and sustain that sits well with the best blues and classic rock tones heard. All of this packaged in an amp that really is one of the most dynamic and player-responsive amps ever built.
The reissue JTM-45, while certainly not a “bad” amplifier on its own, really does lack much of the detail and smoothness that is really much easier to grasp and identify when heard. For example, the reissue JTM-45 in stock form would thicken up appropriately with the expected tube compression when turned up, but it clearly was not as smooth. There are definitely some tones that sound a bit “grainy” and edgy that a properly running original JTM-45 doesn’t have.
A project such as this JTM-45 reissue transformation offers an exciting opportunity for those serious about maximizing their tone, but either don’t have or don’t want to shell out the prices for the originals. As of this writing in early 2004, script-logo JTM-45s are commanding a minimum of $4,000 and the better examples are going for more than that. Our badge logo JTM-45 featured here generously on loan for the story has a value that may well be approaching $10,000 by today’s estimates.
With that aside, we should start out by saying that this is not a thorough “apples-to-apples” comparison between the two amps. To be 100% fair, ALL the components would have to be altered to the exact specifications of our 1964 badge-logo Marshall JTM-45 and that really wasn’t the point. The point of these transformations was to get the stock reissue JTM-45 sounding more like the “real thing” as described above with regards to the powerful, smooth and dynamic Marshall tone.
Another issue beyond the component values is that we’ve opted to keep the power transformer in stock form for the time being in the JTM-45. As a result the transformers will supply a different amount of B+ current to the plates and so it will not respond in exactly the same way as the original Badge logo model.
One final, and perhaps most important point, which Mercury Magnetics™ vice-president Sergio Hamernik added: “The transformer in a 30-year old amplifier will sound characteristically different as it ages compared to a new replacement, even if the replacement is built with the same materials.” And while the component materials and manufacturing methods used by Mercury Magnetics™ are made to the exact same standards as the originals (Sergio also added “Every turn, every layer, is copied and blueprinted exactly, including any original manufacturing anomalies found during our rewinding process of the original, vintage specimen, Sergio emphasized that the ToneClone™ series transformer will still sound different, but “like the original did in the amp when it was new” and not like the tone of the aged 30-year-old transformer. Since much of our favorite tones were recorded at least 20 years ago, perhaps this isn’t such a bad thing?
Sergio did suggest breaking in the new Axiom® transformer with 20 to 40 hours of hard playing time. He also said that this break-in period will get the transformer about halfway there to that 30 year seasoned tonality. Thermal cycling and running magnetizing currents through the transformer (playing the amp) will definitely sweeten things up in that period of time.
We could and may still make further changes to the reissue JTM-45 in the future and report back. However, with the point-to-point board, reduced “vintage” filtering, and tube swap that we performed last time around, along with the planned replacement of the on-board capacitors and output transformer for this second round, we thought that we’d be in really good shape with the final tonal results of this amp. And for those that missed it previously, we had previously written about Mercury Magnetics™ output transformers used in a 50 watt Marshall and were very pleased with the results. We anticipated nothing but the same results with the change in the reissue JTM-45 this time as well.
So far our project amp has KT-66 power tubes, 32x32uf and 16x16uf filter caps and a Metro Amps point-to-point circuit board. At this stage, we were very satisfied with the results. We could have stopped here and had a real tone machine, but we wanted to see if we could get even closer with a few more changes. Sonically, the reissue at this point prior to the SoZo caps and output transformer change, did exhibit more of the growl and gain of the original, but it still wasn’t nearly as smooth or as dynamically punchy as the badge logo JTM-45 was.
Mike Mullen on testing the SoZo Caps
While waiting for our Mercury Magnetics™ output transformer, I read about some capacitors that created quite a buzz on the Plexi Palace vintage amp forum. We found that SoZo Amplification was offering custom made capacitors aptly named “mustard caps”. They are obviously mustard yellow but apparently these caps are also made to the same specifications as the yellow mustard capacitors which were originally found in tube amps from the 1960s and 1970s. These little yellow jewels keep the foil thickness, polyester film dielectric and voltage ratings the same as the originals. In addition to the material makeup of the capacitors they also share the same physical dimensions. According to the SoZo Amplification website, the physical shape has a lot to do with the sound because it changes the slew rate.
The SoZo Mustard Cap is longer and thinner as compared to most high production caps readily available today. The additional length results in a different signal delivery time, changing the harmonics of the capacitor and yields smooth, clear, thick lower-mids. Polyester film was chosen because of its deeper tonal character and aluminum foil was chosen to exactly recreate the capacitor’s original sound and performance. SoZo also chooses to use tin-coated pure copper leads, which SoZo claims aids in the retro mustard cap sound.
I promptly received the package containing five .022uF and three .1uF SoZo Mustard Caps and soldered them in. In about thirty minutes all the caps were installed and I was ready to hear the results.
I flipped on the power, plugged in a Seth Lover-loaded Gibson Les Paul and let the KT-66’s warm for a few minutes. Turning off standby, I decided to start with my best impression of Angus Young from AC/DC to entertain my neighbors. What I heard from my Celestion loaded 2×12 cabinet was clear, warm guitar tones that sounded ALIVE! The tone of the amp was basically the same, but it was much clearer, richer and more complex than what I heard before. I was very pleased with the improvement.
Anyone that is due for a cap job on his or her favorite amp should really give the SoZo “mustards” a try and change those along with the electrolytics while you’re already there. I think the results are very satisfying and the cost runs about the same as a decent guitar cable. The caps can be ordered direct from SoZoAmplification.com or from MetroAmp.com. MetroAmp.com is offering these SoZo caps individually or they can be ordered with one of their point-to-point boards.
A final point is that SoZo amplification states that there is a break-in period for the capacitors and that the tone will actually improve and be at best form sonically sometime between 40 and 70 hours of use. While I’m not there yet as far as hours of use, I definitely like what I’m hearing so far!
Installation and listening to the Mercury Magnetics™ O45JT-C Output Transformer
The Axiom® 045JT-C output transformer is part of the Mercury Magnetics™ Axiom® ToneClone™ series, and is 100% hand wound in the USA by Mercury Magnetics™ at their factory in Southern California. Mercury Magnetics™ offers a number of transformer clones for JTM-45 amplifiers as Marshall used a few different suppliers during different times with its own JTM-45s originally. Some people may have a preference for the earliest transformer equipped in JTM-45s, which were those built by the Radio Spares company. According to Mercury Magnetics™, the Radio Spares output transformer has more “high-fidelity” characteristics in its tone. According to Paul at Mercury Magnetics™, their Radio Spares clone is a special, intricate transformer that produces a subsequently wider frequency response and in some ways mirrors other transformers in design such as the early famous Partridge units in the Hiwatts.
However with that said, there aren’t comparatively as many JTM-45s equipped with original Radio Spares output transformers so we went with the more commonly found transformers as found in later JTM-45s. When speaking with Paul, he also noted that the original, vintage “Radio Spares” equipped JTM45 amplifiers are highly sought after and can command big dollars in the musical marketplace. Perhaps we’ll experiment with one in the future to hear the differences for ourselves.
The installation of any output transformer, while seemingly “simple” (“hey there’s only a few wires right?”) should actually only be performed by either a professional technician or by an enthusiast with a minimum of Electronics 101 knowledge, including the ability to read schematic diagrams, an understanding voltages and polarity, etc. This is the advice directly from Mercury Magnetics™.
The transformer includes a wiring diagram sheet listing the color-coded primary and secondary wires, and these may not necessarily match the wiring in your amp. Mercury Magnetics™ also warns that installers put safety first, as there are literally hundreds of AC volts that can come off of the primary. A typical technician will charge 30 to 90 minutes of labor for the installation, which can average anywhere from $50 to $150.00. Prices and the time required to install an output transformer can vary from technician to technician.
*Installation tip: anyone planning to replace both the output transformer and circuit board may want to remove the old circuit board and output transformer first and then mount the new transformer. Then you can install the point-to-point board and not have to mess with it later to get at the output transformer mounts.
After some time and with the transformer installed, it was time to play! But first, a few minutes with the badge-logo JTM-45….
Taking a Classic for a Test Drive
The original badge-logo Marshall JTM-45 is truly an example of a wonderfully responsive guitar amplifier. In its best state, it can provide a range of tones that vary between the liquid and thicker lead tones of early Clapton, to the warmer side of the Marshall crunch a la AC/DC that we all know and love. The vintage badge-logo JTM-45, that we have the good fortune of borrowing courtesy of our good friend Woody (thank you!), had recently gone through a full check-up through southern California’s own Plexi Palace, so we knew that it was in fine form.
And it certainly sounds like it. No other Marshall seems to be as well suited to provide such a wide tonal range as well as being able to provide a feel with beautiful harmonics and compression as a JTM-45 circuit. The sense of dynamics that can be controlled with one’s technique was right on the money. This JTM-45 plain and simply is THE ultimate blues and rock amplifier.
It stings and bites as musically as one could imagine with a Fender Stratocaster using the bridge position pickup with the Marshall’s channels bridged and the volumes set at about 7. With the neck pickup, the tones are fluid and with a bit of a gain boost from a floor box could easily capture the full sustain similar to what a player like Eric Johnson would get. The power output on the amp is moderately high, but at the JTM’s power range, it really is a nice match against any solid-hitting drummer and the perfect club amp for small and mid-sized venues.
With a Gibson Les Paul in hand loaded with LegendaryTones.com’s current favorite Seymour Duncan Antiquities and running the badge-logo JTM-45 through a basket weave Marshall cabinet (NOT the cabinet photographed here which is an earlier pinstripe) with original 25 watt greenbacks, the tone of the bridge pickup was pure AC/DC circa “Powerage” when running the volumes at about 6. With the volumes set at 7, the added gain and thickness moved into “Highway to Hell” territory. Switching to the neck pickup provided a wallop of a fat tone that seemed like it could sustain for days. Think early Cream here.
Listening in on the reissue JTM-45
After that experience with the 1964 badge-logo JTM-45, part of me didn’t want to turn the amp off, but alas it was time to move to our modified reissue. Running the same controls (and in fact the same tubes were used and setup in both amps) and equipment, I started playing the reissue with the Strat first. The immediate first impression: the reissue JTM-45 felt great – the same feel of compression and control of the dynamics was there. And there was also a noticeable improvement between the circuit since the change of both the output transformer and SoZo caps. Besides having a bit more power and punch in the signal, these changes really seemed to smooth out the reissue JTM-45’s tone and were definitely much more pleasing to the ear.
But specifically what were the differences between the reissue and the original? Well, the modded reissue stood out with a bit more attack in the high frequencies. It’s definitely a bit of a brighter amp than the 1964 badge-logo, but not by a great deal and not bright in such a way as to be “piercing.” The reissue JTM-45 could definitely mimic the original with a simple reduction of presence and treble controls and it did very well. Also, both SoZo Amplification and Mercury Magnetics™ told us that there is a break-in period for the parts to obtain their final adjusted tone. Again, for the SoZo caps, its 40-70 hours, and Mercury Magnetics™ stated the average break-in period should be a minimum of 20 hours of hard playing time with its transformers.
All said, we couldn’t wait that long nor did we have the time to play continuously to then report on the changes, but maybe we’ll add a brief report in the future after the break-in period.
When switching to the Les Paul with the newly transformed JTM-45, the same characteristic bold crunch with a warm full bottom end was evident. The modified reissue JTM-45 is definitely smooth when overdriven and power chords are a thrill to bash out in AC/DC style. Leads in both pickup positions of the Paul sang nicely. The neck position is always powerful with the JTM-45.
Final Thoughts….
In both amps, the feel, sustain, and tone was tremendous. The reissue in its current form has a little bit more of a faster attack, while the original badge has a bit more of a relaxed sag to it characteristically. It’s also a little bit darker. That said, we expected differences especially considering that each amp’s circuits are not identical. But what they do both share together is the original Marshall tone that we grew up on and know and love. And the fact that this tone can be captured without the need to hunt down a costly original is a nice thing for players indeed. There is something to having an original — it’s a testament to a wonderful period of musical history that NO reissue would ever be able to capture from that perspective. But at the same time, one thing that the reissue has going for it in its favor is the fact that most players would feel much more comfortable taking it out to a gig or the all-night jam. I would be a bit paranoid taking out the original personally.
It’s a shame that some of our greatest musical instruments, whether we’re talking about a ’59 Les Paul or an original Marshall amp, are so highly-valued in this day and age that it’s difficult to “enjoy” playing them. However, isn’t it a nice thing that companies such as those featured in this article are so passionate about their products and in finding ways to empower musicians with great tonal solutions today? I’ve said it before — we’re definitely living in times of a tonal renaissance with the options we have and the number of great instruments, effects, and amps that we have available to us.
And though some people may say that, “they don’t build them like they used to,” I would actually agree. In the case of these dedicated companies and people, I believe they’re in fact building them better than they used to with care and meticulous detail that may not have always been present back in the day.
Source: https://mercurymagnetics.com/pages/news/LegendaryTones/LegendaryTones-02.htm
Somewhere along the way, guitar amplifier tone got carelessly shoved into two broad categories – American and British. Fender being the quintessential American tone and Marshall being the obvious default for midrangey and reverb-less British tone. Within each, of course, there are distinct variations… Ampeg, Magnatone, Valco and Gibson, for example, are also American through and through, yet they remain distinctly different in sound and construction, and would rarely be mistaken for a typical Fender. Among British amps, Hiwatt, Sound City and Vox present equally diverse varieties of “British” tone that won’t be confused with a classic plexi Marshall head. But simply adding reverb or delay to a British amplifier will often throw listeners completely off as to its origins, while plugging into the Normal channel of a vintage Fender brown or blackface amp with the right guitar can produce an exceptional “Marshall tone.” Our recent experiment with our ’62 brown Vibrolux and a Goldtop Deluxe Les Paul with Lollar mini humbuckers rammed this point home with alarming clarity…. The point is, labels don’t always serve creativity and discovery well, and in the realm of supposed “vintage amp tone” where different examples can vary so dramatically, labels are worthless in generating much more than “skull chatter,” to quote Kye Kennedy. But, we still crave “Marshall tone,” whatever our individual perceptions of that sound may be. Well, since you asked….
ZZZZZZZZZZZZZZZT!Yes, Gear Page wankers, we just did it again. Careful you don’t get a scab on that thing… it might get infected and fall off. We’ve unearthed two alternatives that will give you the bigger, bolder version of Marshall tone that you remember from your early Jeff Beck Group, Zeppelin and Cream albums, but at a volume level you can easily live with and actually enjoy in 2008.
A reader alerted us to Roy Blankenship, oh, about a year ago, and it took that long to get an amp shipped for review and develop an interview. It was worth the wait. Blankenship builds a manageable range of custom amps in Hollywood, and he seems more interesting in building what he wants, the way he wants, than going big time. We like that. So here’s an introductory dose of Roy Blankenship – an entertaining and frank fellow to e sure. Our review follows Roy’s interview.
TQR: Can you summarize your experience with electronics and guitar amps? How did you get started initially with mods and repairs, and how did that evolve into actually building your own amplifiers?
RB: First, I was born in California. My father worked for North American Aviation, and was transferred to Columbus, Ohio when I was 6 months old. Therefore, I was born crazy, but grew up normal. My father was a genius – he could build anything, and, in fact, he built my first guitar amp. It was a single-ended 6L6 design and had a field-coil speaker. It wasn’t loud enough to play in a band, but I still have it and it still works. I later discovered the cabinet he used was the extension speaker for an old film projector.
I started playing piano when I was 3, and played brass instruments in the school band. When I was a Junior in high school, I bought my first guitar. A Kent solid body, for $49.95. I finally convinced my dad to let me buy a Health kit 2×12 solid-state kit so that I could play out, and that was my first experience with electronic assembly. I was the guy in the band who would dick with all of the equipment. We bought some PA cabinets that had JBL’s in them, I refinished and rewired them, having no idea what I was doing, but it always worked. My dad had a whole workshop including lathe and drill press, so I often did small projects and repairs, like building my own speaker box to house two Jensen 6×9 speakers for the car. I wish I would have had the vision to go into production….
I was a hobbyist for the next 20 years, getting into tube hi-fi and going through a dozen Dynaco Stereo 70s, not knowing anything about them, but doing little stuff like biasing and tube exchanges. I was employed in the music biz as a sales rep for four different firms, and the pinnacle of my career was as national sales manager of Symetrixin Seattle, WA. In 1991, I had a three-state sales territory selling body shop equipment. I stopped to see my friend, Dan Abell (of Abell Audio, 909 King Ave., Columbus, OH), best tech in the world, and drop off some octal sockets my dad had left me. Dan was all upset and expressed that his assistant had quit that day and he was in a bind because he had so much work. On a whim, I said, “Hire me. I have always loved this stuff.” “Can you troubleshoot a circuit?” I said, “Not yet, but I have people skills and can do any number of things so that YOU can work.” I knew his assistant wouldn’t answer the phone or wait on customers, so, after the first day, Dan said,“Man, I can’t believe how much I was able to get done. You’re hired!” Within two weeks, I was repairing circuits. The info that opened the door was the difference between negative and positive polarity transistors. We worked together for the next four and a half years, never an angry word between us. At one point, I wanted to live in California, so I went to a NAMM show and was hired by Groove Tubes as production manager. The learning curve was straight up – there is an incredible amount of information in that place. From there I started my own place in Santa Monica. To escape the chaos that is L.A., I moved to Florida to escape. I realized the repair biz was not a big money maker, so when two clients started encouraging me to build my own designs, I was up for it. We beat it around fora while, they finally ponied up and I built two EL84 amps.They loved them, I was shocked (they were nothing special),but they were the start. I still have number 1 that I bought back from the third owner. My experience with amp repair changed when I came to L.A. People in Ohio and Florida were happy when their amps worked… players in California wanted their amps to sound good. That opened a whole new area of learning. About the same time, I was running into a lot of overly-modified amps that oscillated themselves to death, so I added “demodification” to my business card. People would call me back and say, “Man, this amp really sounds great now,” and I would reply, “Yes, I made it stock.” The only mods I deem worthy are tone-stack bypasses on Fenders and one of two master volume circuits that actually work well. They each allow you to attenuate volume without losing everything, and they both originated with Ken Fischer, amp guru, God rest his soul. Tube amplifier technology stabilized in the mid ‘60s, and very few amp builders have done anything innovative since that time. In order to separate myself from the pack, I wanted to improve on the existing circuits. When these amps were made, people were playing clean, now everyone wants to crank them up,and in order for them to deliver, my belief is that they need a stiffer power supply. I get a lot of comments on how “loud” my amps are for a given wattage rating. One client said, “I have played a lot of these amps, they give up when you hit them, but yours sounds like a big amp.”
TQR: Describe the different models you build in terms of features, construction and tone, how they differ from vintage or other custom built amps, and what you specifically wanted to accomplish and/or improve on with each model.
RB: I build my own take on American and British circuits,and I employ a stiffer power supply than most. I am currently using turret and eyelet board construction, but a printed circuit board can be useful if made properly. The compromises made by volume manufacturers is where the “circuit board-is-bad” myth started. Proper CAD design can lend itself to a quieter, more reliable product as long as the bean counters don’t try to take a nickel out of it at every turn. All of my current product is hand-wired, and as you know, there is a lot of snob appeal and dick-measuring in this business. For example, some of my clients wonder why I do not use Clarostat potentiometers… I have tested all of these devices, and I have never had a bad Alpha pot, but the Clarostats I ordered for testing were 50% defective!
In the Leeds amp, I went with different trannies than most and a stiffer power supply; this gives it more beef. In the Fatboy, I discovered an output tranny that would allow me to use 6V6’s (for 15 watts) or 6L6’s (for 25 watts) without changing the speaker load. Though the tranny was originally designed for an 8 ohm load, it actually worked more efficiently at 16. Overall, using Mercury trannies has been one of the best decisions of this whole venture. Now when I hear an amp with any other tranny, they sound flat. I took one of my amps to visit a friendly competitor, he played it and enjoyed it, then fired up his own amp, and it sounded flat. He was looking at his amp as if,“Hey, what’s going on here?” I think that was his first side-by-side comparison and he could hear the difference, much to his own chagrin.
TQR: What inspired the use of a Variac with the VariPlex? Why not just build a master volume circuit?
RB: We wanted to create a cranked-up Marshall sound at lower volumes, but people have time and again expressed their dissatisfaction with the attenuators on the market and the smashed sound of a bad master volume circuit. I credit Dave Friedman of Rack Systems with the concept and the prototyping. We tried five different kinds of coupling caps, different types and brands of resistors, different trannies…you name it. Eddie Van Halen popularized the whole Variac concept, so we modified the circuit so you could go from full tilt boogie down to 1 watt and the amp would not shut off. We have sold 40 of those amps with no marketing other than clips on a forum. We are now introducing a similar amp with a master volume for those who want it whisper quiet, but saturated. There are two master volume circuits that I know of that sound great even when turned down to speaking levels. We are using one of those and a few other mods in the new model, the Custom 45.
TQR: You describe a process on your web site in which you A/B’d the VariPlex with a friend’s ’68 Plexi and you didn’t stop tweaking the design until 10 out of 10 guitarists chose the VariPlex in a blind test. Can you elabo-rate on how those tests progressed and the changed to the circuit that you made to achieve those results?
RB: I could, but I won’t.
TQR: In your experience, how much variation in tone and component values, including transformers, have you observed in vintage Marshall amps? Isn’t it necessary to listen to a lot of different examples and then choose an exceptional amp as a benchmark?
RB: Yes. We already had “the Holy Grail” plexi in house, so we compared to that one. Most amps will respond to love, but there are some that are just exceptional. The reason for this amp-to-amp variance is manufacturing tolerances. If your trannies are built with plus or minus 20% tolerances, that means your amp could vary as much as 40% from sample to sample.
TQR: The VariPlex doesn’t sound “new” in the sense that it isn’t shrill or bright and sharp like some replica Marshall amps. How did you accomplish this?
RB:That’s my secret.
TQR: How long is the wait for one of your amps once it has been ordered?
RB:We have Carry-Ons in stock for the first time. Generally, we like to say 3-4 weeks just to be safe. Most of this is the gray area of vendor delivery on cabinets.
TQR: What’s ahead? What do you want to accomplish in the future?
RB: I want to be a thorn in someone’s side so they will offer a butt load of dough, I will sign a non-compete, and go away. Then, I can sit on the beach and light my cigars with $100 bills and sip pina coladas. The funniest thing about that picture is that I don’t drink OR smoke. Actually, we are introducing a bass amp shortly. As we gain more exposure, I am sure we will have enough to do. I am happy with people’s response to my products. I do not want to get huge, and I will probably not offer many more models – it gets too confusing. But thanks for considering me as a worthy contributor to your magazine. www.BlankenshipAmps.com (818) 530-8853
Our experience with “vintage Marshall tone” was formed with two stout examples that we were fortunate enough to own and play for years. The first was actually a late ’60 Park ’7550 watt head, followed by a metal panel 1969 Marshall50 watt. Both amps displayed the classic tone, smooth distortion and touch-sensitive dynamics we love to love and eagerly oozed the warmth and dimensionality that reissues lack. This isn’t complicated…. We’d simply drag a newish Marshall clone of some sort into the music room, compare its sound to the old one and invariably say, “Not bad, but this one sounds and feels better.”
When we fired up the Blankenship, however, not only did it sound richer and fuller with more depth than our old Marshalls, but the tone controls actually produce changes in EQ that allowed the amp to achieve a level of versatility that has always been sorely lacking in the originals. And then, of course, there is the nifty Variac that allows the VariPlex to be played at nominal volume levels with no audible deterioration in the responsiveness or tone and the amp. Essentially equipped with features that mirror an original Plexi, the VariPlex is a 2 channel/4 input design with presence, bass, mid and treble controls. Channel 1 is the bright input; channel 2 is more bassy, and the two can be jumpered and mixed to taste.
We took our time developing an impression of the VariPlex, playing it for over two months. Bottom line – it produces an authentic, old-school Marshall voice with better EQ, clarity, and fresher, more vivid harmonic content. Its voice is exceptionally smooth, yet capable of acquiring the melancholy edginess of an early Clapton recording by simply managing EQ, and the Variac as a master volume control works brilliantly. The VariPlex impressed us as a near-perfect example of an overbuild, hand-wired, low-production amp inspired by arguably the best efforts of Jim Marshall and company, circa 1968. Just as the Balls M18 became our modern benchmark for low-powered, classic Marshall tone, so goes the Blankenship VariPlex in the 50-watt range. If there is a better-sounding modern alternative toa vintage Marshall, we have yet to hear it.
We also admired the neat, clean and easy-to-read design of the VariPlex silver control panel, somewhat reminiscent of our old Park. Among all the clones being cloned with Mojo boxes, this amp is a visual standout. And as far as internal build quality is concerned, let the pictures speak for them-selves. In all respects the VariPlexis a solid piece of work,returned to the builder with as much regret as any amp we have ever reviewed. In fact, we’re still thinking about it. Plex forth….
It was originally built around the design of one of Jim Marshall’s favorites, the Fender Bassman; like the Bassman, the JTM45 was actually a fantastic guitar amp. Because of its consistent popularity, Marshall has offered a reissue version of the head — more than 20 years after production of the original JTM45 ceased. While the reissue is built with modern components and assembly techniques, it retains much of the tone, responsiveness and character of the original, hand-wired versions of the early days. No wonder builders today still carry on the tradition of the JTM45, and guitarists continue to seek out the pure simplicity and touch response of this tone machine. To celebrate the JTM45, I got together with my Sunday afternoon amp group, after contacting a handful of respected amp builders who sent us their versions of the amp. We fired them all up alongside an original and a reissue JTM45 to take a listen — and to enjoy one of the best amps ever designed.
About the Authors
About 5 years ago, while playing a 9/11 benefit show, I had the good fortune to meet two people who would not only profoundly impact my life with tube amps, but would become lifelong friends. John Rossi and Tony Burns were there that day; Tony, a killer player and a regular on the Tempe/Phoenix music scene, and Johnny, his friend and amp tech, making sure Tony’s amps were running well in 115 degree heat at the outdoor amphitheater. When I saw Tony’s wall of Marshalls next to my backline of Marshalls, it was an instant conversation starter.
We spent time between sets that day discussing the various finer points of our amps and gawking at each other’s rigs. The show went great but my ’67 Super P.A. felt a bit stiff, and wasn’t reacting in the most flattering way. This incident proved to be the catalyst, as Johnny was an underground semi-retired tech and ultra-fanatic Marshall enthusiast, and he had some ideas that he wanted to try out. He invited me over the following Sunday to check out the amp, and to experiment with various preamp and power amp tubes while BBQ-ing and having a beer. Tony was there, and it became clear that we all had a deep respect for these amps; rather than modify them, we wanted to bring them back to their former glory. After five years, and dozens of hacked-up Marshalls coming back from the dead, here we are. Over that time we’ve learned more about these amazing amps than any of us ever anticipated, and we’ve have had a blast in the process. I have no doubt in my mind, based on my readings of the various amp forums, that there are plenty of groups just like us all over the world doing the same thing.
The Lineup
The lineup consisted of our own 1965 original and 1990 reissue heads, two MetroAmp JTM45s (a kit version as well as the GPM 45), a Germino Classic 45, a Wallace Amplification BKW45 and Mojave Ampworks’ new Special Edition Plexi 45 head. After searching through our collection of cabinets, we settled on both an eighties Marshall JCM800 4×12 with black back 25s, and a Mojave 2×12 cab with 1963-era Celestion Alnico Blues. It may sound strange that there were no pinstripe or basket weave cabs used for the roundup, but that wasn’t for lack of trying. Among all the members of the amp group, we actually have a pinstripe, a basket weave and a variety of Marshall 4x12s, but for some reason we always come back to the early-eighties JCM 800 cab with black back 25s.
That particular cab has more clarity, tone and authority than any other, and it remains our favorite in the bunch — despite the cool factor of the older cabs. The 2×12 with Blues was a natural choice, as that flavor shares similarities with the mid-sixties Marshall cabs and is also a popular speaker configuration for Bluesbreaker combos. The guitars we used were our standard array of Les Pauls from the ’70s, ’80s and 2000s, as well as a newer 2008 Fender Strat and two early-seventies Strats. With everything in the room (it was quite a sight!) we were ready to begin.
Original 1965 JTM45To get our ears accustomed to the JTM45 sound, we began by firing up our ’65 head with a Les Paul. Normally, this head has EL34s in it, but we borrowed the Genelex KT66s from the Mojave and biased the amp to accommodate them. It made sense to us to use KT66s, because they were what the amp was designed for. With everything looking good, we flipped it from standby and beheld the beauty of this vintage masterpiece. It’s no wonder players and collectors are paying big bucks for these amps; everything we played through it sounded incredible.
What was amazing was how much of a rock ‘n roll amp this really is. Considering how long it’s been since it was conceived, the amp’s sound remains surprisingly current. The distortion is organic, full-bodied and earthy, and it allowed the personality of the guitar and player to shine through. While it was very easy to play, this is an amp that still requires a level of discipline and control to fully harness its capabilities. It makes sense that players who want to be heard would play on this style of amp, because like it or not, whatever you play through the amp is… well, amplified. It just comes out better.
We played through it for a good long time, switching guitars and speaker cabinets to hear it in as many different configurations as possible. Whether it was a Strat, a Les Paul, a 2×12 or a 4×12, the sound was always remarkable — perhaps the very definition of great tone. Subjective? Yes. Brilliant? Absolutely. Rolling back the volume on the guitars exposed a beautiful clean tone that was harmonically rich and defined, never muddy or dull. Even with the guitar’s volume knob all the way up, the dynamic response of the amp, and the way it musically fed back, was awe-inspiring.
Once we had established a base tone for comparison’s sake, it was time to play and listen to the other amps. Before I break down each individual amp and builder, I must observe that each and every one of the amps had ridiculously good tone, and they all sounded like JTM45s, but each had its own unique voice. Aside from the reissue Marshall, all of the amps are hand-wired. The reissue Marshall was of PCB-construction, and used the standard parts and components that Marshall was building their amps with during that era. I spoke with Mitch Colby from Korg USA (Marshall’s US distributor), who told me that the reissues have not undergone any significant changes since their reintroduction 20 years ago. While they are using the components that Marshall builds with today, they should yield very similar tones to the earlier reissue amps.
George Metropoulos is no stranger to the world of Marshall amps or to the online amp building community. Having run MetroAmp for some time now, George offers everything from fully built replicas of many classic Marshalls to ready-to-build kits and hard-to-find replacement parts for vintage Marshalls. A player, George honed his amp-tech skills by adopting a DIY approach, taking care of his own amp repairs on the road. This extended into repair work at home, and then really took off when amps began coming in for restoration rather than simple re-tubing. After his ’73 Super Lead was stolen from a gig, he realized it might be best to leave the valuable amps at home, and so he embarked on a never-ending quest to replicate the tone of the old Marshalls.
Like all the builders in the roundup, George is passionate about vintage Marshalls and obsessive over the details that make these amps so coveted. We received two amps from Metro: the JTM45 kit (which can be purchased already assembled for an additional $400) and the GPM45, George’s custom-built JTM45 using NOS vintage parts. When we fired up the MetroAmp 45s, it was clear that they both came from the same camp. Both amps were meticulously built and incredibly precise in their layouts. The main physical differences between the amps came down to the caps, resistors and tubes. Both amps shared the same iron and layout, so they also shared a lot of the inherent tone in their circuits. As George is a fan of the mid-sixties JTM45s, Metro’s transformers are based on the Drakes, rather than the earlier Radiospares iron [editor’s note: Kit also comes with optional Mercury Magnetics transformers]. Still, there was no question that the GPM45, which included NOS Phillips mustard caps, Allen Bradley carbon comp resistors and a gorgeous set of Genelex KT66s, was sweeter sounding.
While those differences accounted for a tonal upgrade, what made the differences even more compelling was the way they affected the touch factor of the amp. Much like our ‘65, the custom-built Metro had an ease about it that felt like a broken-in vintage head, making it a breeze to dig in, or to lay back on the strings and feel the amp act as an instrument. It was truly inspiring. Of all the amps in the roundup, this amp sounded most like our ’65 — frighteningly close! I should mention that the Metro kit version was actually plugged in first, and before comparing it to the GPM45, we all agreed we’d be thrilled to have one in our collection. We may be splitting hairs here to some degree, but knowing that anyone can buy a complete kit for under a grand, and have that kind of quality and tone — that says a lot.
Metro’s JTM 45 Kit:
Metro’s GTM 45 Custom Build:
Wallace Amplification BKW45Brian Wallace has electronics in his DNA. His father, an electronics engineer, and his grandfather, an RCA tube repairman, were both instrumental in his early education and development in tubes and electronics. When he was young his father gave him a 75-in-1 electronic projects kit and further encouraged Brian by letting him watch as he built his own projects. Like all of the builders in the roundup, Brian is a player. He began modifying amps in 1974, when he removed the speakers and baffle in his Checkmate amp and replaced them with a baffle he created and some purchased speakers — altering the sound of the amp and thus beginning his lifelong journey. In 1995, he was approached by Guytron Amplification to help out while they were getting started. A positive experience, it propelled him to the next level and led to the creation of Wallace Amplification, which now offers several amp models as well as replacement transformers under the Marstran name.
Wallace’s first amp is the BKW45, but he is more than a clone maker. Recently he introduced the Abaddon, which is a 50-watt master volume head consisting of four gain stages in the preamp. There is much more to come, including a line of pedals and a reissue of the Fuzz Ace pedal he made back in the early ’90s. The BKW45 is a unique flavor of JTM45. A hair darker in tone and possessing slightly less gain than all of the other models, including both the vintage and reissue Marshall, it yielded enormous bloom and a bold, thick, sustaining quality. Even though there was a little less gain, it didn’t affect playability, and we never struggled with the amp. It was one of the rarest qualities I’ve experienced in an amp, and certainly an unexpected bonus.
The Wallace had a magical ability to push notes through loud and clear while still being able to dish out gritty and harmonically pleasing chords that didn’t fight the non-perfect intervals they were built on. This all came out of an amp that was using tubes you can buy today without breaking the bank.
Speaking of breaking, check out the sidebar on what the BKW45 was subjected to by UPS en route to our roundup. In spite of the gorilla treatment it received, the amp arrived without shattered glass and performed flawlessly throughout the entire set of three sessions of playing and listening. That’s a testament to a solidly built and roadworthy piece of equipment. And one look inside the amp will show what a dedicated and precise builder Wallace is. In tone and build quality, the amp is a work of art.
Ever wonder what could happen to your amp in shipping? In the case of Brian Wallace’s BKW45 amp, UPS had a field day, and decided it would be a lot of fun to throw it around. When the amp arrived, it was packed neatly in a new cardboard box with padding inside suspending the padded road case that housed the amp. That’s double-boxed and protected by a case built for heavy abuse. Sadly, it took one good slide down the end of a ramp and collided with either another box or the wall of the truck. Though the box didn’t show any signs of abuse on the outside, it was clear that something had shifted when I opened the case. Take a look at this picture of the damage and the way the entire amp was shifted to one side because of the impact. Believe it or not, the tubes didn’t shatter and the amp worked fine, but it was cosmetically damaged by a broken front Plexi panel. This isn’t the first time this has happened, but it’s the first time I’ve seen it happen with this type of road-worthy packing. Let this serve as a reminder to always insure your amps, as the shipping company can’t tell if you’ve got a bag of peanuts in a box or an amp that was lovingly built by somebody like Brian.
Germino Amplification Classic 45Greg Germino is another lifelong guitarist who was bitten by the tube-amp bug after catching the Allman Brothers Band back in 1972. He was so inspired by that show that he switched over from acoustic to electric guitar and began taking electronics classes in high school. In 1979, he requested schematics from both Ampeg and Unicord (Marshall’s US distributor at the time) and began his hands-on education with tube amps. He spent the ’80s at an electronics job, and by the early ’90s he was moonlighting doing tube amp repair for a few music stores. He continued to play live with both 50W and 100W Marshalls during that time and moved to Durham, NC to work at Bull City Sound — working on tube amps from the big-name amp companies.
This led to Greg’s being commissioned by Mojo Musical, where he built their Tone Machine amplifier. The following year, 2002, he began work on the prototype of his Lead 55 amp, which debuted in May of 2002. The Classic 45 model is based on the earlier Radiospares-style output transformer, rather than the Drake 1202-103used in the ’65-’66 era, and the circuit is exactly what you would find in an earlier original. The Radiospares-style OT is supplied by none other than Chris Merren, who is highly regarded in the world of Marshalls, and known to make some of the most accurate transformer replicas out there.
The Classic 45 was the only amp in the roundup that used 6L6 power tubes. Greg’s decision to use them was a combination of staying true to the earliest tubes Marshall used on the original JTM45 amps and his belief that the current crop of 6L6s sound and perform better than newer KT66s. NOS and vintage 6L6s are also less expensive and more plentiful than NOS KT66s. Our immediate response to the Classic 45 was that it was a lively and aggressive amp, with tons of power that made the pick explode off the strings. In ways it reminded us of our favorite ’67 Super Bass in its volume and attack, but it still retained the sound of a 45. It may very well have been the loudest amp of the bunch, and that volume translated to a feeling of excitement that made the amp extremely fun to play. It was present without being shrill and had a super-tight bottom end, no matter what guitar we played through it. While the Classic 45 had tons of natural gain on tap, it also cleaned up nicely when rolling back the volume on the guitar, revealing a bright and sparkly chime. This amp is a real beast, and it could hold its own against 100W amps without flinching.
Mojave Ampworks Special Edition Plexi 45Anyone familiar with the JTM45 would surely be jealous of Victor Mason. Not only has he seen more than his fair share of vintage Marshall, Vox, Hiwatt and other rare treasures come through his shop, but Victor recently acquired 26 of the all-time greatest JTM45s ever assembled via the Kronemyer collection, and he’s got the pictures to prove it! This is just one of the factors contributing to the obsessive nature of Mojave (and the associated Plexi Palace). Having been around for over a decade on the internet, Vic has been repairing, restoring, buying and selling vintage Marshalls for quite some time now. Stemming from his early desire to find out how EVH created the classic brown sound, Victor embarked on his journey through countless hours of digging into vintage amps and learning where their strengths and weaknesses lay. Mojave now offers an entire line of amps to serve the classic Marshall tones and well beyond with innovative features and designs. The Mojave Plexi 45 also has two very unique features over a stock JTM45. First is a simple feature to allow volume control by way of throttling the power level. Second is a line level output, which is adjustable and incorporates a ground lift.
Standing apart cosmetically from the rest of the amps, the Special Edition Plexi 45 is built on the same footprint as the Coyote and Scorpion designs, with a white-and-black color scheme and chrome hardware. The head is built with an open grille cage that allows for maximum airflow to keep the set of completely NOS glass cool. The 45 supplied for the roundup consisted of a pair of 1970 NOS Genelex KT66s, 3 Mullard 12AX7s and a Mullard GZ34. Like the Germino, the Plexi 45 is based on the Radiospares transformers, which are custom wound by Mercury Magnetics.
The chassis is a thing of beauty; the .09″ thick aluminum, with a high tensile strength and welded edges and seams will ensure it will not flex, bend or develop fatigue, like the early, folded, softer chassis, and will prevent the heavy transformers from causing the chassis to sink in and sag. Mojave deviates from the original JTM45 by using modern, tight-tolerance parts. Custom manufactured caps and metal film resistors allow each amp to sound as close to the one built before it as the one after it. Consistency is something that Vic definitely strives for, and it shows in the build quality and attention to detail, and the desire to add convenient functionality to his amps.
We found in testing that not only did the amp have an extremely low noise floor, but that it was an authoritative and powerfully voiced amp. There was definitely something different in the tone of the Plexi 45; it was cleaner sounding, but still very bold. Having been to Vic’s shop, I was fortunate enough to play one of the 26 JTM45s he had acquired, and I’m positive that the experience with those amps had more than a little to do with the design of the custom Mercury Magnetics’ Radiospares transformers made for his Special Edition model. The amp is built like a tank.
Marshall Reissue JTM45While the reissue looked very similar to the ‘65 on the outside, especially due to the fact that it’s already 20 years old, the differences on the inside were quite pronounced. Assembled with more modern methods, and using a PCB rather than hand-wired turrets, you could easily be fooled into thinking that it wouldn’t perform like the others. This particular amp was the only one in the bunch to use EL34s rather than KT66s or 6L6s, so the sound was definitely different. It was incredibly loud and focused sounding, and actually had many of the characteristics of a Super Lead. The sustain and power of the amp was incredible, and for an amp that can be found used for around $1000, this is a sleeper bargain. Marshall has taken some flak for their amps sounding stiff and cold from the factory, but with a little attention — slightly hotter bias and good tubes — this amp is a monster. And just because it says it’s a 45-watt amp, don’t harbor any illusions that it would be a good bedroom amp. This is a loud and powerful beast, and a tone machine as well.
The Blindfold Test
As a final, fun test, we did a blind study, to see how accurately I could identify each of the various amps in the roundup. Johnny and Tony set up the group of amps, and I sat in a chair with my back turned away from them. With the guitar plugged in, they began to fire up the various amps, and we got rolling. Out of all the amps, I was always able to distinguish the Wallace BKW45, due to it’s slightly darker sound. The Metros were also fairly easy to spot, but I ended up guessing the kit as the custom build and vice-versa. The ‘65 was also an easy amp to recognize, but as ear-fatigue set in, the lines began to blur substantially. Pretty soon, I was confusing the Germino for the reissue JTM, the Mojave Plexi for the Wallace, and the Metros for the real JTM. It just goes to show you that all of the amps performed remarkably well, and you can be fooled when you’re not seeing what you’re playing, so never discount a PCB reissue head as a second fiddle to the real thing. In the mix of a band, these differences become small, and any one of these amps would hold their own any day of the week.
Wrapup
To have the opportunity to play through so many variations on a classic theme was not only fun, it was educational. Each one of the builders excels in creating their own unique version of the great rock and roll amp that Ken Bran, Dudley Craven and Jim Marshall built back in 1962. While like all Marshalls, the JTM45 went through changes in tubes, components and designs over its lifetime, there is a trademark flavor and color that still can be found in all of them. Not everyone can afford a vintage 45, but with the help of these builders we have the opportunity to get into that sound and have build quality that will last for years.
Source: https://mercurymagnetics.com/pages/news/PremierGuitar/PremierG-20.htm
VG: Tell us a little about the background of Mercury Magnetics?
Sergio Hamernik: Although Mercury was founded in 1954 it was around 1980 that we fully recommitted ourselves to designing and building transformers specifically for tube-based electric guitar amplification.
Most of us know that by the late 1970s the audio electronics world was going solid-state. Although it now seems absurd, back then tube-based amplification was being abandoned. We were amongst a relatively small group of hold-outs. We were also acutely aware that if someone didn’t step in to preserve the technology that decades of know-how (not to mention the essence of tone) would be lost forever.
We put out the word about Mercury’s mission and immediately began to work directly with a select number of top players and amp designers who were like-minded.
VG: Who came knocking?
Sergio Hamernik: We were surprised that much of the early interest came from British artists. They had the resources and seemed to understand the transformer connection to great-sounding amps. But it didn’t take long for the word to spread. Soon artists from all over the world were bringing us transformers from their most prized amps to study and clone. The feedback from this period set the pace for Mercury and we haven’t strayed since.
Today Mercury’s friends and customers include pretty much the entire upper echelon of professional players and recording studios. In the builder community our friends range from the legendary Alexander Dumble and Ken Fischer, to passionate enthusiasts building amps on their kitchen tables. I’ve always been amazed at the caliber of talent we’ve attracted and the level of interest in our goals.
VG: How did Mercury determine which transformer designs had superior tone?
Sergio Hamernik: Think of what we’re doing as transformer archeology — not unlike opening ancient scrolls for the first time. Over the years we’ve unearthed some real sonic treasures!
Artists and amp collectors continue to bring us transformers from their most coveted amps to analyze, restore, duplicate or upgrade. They’re hard-won converts because they’ve all tried other replacements only to discover that the magic was gone.
By tradition, transformers have always been hap-hazard and inconsistent in design and build quality. Many of these amps were the freaks, factory prototypes, or often with one-of-a-kind transformers that just blew everything else away.
These are the transformers we have always been most interested in studying. Unfortunately, when it came to analysis, we discovered that the conventional methods only gave us a piece of the puzzle. Mercury had to devise its own proprietary methods of determining what made these outstanding transformers sound so amazing. Their “recipes” if you will.
“… if someone didn’t step in to preserve the technology that decades of accumulated knowledge (not to mention the essence of tone) would be lost forever.”
It can take up to a week to properly analyze a single transformer. Aside from the need to catalog and replicate these gems, we’ve tackled these projects for other important reasons. What makes a great-sounding transformer tick is no longer mysterious. Prior to our research the engineering community did not fully comprehend the characteristics of a good electric guitar amp transformer. We’ve used this hard-won knowledge to look beyond the confines of conventional engineering to find the previously undiscovered rules behind the most desired electric guitar amp tones.
VG: If a transformer dies will a replacement change my tone?
Sergio Hamernik: Until Mercury got involved if your transformer tanked there was a good chance that your sound would be lost forever. An amp tech could spend a lifetime fiddling around with caps, resistors and tubes and never find your sound again. The missing component in the equation was the transformers.
Oddly enough, duplicating build quality so that each and every transformer of a particular model, or period, sounds exactly the same had been a struggle in the past. Traditional manufacturing methods have always produced inconsistent-sounding transformers. Literally no two had the same sound. This only makes sense when you realize that few were aware of the transformer connection with tone. This also explains why the average amp tech uses random and generic transformers. They just didn’t know any better. The ability to buy an identical replacement transformer, or an upgrade for that matter, is a major breakthrough in amp tone — there’s no doubt about it.
There’s also a side benefit to consistent build quality that some players and amp techs are just beginning to discover. Mercury catalogs many design variations for all the popular amps. This means that you can easily and reliably experiment with the tone-enhancing qualities of other transformer designs and amp configurations.
VG: Why are transformer magnetics so vital to guitar amp sound?
Sergio Hamernik: Once you understand that generic “by the book” transformers can actually neuter your tone — the battle is over. Your choice in transformers opens the door to MAJOR tonal possibilities.
When you listen to all the different tube amps made over the years, it’s brutally obvious that the really bad-sounding variations had junky transformers (even though they were usually within design spec). We know this because when you simply replace the stock transformers with quality units they come alive.
There’s a curious phenomena associated with cheap magnetics — they tend to make an amp fatiguing to the ear — uninspiring to play or listen to. Boring, actually. With tonally dull transformers you just can’t get the other components to sound as they should. And the fun doesn’t stop there—inferior transformers result in amps that are unreliable, have a tendency to overheat, etc. You can easily identify them by their uninteresting, thin-sounding and harmonically anemic tone. Unless one is stone deaf, the sonic superiority of quality magnetics is obvious.
“Once you understand that ‘by the book’ transformers can actually neuter your tone — the battle is over.”
It’s important to understand that the pioneers of the electric guitar amplifier and most of the techs that followed were self-taught. It only makes sense that much of what they came up with were results from happy accidents. But despite their trial-and-error methods with tubes, speakers, and other components, many of them misunderstood the role of the amp’s magnetics (transformers) as it relates to electric guitar tone.
Over the years there’s been an overwhelming number of hit-n-miss transformer designs used in guitar amps — even within specific models. Mercury has had the benefit of the rear-view-mirror, looking back over time, discovering what sounded great and what didn’t.
Mercury’s holistic approach has taught us that the unique nature of the amplifier seldom lends itself to just one ideal set of transformers. Can you imagine that for the Bassman sound alone Mercury inventories over 2,000 transformer combinations? The differences may be slight, but we cover just about every conceivable tonal and configuration variation for that model amp — factory, mod or custom built. And that’s just one amp line out of hundreds — Mercury’s growing library is approaching every amp ever made (including the odd-balls!), from 1948 to 2006!
Our current library consists of hundreds of unique transformer designs and their variants. Aside from vintage, we also have our enhanced next-generation Axiom designs. They incorporate many of the discoveries we’ve developed for even better-sounding, more inspirational amps.
VG: I understand Mercury has three separate electric guitar amp transformer lines?
Sergio Hamernik: Everything we do has evolved from the real needs, wants and requests of our user base. Mercury’s products are all logical extensions of each other, but there are actually four separate offerings.
Mercury Vintage — our one-off service where we repair or restore otherwise valuable, usually vintage transformers. There are no modifications or enhancements added. These one-off restorations are ordered by players who are aware that their original (and valuable!) transformers are expiring but want to continue using the amp because they love its tone.
ToneClones are tonal duplicates of best-of-breed vintage amps. We have hundreds of designs and every one of them is from a stellar-sounding original. Indeed, it was our customers who helped to invent the ToneClone line. If you want to make your vintage-style amp sound as close as possible to the best-sounding amp of a specific period — you need to hear our ToneClone series transformers.
The Axiom series is a totally new concept in tube-based amp transformer design. They marry the best of the vintage-era and Mercury’s breakthrough discoveries. Axiom-ized amps give you more tonal “bloom” — vintage-sounding but more, a lot more. There’s a growing group of boutique amp builders, as well as tech-savvy players, that have been working with them. Of all the raves and testimonials we receive daily, the most emotional are those by our Axiom users. I’m particularly proud of the Axiom series because we believe they represent the future of tube-based amp designs.
And finally, custom transformer designs. Non-disclosure agreements prevent us from discussing our clients, but there are quite a few boutique as well as major brand manufactured amps out there with our custom designs in them.
“Think of what we’re doing as transformer archeology — not unlike opening ancient scrolls for the first time. Over the years we’ve unearthed some real treasures!“
All of our products are built like no other transformers in the world. We may be the only manufacturer who uses custom-formulated, American-made materials. Every single transformer is handmade, hand-tuned and tested by us before it leaves Mercury. Our proprietary processes and expertise are unique. We design and make every one of our transformers here in California — no work is farmed out to other countries.
VG: Where do we go from here?
Sergio Hamernik: Our work is fascinating, and as our advertising reflects, we’re having a good time doing it. But we wouldn’t have gone through all the drama of creating these exceptional-sounding transformers if it wasn’t for the support and encouragement we’ve received from so many brilliant artists and passionate players. Their passion has fueled our drive.
We view Mercury is a catalyst — reintroducing what inspirational, non-fatiguing real tone is all about. We’re also confident that we’ve also raised the bar for the “old” guys who long for the tone they grew up with. Can you imagine playing modern equipment that sounds even better than you remember it did back then? It was transformer and tube-based sound that originally turned the world onto electric guitar tone — the tonal qualities you feel more than just hear. At Mercury we believe that transformers are the last key to the tonal puzzle.
Source: https://mercurymagnetics.com/pages/news/VGmag/VGbuilderprof06.htm
With all of the money one can spend on an amplifier, be it boutique, reissue or just a good roadworthy unit there is one area that can be overlooked, the quality of the output transformer. It is essentially the final filter in your amp chassis from the tubes to the speaker, matching the two up so you can make music! Let’s talk with Sergio Hamernik and Paul Patronete of Mercury Magnetics™ to find out what we all need to know about this overlooked most integral part of getting the best overall tone from your rig.
MH: What services do you offer at Mercury Magnetics?
MM: We offer new hand-wound transformers and chokes. We also offer a rewinding service for vintage transformers. Mercury Magnetics™ can rewind a transformer back to its original specs. Founded in Southern California in 1954 and incorporated in 1968, Mercury Magnetics™ has built a solid reputation on superior quality, reliability and customer satisfaction.
Mercury Magnetics™ has the right combination of experience and a low overhead operation to meet specific requirements. Custom designs, quality assurance and safety standards are included as part of out total customer support with no-nonsense pricing that often beats out standard “off-the-shelf” components, while not being bound to their limitations. Mercury Magnetics™ has a long standing reputation for quality and reliability. These transformers are not built “offshore” or “south of the border,” they are 100% handmade in the USA and are backed by a money back tone satisfaction guarantee. Their line of Axiom® transformers are found in some of the finest and best-sounding modern production amps manufactured. We build transformers and maintain a high standard for tone in the tradition of our forefathers, making improvements that they would have made if they had access to today’s computer assisted designs and materials.
MH: To what degree of effort do you extend yourself when restoring a vintage transformer and how does it happen?
MM: We methodically unwind the vintage transformer by hand and document each wind detailing every anomaly and turn. We then rewind the transformer by hand so it will sound exactly as it did when it was brand new. The interior of the transformer is new and the exterior of the transformer is maintained so it will look like a vintage transformer and sound vintage as well. We attempt to use every piece of the original tranny that we can use. We DO NOT attempt to improve or alter the original tone or frequency response of the vintage transformer. Our rewinding service is more time consuming and can be more expensive than purchasing a new Axiom®transformer. However, with our attention to detail and experience the customer can be assured that their vintage transformer will look AND sound terrific! Professional musicians, technicians and studios regard our rewinding services as the best. For transformers, the core material suppliers’ industry sets a +/- 20% tolerance on characteristics like permeability to begin with, so most of the industry realizes that anything that’s an inductor or transformer has that kind of tolerance unless a particular manufacturer tightens the tolerance up. But when we were dealing with high speed stick winding methods of the ’50s and ’60s, they didn’t really have time to scrutinize each coil, because these coils were wound simultaneously. There could be six or ten coils being wound at the same time. For example, we’d find missing layers, or layers that had a different number of turns than what was specified. So what I did was blueprint a transformer, documenting every layer, the space between turns, the number of turns, type of wire, and in some cases oddball gauges and half sizes. I would also take measurements of dielectric constants, leakage reactance, and other characteristics to be able to clone a transformer. So we ended up providing a service where we would fully rewind and rebuild original vintage transformers. Imagine disassembling the laminations in a core, numbering each one and putting them back in the same sequence.
MH: Do you believe that an output transformer can decay and lose its tonality over time, and if so why?
MM: Absolutely. I’ve proven that point with some of my more cynical, high-end customers, and I did it in such a way that we took a Marshall JTM 45 or a Plexi, I forget which, but the amp had been in England for years and been brought over here. The owner thought that the tone had decayed over time, it seemed darker, lifeless, and the higher frequencies weren’t as pronounced. They removed the transformer, and all that I did was rebake it in an oven and drive out the moisture. We put the transformer back into the amp and it was pretty amazing; it became a lot brighter and more detailed from the upper midrange to the upper frequencies. I’m not recommending that anyone start baking their old transformers. What we do with our transformers to avoid that degradation process is use a resin process that hermetically seals the coils. We do it in a vacuum chamber in which the coils are impregnated with the resin material and then we bake it thoroughly. Because of this process, our transformers should way outlast older transformers, including those made today.
Transformers are still being made today with the same mindset, do it as cheaply as possible while offering the customer a decent value for the money. It’s correct for the required impedances and matches all of that, but the rest of the details have been omitted because they just don’t have the time and budget to do the longer process. Years of research led us to the conclusion that not every aspect of a vintage transformer needed to be copied. There were problems and limitations in their day, so why repeat them? We achieved better results by combining old and new technologies. Making the math work for the best tone characteristics together with improved consistency and longevity is the formula we chose to follow.
There are a lot of vintage amps today with transformers that are going bad simply because they have aged. The tonal quality of the amp is deteriorating along with the transformer. Paper and certain types of varnishes used in these transformers tend to have hygroscopic properties. Moisture is absorbed over time affecting the insulation system and increasing the chance for high voltage breakdowns. To make matters worse, the primary winding voltage is high enough to produce a corona effect whose ions help oxidize this insulation. Over time, reliability and tonality will suffer. Do you believe in transformer cancer?
MH: In conclusion tell us what you think makes you the best company to work with.
MM: Our customer service is second to none! Paul Patronete heads the Axiom® division. He is an accomplished guitarist and has an experienced ear for vintage tone. Paul is more than happy to help our customers find the exact transformer to fit their tonal needs. Our website is constantly being updated with vintage and modern transformer versions. We will probably always be 2 or 3 pages short of having all of the various models listed that people may be interested in. Of course, we can’t possibly list every one-off we’ve done. We offer modern, updated versions of many of the classic transformers. We have added impedance taps for many of the classic Fender transformers, which were never originally offered. Having a detailed transformer spec is only the beginning. Breaking down into fine details what materials and assembly techniques were used decades ago help us assure our customers an accurate reproduction of vintage tone. We have carefully selected the best of new and old technology to put performance and quality ahead of economy. Our transformers are hand wound and the cores are hand stacked. Some materials we fabricate in house and others, like our steel laminations, are custom ordered. Because we build them one at a time, Axiom® Mercury Vintage™ are only available in limited quantities.
There is an audible difference between a budget transformer and an Axiom® Mercury Vintage™!
A good output transformer should go beyond its job of impedance matching. An amplifier’s overall personality depends on it. A desirable output transformer’s distortion has more detail; the harmonics seem even and smooth. Played clean, the transformer should sound natural without harshness. Obviously within the boundaries of the authentic tone characteristic the player is seeking. Better said, we still can’t make an apple into an orange. The output transformer is pretty much the last tone filter in a series of components. Other factors like tube quality and speakers can play an important roll as well. Also if you were to look at an amplifier circuit as a modulated power supply, then the quality of a power transformer and choke, if a choke is used in the circuit, it also affects tonality. The ghost note phenomenon would be an example.
A lot of the people modifying Marshall amps don’t want their transformer to break up so easily when they really overdrive their amps, and they can have a custom transformer built that will handle gobs of gain and still hold it together. A boutique amp builder might come along and specify a particular classic transformer with a few improvements. It’s all passion, really, because this is not by nature a high-dollar, profitable business. In fact, the machines that we use to hand wind the Axiom® transformers are from the 1960s.
In the early ’80s there were dozens of companies doing what we do in this area, and now there are perhaps 3 or 4. It’s frustrating for most transformer makers to have a musician describe to them a desirable tonal characteristic when that can’t really be put on paper. You have to at least be able to see things from a musician’s perspective. Paul and I have a decent guitar and amp collection, and we try to stay abreast of what’s going on. And we also have a lot of walk-ins and a sound room, so people can bring their amps in and play and talk about what they want.
Most of the current transformer manufactures sell them cheap and dirty, their approach is cookie cutter, they offer an okay value for what you get, but they mainly use bottom of the barrel materials. Unfortunately, they are barely in the ballpark of what really needs to be done if someone is serious about getting a vintage tone. If you have an inductance bridge, a simple test is to measure the primary inductance on a vintage unit and then on a new transformer. You’ll find that the inductance on the new unit is usually less than half of the vintage transformer. There is no way that transformer can sound like the original, but if you aren’t interested in achieving the authentic sound of the past, then everything that’s out there today is all right. The devil is in the details, and there is no substitute for doing things by hand. Certain items for our transformers that I couldn’t source elsewhere, I learned to make here, because there just weren’t any other sources for them.
As you can see the people at Mercury Magnetics™ go to great lengths to make their transformers sound good and “correct,” not overbuilding them to prove a point. To get that tone back into your amp have your favorite repair shop get you a custom-wound output transformer from Mercury Magnetics™. We have only skimmed the surface here in this profile; the power transformer also makes a difference in the performance of your amplifier. Mercury Magnetics™also makes transformers and chokes which we will speak with Paul and Sergio about in the future. Until then check out their website at www.MercuryMagnetics.com and never stop learning about your tone!
Something very cool is happening the basement of Mr. Music, Boston’s favorite family-owned music store in Allston, Massachusetts.
After a lifetime of gigging, amp repair, studio building, and tone tweaking for stars like Joe Perry of Aerosmith, master technician Rob Lohr is building some of the finest boutique tone monsters to come along in a while.
I have always been impressed with anything I heard that was built in his shop, located in the basement of Mr. Music. Rob is a person of great detail. A technical question put forward to Rob usually yields a tutorial on the workings of electrons with respect to our favorite instrument, the guitar. Through the years, Rob and I have had many conversations about what a practical amp should sound and look like. A veteran of the gig scene himself, Rob understands what the working artist needs. In my world, 50 percent of the reason why something sounds good is because it does not need a crew of roadies to transport it, set it up, and break it down. These days, as indie artists, even for high-profile shows in theatres, we usually show up with our own favorite rig. It had better be light and tone-worthy!
When I heard Rob’s Dumbalina, an amp inspired by the legendary Alexander Dumble’s Overdrive Special, I was instantly hooked. Here was an amp the size of a Fender Princeton Reverb that was a very high quality, point to point, hand-made tone machine that had a kick like amps twice its size. Rob Lohr had somehow managed to pack all of the essential features of the best Dumble-inspired amps into a space the size of a Fender Princeton Reverb. He did this with no sacrifice in power (45w) and the highest quality components!
There are many other great D-Style amps whose components are a cut below Dumbalina’s. Yet Rob charges a modest $1800.00 for the basic amp, with additional costs for any custom work. Okay, yes, I did have to pay extra for him to add my name to the front in vinyl lettering with Fender-style script. Don’t be confused though, this is not the “Thaddeus” amp!
With a switchable 4, 8, 16 ohm extension speaker output, the amp offered everything you might need to grow your rig. Small gig: use the onboard 12-inch G12-T75 and walk in with the amp in your right hand and guitar in the left. Large gig: take an extension cab and utilize all of the 45 available watts to rock the stage with two or more 12-inch speakers.
The footswitchable Overdrive channel sounded like the mating of a Dumble Overdrive Special and a Two Rock Custom Reverb Signature. Overdrive that sings without over-saturation and responds to tonal tweaks on your guitar or subtle finger ornaments. The quality of OD of this amp, I will testify, is simply one of the best I have played. The clean channel can be crystal, but if you push it, you can get a singe on the top notes and a roar on the power chords.
The +4 effects loop provides you with the opportunity to use the highest studio grade effects in the loop. Aside from being whisper quiet, plugging in a high-end effect processor seems to lend a three-dimensional quality to the amp that makes it sound much bigger than its physical proportions might suggest. Of course, you can use a dumble-ator or clone thereof to use line level floor pedals, but why not use some of the high-quality studio grade pedals that are coming out these days? TC Electronics makes a couple and so does Eventide. More and more pedal manufacturers are giving you the option of the studio level +4 signal, ready to plug into your D-style effect loop. (See previous post on Effects Loops).
The three switches that you normally find on D-clones for Bright, Mid, and Bass are neatly hidden in Dumbalina: Each tone knob (Bass, Treble, Mid) has a hidden, whisper quiet, pop-less pull-boost feature which takes the whole thing up to a different kind of 11 heaven. The Volume knob has a presence boost. When the Tone Bypass is engaged (often called Pre-Amp Bypass or PAB in other Dumbl- inspired amps) the treble pull pot doubles as a bass boost. The result is the most useful “PAB” option that I have ever seen with a corresponding increase in low end that makes this feature a very practical and useful option for me. Usually I shy away from PAB because it might sound a little gnarly, or less friendly in lower volume settings, even though it works wonders for cutting through in the heat of the mix at high volumes.
My most recent gig was a power trio gig, a Hendrix tribute concert. I used Dumbalina’s overdrive channel for the solos that were not over-the-top, so to speak. When the band started really bashing, I could get away with using my Tone Bypass to cut through the mix. Really very flexible tones on this puppy! The 45w is just what you need to sing at lower volumes. Push the envelope a bit and you get great power amp overdrive without scaring the non-guitarists out of the room. In addition, there is a master volume/loop send level that allows you to get the tones you are using at lower volumes without changing the character of the settings. A well thought out amp for the working musician. At 34 pounds, the amp is welcome at any gig that I play!
In the studio, Dumbalina reigns supreme. I have just completed tracks for a tribute cd. R&B versions of Jimi Hendrix tunes. I used Dumbalina for many of the guitar solos and rhythm tracks and, well, tune in next year in the Spring to hear what I think are pretty amazing guitar tones.
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Rob builds every aspect of the amp. From the cabinet and grillcloth to the faceplate (painting and vinyl lettering)
the meticulously wired components inside this amazing amp.
Current wait time is only something like three months, since Rob is building each one by himself. I am sure as the word gets out, that list will grow and grow. It will still be worth the wait, I promise!
Here is the icing on the cake: roughly six months or so after you get the amp, after the amp has been broken in. Rob will sit there with you and do the final tweaking of the components WHILE YOU ARE IN THE SHOP! He will look at the levels and settings that you choose and tweak the internal components so that a great amp becomes an even greater amp, tuned to YOUR signature style of playing. This is an amazing benefit and it is the feature that pushes Rob to the front line of amp builders. (Isn’t that why Dumbles became so popular and expensive? Alexander Dumble would tweak them to the playing style of the owners). Rob recently spent 10 hours—yes folks, 10 hours in the basement at Mr. Music—tweaking an amp for client Alex Potts, so he could have it ready for his move to LA. In my Berklee Online course, Funk/Rock and R&B Soloing, I talk about signature tone. Folks like Robben Ford, who within a couple of notes, announce their presence on the recording whether or not you are even close enough to read the album credits. I believe that this amp can open a door to this concept, and with the post-build tweak, you just might be creating some new history.
Here is the latest version of Dumbalina that Rob is completing, with a couple of new tweaks and slightly different cosmetics on the faceplate, which include corresponding faceplate lights for the lighted footswitchable Overdrive and Tone Bypass features: Sweeeeeeet!!
Here is the scoop on Dumbalina, from the hand of the builder himself, Rob Lohr:
CABINET-The cabinet is Grade “A” pine joined with machine cut half blind dovetail joints and internally braced with poplar. I will cover the cabinet with any available tolex and grille cloth, and you have your choice of appropriate loudspeaker*. The standard faceplate is brushed aluminum with black letters, but I can do colors for a small upcharge and you have your choice of knobs**. The handle is a good quality faux leather that comes in brown, black, or blue, and I use 1″x2″ heavy duty rubber feet and stainless steel cabinet corners and hardware.
*speaker must be of appropriate power handling.
**knobs must fit 1/4″ shaft and comply with existing chassis hole spacing.
CHASSIS– The chassis is steel with welded joints and all hardware is stainless steel. The transformers are MERCURY MAGNETICS FBFVL-P 120v power transformer, FC-VIBROL choke and FBFVLR-OS Fatstack output transformer(4,8,16 ohm selectable). I can do selectable AC input for a small upcharge. The tube compliment is: 2x 12ax-7(pre), 1x 6sl7(PI) 2x 6L6GE(output) and a GZ34(rectifier). I use Belton tube sockets and retainers. I use a combination of Alpha, Clarostat, and Bourns potentiometers, Cliff and Switchcraft jacks, plugs and switches. All shielded leads are Mogami console cable. All unshielded signal leads are teflon coated solid copper core silver clad. All power supply wiring is PVC jacketed stranded copper.
ELECTRONICS– 100 percent hand-wired point to point construction. Hand made 1/8-inch fiberglass turret board, a combination of Metal oxide, metal film and carbon composition resistors, Oil and foil signal capacitors, and high quality electrolytics. There are some other solid state components, but they are related to the switching circuits and are not in the audio path.
LIMITED LIFETIME WARRANTY– I don’t warranty speakers, tubes, or output transformers for obvious reasons …but if anything else ever breaks I will fix it for free for ever and ever. Or until I die, which ever comes first.
Here is the bullet list of Dumbalina Specs:
Output power———–45 watts
Tube compliment——–2x 6L6GE, 2x 12AX-7, 1x 6SL7, 1x GZ34
Output Impedance——4,8,16 ohm selectable
Effects loop———— post pre/ pre power half normalled break out with send level.
Foot switches———-Over-drive and tone bypass(PAB). Both can also be controlled by front panel switches and are indicated with both front panel and foot switch mounted LED’s. The footswitch over-rides the front panel switches.
Controls—————-Volume, Treble, Middle, Bass, Overdrive, Level (ratio), send level.
Pull Pots:
Pull Volume————-Bright
Pull Treble————–Hi mid boost
Pull Mid—————–Lo mid boost
Pull Bass—————-Bass boost
Speaker Celestion G12T75, 8 Ohm
Rob Lohr can be reached at Mr Music in Allston Massachusetts at 617-783-1609 or at robmadoak@hotmail.com
Here are few demo videos that I just did:
OVERVIEW:
Of course, the perfect segue would now be to decipher the “special” nature of the original output transformer in Neil Young’s narrow panel tweed Deluxe, providing you with a timeline in which these happy accidents appeared, or better yet, a source for clones of thee special gems via, say, Mercury Magnetics. Sorry… we asked, and while the guys at Mercury had heard the same story about the output transformer in Neil’s Deluxe, we can’t offer any definitive clues to what Larry described as “the most perfect way form.” However, we can immodestly suggest that you snag a TQ Clarksdale [ed. note: built using custom Mercury Magnetics trannys]—a faithful clone of our original 1959 DeArmond 1×12. It’s Neil’s amp in spades and he doesn’t even know it. The first batch of ten have been shipped and a gutsier, louder or more soulful 20 watt 1×12 has never been built. We can’t (and don’t) take credit for the original design—that belongs to an unknown engineer at Rowe Industries in Toledo, Ohio circa 1959—but we can state without any doubt whatsoever that the Clarksdale nails the tone and attitude of the original, and the original is the most impressive 1×12 we have ever heard. It’s got more bottom end and stronger mids than a tweed Deluxe, and where a Deluxe folds up, the Clarksdale roars all the way to “10.” Ain’t no quit in the Clarksdale, and like Neil Young’s Deluxe, a lot of the mojo is found in the DeArmond’s mammoth, original output transformer.
With Young’s legendary tweed Deluxe off the board, we chose to put the vintage Vox AC50 Larry provided for Frank “Pancho” Sampedro on the Ragged Glory tour and recording sessions in play. Now, for those of you who tend to shy away from the potential complications that 40 year-old amps can present, the tale that follows will not inspire confidence, even though in the end, we did reach the promised land.
We found a 1965 gray panel Vox AC50on eBay with a “best offer” option. A search of previously completed auctions revealed that vintage AC50shad recently sold for anywhere from $900 to $1600 (more for the earliest, small box candy panel models with tube rectifiers). Since Larry’s “Pancho Vox” was a mid ’60sgray panel with silicone diode rectifiers, we made an offer of $950 for the ’65, which the seller accepted.So far so good. When the amp arrived from Florida,however, we immediately noticed that the chassis had dropped inside the cabinet. Vintage JMI Vox chassis are mounted on a plywood shelf that allows the amp to slide in and out of the cabinet, and due to the seller’s pathetic packaging job, the plywood board in the AC50had splintered and cracked beneath the weight of the chassis. The shelf was shot, but since a cursory fire-up led us to believe the amp was in good working condition as advertised, we asked for and received a $100 credit and cut a new plywood shelf for the AC50from a reproduction AC30 cabinet we had used to house a vintage ’63 AC30head. Piece of cake, and a very quick and proper fix.
In the interest of authenticity, we also ordered a 4×12 cabinet loaded with aged Celestion G12H30s (Hellatones) from Avatar Speakers. They were running a clearance sale on loaded 4x12s for just $378 and $49 shipping, so we bit, and people, this cabinet kicks the living shit out of our vintage Marshall 4×12.
With the cabinet delivered, we were anxious to uncork the AC50at full roar, and we did—for maybe five minutes. The thick sound of the Vox filled the room, the house and the block with a gorgeous,incendiary bloom through the Avatar cab and our blacktop Les Paul, until the joyous noise was suddenly contaminated with a most noxious and fear-some popping, fizzing and spitting, while we sighted a glowing red spot on the plates in one of the Svetlana EL34s. Not good. Off to Bakos Ampworks….
After an hour of probing on the bench, Jeff asked,“Do you smell that? Man, I think the output transformer is smoked. It’s probably been going out for a while.” Jeff patched in a substitute which eliminated the crackle-spit and confirmed, “It’s toast.” We immediately punched the number for Mercury Magnetics, and with our print deadline looming large, we had the Vox tranny shipped 3-day UPS from California. Jeff popped in the Mercury ToneClone tranny and replaced the original silicon diodes with FREDS. We also A/B’d an older pair of original “Winged C”Svetlana EL34s with a matched pair of NOS TeslaEL34s acquired from KCA NOS Tubes. At $80/pair,the Tesla’s are reportedly comparable to NOS Mullard sat more than three times the price. We also installed two lightly used Mullard ECC83sin the Normal channel and a spare NOS RCA 7025andNOS Teslain the Brilliant channel. But we were still missing an essential ingredient in the “Pancho” rig….
With the Vox AC50 brought back from the brink and the ’57 Junior found, we were finally poised to experi-ence Ragged Glory. We prudently set the volume controls for both channels of the Voxon “7,” following Larry’s recommendations for tone controls—treble dimed and the bass low. We’d ease into “10” on the volume controls later…. With a flick of the toggled tripwire the Vox lit up, and within 10 seconds the P90 was humming through the four Hellatones. We stepped back a few feet, brought the volume control on the Junior all the way up, turned away from the four twelves and cut loose with a tight, slashing chord progression out of E major. Digging deep into the Junior, the Vox responded as the twin EL34s became fully inflamed, gorging on 430 volts. The tone was thick, complex and gloriously ragged with a clarity, punch and trebly character that masked nothing—the perfect burning, churning, flannel and leather rhythm tone. Hit the low E string on a fat E major and it holds…. Come over the top with an upstroke on the E and B strings and the Vox responds with a gorgeous, penetrating cymbal splash that hangs as long as you wish. Need a dash more mids? Dial back the tone poton the Junior, Pow! There it is. Thanks to the FREDS, the entire rig breathes with an extraordinary touch sensitive feel, and even on “7” the Junior could easily be coaxed into howling cries of polyphonic feedback. After 15 minutes, we reached over and dimed both volume controls…. Now we were welding some very serious shit—Mississippi Queen meets Powder finger…. And this was 50 watts of classic, vintage Voxtone, mind you…. Harmonically richer, better endowed and far less linear and one-dimensional than a vintage Marshall—a cross-bred beast with a level of gain, distortion and raw heat far beyond the capabilities of any other vintage British amp unaided by a pedal. The tone, the vibe, the drama of this amp is stunning, and it left us wondering why the vintageAC50 gets so little respect. We can think of no other vintage or current production amps that do what the Vox does. Not one. Of course, your results could vary, so here are a few tips for you brave souls willing to take the plunge.
Don’t be fooled into thinking that the Voxis solely a“rock” amp. Kid Ramos blew us away at a blues gig playing an AC30with a Fender reverb box, and his was one of the best blues tones we’ve ever heard anywhere. Expect the same from an AC30.
Do not fear replaced transformers. You’ll pay less for the amp and the ToneClone replacements from Mercury Magnetics will outperform many tired originals.
Expect the unexpected and coolly deal with it. Voxamps aren’t Fenders—things like speed nuts on the chassis for the cabinet mounting screws are often missing or broken, but they can easily be replaced.Good tubes are also essential, but not every brand will provide reliable performance or the best tone in aVox. You must also exercise extraordinary caution around the AC50when handling the chassis outside the cabinet—even when performing simple tube swaps. The preamp tubes are mounted directly above two uncovered filter caps that remain hot even when the amp is unplugged. One slip and your Quest for Tone could be over.
Plan on investing in a thorough checkup by an experienced amp tech who can deal with cold solder joints, degraded components, old filter caps and proper biasing, before your amp takes a dump. Recommended amp techs follow, along with contact info for Mercury Magnetics.
Anyone familiar with Mojave Ampworks founder Victor Mason’s other venture — a California dealership of vintage British amplifiers known as the Plexi Palace — will be aware of this amp maker’s fanaticism for classic Marshall-style tones. The Scorpion outwardly appears to take a serious stab at satiating that craving in a modern package, but don’t be too quick to label this 50-watter as simply a Marshall plexi update. While the Scorpion certainly aims squarely at the big Brit-rock tones of the late 1960s and early ’70s, it’s nowhere near to being a clone, and the design has enough clever twists to make it an entirely original creation. Although nominally a 50-watter, the Scorpion aims to provide big-box 100-watt sound and feel in a small package.
The core of the Scorpion’s sonic DNA revolves around that big, crunchy, dynamic EL34 sound with the characteristically thumping lows and singing highs. But this model redraws the roadmap that takes you there, and adds plenty of new ingredients in the name of versatility. Mojave keeps the adjustable fixed-bias output stage with a dash of negative feedback, cathode-follower tone stack, and solid-state rectification that partly define the post-1967 Marshall 50-watters, but re-labels the tone stack as Bass, Low Mid, High Mid, and Treble, with High Mid taking the job of a Presence control. It also employs a nifty trick in the preamp stage that has become something of a Mojave standard: internally ganging together two different first gain stages comprised of an independent, parallel-wired twin-triode 12AX7 for each—one voiced to emphasize bass, the other to emphasize treble—and providing a Volume control for each so you can blend them together. This is not a master volume amp, but it carries a Power Dampening control on the back panel that governs a unique proprietary circuit that reins in volume levels at the output stage, allowing you to take the Scorpion from 50 watts down to 3 watts, and anywhere in between. Other features include High and Low Sensitivity inputs, and a back panel 1/4″ Line Out jack with a Level control and ground lift alongside dual 8- and single 16-ž outputs.
As alluring as it might be from the outside, much of the Scorpion’s appeal reveals itself when you pull the chassis from the cab. This amp is hand built to some of the most exacting standards found in the market today.
Powder-coated black metal grilles protect components front and back, and the brand is boldly represented by an acid-etched aluminum nameplate. The rugged turret board follows a linear layout from input to output stage, and the flying-lead connections to transformers, potentiometers, switches, and tube sockets (all chassis mounted) are made with Teflon-insulated, silver-plated copper wire. While many amp makers swear by old-style carbon comp resistors for “warmth” and “vintage authenticity,” Mojave uses high-grade metal film resistors because they can be obtained in more precise values, and generally result in a lower noise floor. These share the board with Sprague filter capacitors and custom-made, one-percent tolerance film and foil polypropylene signal capacitors. Transformers are all custom made for Mojave by the highly regarded Mercury Magnetics company, and the whole shebang is bolted together in a reinforced aluminum chassis. Finally, the output transformer presents a novel twist on the classic 50-watter formula, as Mojave has spec’d it for “triple-capacity,” which can handle as much as three times the Scorpion’s 50-watt output. This approach can achieve the response of a 100-watt stack in a smaller amp, resulting in firmer lows and remarkable headroom.
Our review sample came with the 2×12 semi-open-back cab loaded with Celestion G12H-30s, but a closed-back 4×12 is also available for $985 retail. The cabinet is a robust, yet portable unit with a single, recessed handle positioned top center.
I tested the Scorpion with a range of guitars, including a Fender Stratocaster and a Telecaster, a Gibson SG Special, and a PRS Singlecut Trem. The overriding impression this amp left with me was one of power, body, and massive volume — even with single-coil pickups. This is one massive sounding amplifier, and Mojave has certainly achieved the goal of attaining 100-watt-style performance in a 50-watt package. It delivers a wide, blooming soundstage with tight, but not overly booming lows, a thumping midrange, and glittery, yet nicely recessed highs. In short, you get broad, punchy, in-your-face dynamics across a frequency spectrum that’s very flattering to rock guitar.
With the Strat and Tele, the Scorpion exhibited stunning clarity and superior headroom up to about a ten o’clock position of the Volume controls, at which point it was already too loud for home studios, basement rehearsals, and many club gigs. Humbuckers and P90s brought out the raunch a little sooner. Roll it up from there, and you segue through toothsome crunch to absolutely screaming lead tones — both of which are easily cleaned up at the guitar’s Volume control. This is the fat, tactile, airy, classic sound that arena-rock dreams are made of, and when you get the volume up anywhere from one to five o’clock, it’s a rare and spine-chilling experience to just stand in front of this rig and wail. Tweak the EQ to taste, put a booster or distortion pedal in front of it as desired (all of which this amp handles very well), and there’s very little in the broad fields of rock, blues-rock and metal that it can’t do.
That said, the trend these days is toward downsizing, and plenty of players are looking for amps that sound like cranked 50-watters in 15-watt packages, not 50-watters that sound like a 100-watters. The Scorpion’s Power Dampening control is a cool feature that brings levels down as much as you’d like, but it does color the tone a little bit, and you also need to dial down the Volume controls to retain similar headroom at lower volumes. In short, this powerful monster is most cut out for serious rockers who expect to put in most of their playing hours on large stages.
The Scorpion also sounded fantastic through the 2×12 cabinet, which seemed to take everything I could throw at it without breaking a sweat. But if you plan to play this amp toward max in big venues, you might consider pairing it with Mojave’s 4×12 cab. I ran the Scorpion through a custom 4×12 with G12H-30s in my rehearsal space, and it proved an equally thrilling endeavor, with that huge kick in the gut that lets you know you’re pushing a lot of air. However, it wasn’t demonstrably louder than Mojave‘s very efficient, compact open-back 2×12, so the choice is yours. But whatever you blast it through, this is an extremely accomplished-sounding, as well as a stunning piece of craftsmanship.
Source: https://mercurymagnetics.com/pages/news/GuitarPlayer/GPAug07.htm
A couple of months ago, I checked in a pile of amps for repair/freshening up for a band that was going into the studio to record another album. While reviewing this pile, I found that I was in possession of the main recording amp for the front man. It was a little vintage Supro that had certainly been around and through the ringer. While it definitely had a fantastic tone, it had noise and reliability issues due to its age. I decided to surprise the fellow and make a replica as close to the original as possible. In my own amp designs, I try to add a dash of originality into the mix, but for this project only a carbon copy would do. I pondered the project endlessly, obsessing on the creation morning, noon and night. A couple of days after deciding on a game plan, I received a call from the band’s liaison asking me if I would mind making a clone of that amp only with less noise and increased reliability. I was now on the hook. Time to put my plan into action.
The first step was to try and find a schematic for the little Supro Super. A few were found in my files and on the internet, but they didn’t seem to be of this exact incarnation. Since my plan was to be blueprinting and cloning this amp anyway, I decided to dig in and make a schematic. I traced the circuit, noting the apparent values (what was written on them) of resistors and caps etc, as well as the type (composition) along the way. All of the resistors were carbon comp, and the coupling caps were mostly ceramic discs. I then traced the circuit again, this time measuring and taking notes on the actual values and voltages of the resistors, caps, transformers, plate voltages, cathode voltages, etc. The differences were substantial. The tolerances on these amps were fairly broad to begin with; on top of that, the values of the components would certainly drift over the 40 odd years since this amp was built regardless. Now that I had the blueprint made, I needed to acquire the parts.
I placed a call to Paul Patronete of Mercury Magnetics to get transformers with the exact specs required. We do quite a bit of business together and he has always been a great help with projects like this (as well as with my DB7 trannys). Surprisingly, they had them on the shelf and ready to ship.
With those on the way, it was time to start punching the chassis. I selected an aluminum box to be used as a blank and laid out the measurements. My goal was to create a replica in tone and feel only, so I took the liberty of moving some of the component placement to cut down on the noise. For example, I spaced the transformers out a bit and took into consideration the proximity of the output tranny and the first gain stage. During the construction, I also implemented star grounding and ran shielded wire. For the resistors I used NOS carbon comp where it made sense tonally (input, plate load etc.) and a mix of carbon film and metal film in other places. At times, I had to create values using two resistors to try to match the values of the ones that had drifted.
Ok, ok, I know that I said that I was making a carbon copy clone here but I just couldn’t bring myself to use ceramic discs for the coupling caps. Instead, I used caps that we have made to our specs for our amps by a high-end manufacturer here in the U.S. They don’t have the same two-dimensional graininess as the ceramics. Instead they have a very open and airy quality to them but shift to the point of flattening out a bit when using some right hand dynamics.
With the guts assembled and all of the voltages checking out, it was now time for the speaker selection and cabinet construction. I chose to make a separate baby head and speaker cab for this project. I used pine for its tonal qualities and tried to match the size of the original combo. For the speaker itself I used an 8″ Weber VST Alnico that was a direct replacement of the original. The cabinets were then covered in a very funky black cowboy print type Tolex. Tube selection was also very important. I tried many tubes from my private stash and finally rested on an NOS RCA 6V6 for the output and NOS RCA grey plates for the preamp.
The end result was satisfactory but there was something missing. The tonal characteristics were all there but it just didn’t seem to have the “magic.” I gave it to the client and told him to play/abuse it a bit to see how the character would change when the amp/speaker had some time to break in and then I would finish the voicing. A couple of weeks later I picked it up from their studio along with a wish list of how the tone was to be sculpted. I placed the amp on my bench ready to start the voicing, plugged the head into a very weak and old 10″ Alnico Jensen that I use as one of my test speakers and strummed a chord. WOW! It sounded amazing! Hmmm, what happened I wondered?
I then plugged the amp into the cab that I had made for it. While it still had the tone, the dynamics just weren’t there. The speaker that was in my test cab seemed to be the missing ingredient! Fortunately, it was one of four that I had pulled out of an old Hammond organ cab of mine. The new speaker cab was taken apart, a 10″ hole cut in the baffle board and one of the speakers installed with hardly any room to spare. I tried again… WOW! With this combination you could play perfectly clean, sparkling chords and using right hand dynamics shift into blistering, compressed distortion. Truly outstanding! The Weber is a fantastic speaker — don’t get me wrong — it’s just that for this application I needed a really tired, old, crummy speaker to do its thing. The end result far exceeded the greatest expectations of both my client and I. Certainly well worth the time spent on a small pet project in a busy shop. But hey, who needs sleep anyway?
Source: https://mercurymagnetics.com/pages/news/PremierGuitar/PremierG-16.htm
Many of you are already familiar with our resident amp tech, studio owner/engineer and advisory board member Jeff Bakos. In his spare time, Jeff occasionally builds amps for clients on request, and lately he’s been asked to build… you guessed it – small little biters. Since his personal GA-5 has been featured so often on various recording projects, Jeff toyed with the idea of recreating the Gibson GA-5 Skylark for a minute, but given the fact that vintage GA-5s remain fairly plentiful, he ultimately decided to design his own simple take on a smallish amp – the 8 Ball. Housed in a Mojo Champ cabinet, the 8 Ball is built with one of our favorite tens, the Eminence Legend Alnico 1058 (that’s a hint), Mercury Magnetics trannies and choke, and premium components, including Sozo coupling caps. With the bigger Mercury Princeton transformer set, the single 6V6 / 12AX7 / 5Y3 design is capable of producing 10 watts of power. Features include dual inputs, volume and tone controls, a front panel line out jack, and a “vintage” / ”modern” toggle switch also conveniently mounted on the front panel.
The “vintage” setting produces pristine Fendery clean tones up to 12 o’clock on the volume control, gradually followed by a progressively thicker growl with intense distortion and sustain. In this setting, the 8 Ball surpasses all the other small amps we’ve reviewed in terms of practical versatility with stronger, louder clean tones and a more gradual It’s back! We are now resuming limited production of our meticulous recreation of the original 1959 DeArmond R15 1×12 amp. You may recall that we initially produced a limited number of TQ Clarksdale amps in 2006, before our supplier for the original chassis informed us that small runs would no longer be possible. We’ve found a new supplier, and the TQ Clarksdale “DeArmonds” will be built again by Jeff Bakos with our original specs – pin cabinet construction and design identical to the original, original Mercury Magnetics Tone Clone transformer set cloned from our original ’59 DeArmond, hand-wired chassis, premium components including Sozo caps, Celestion G12H 70th Anniversary speaker, premium JJ and Tung-Sol tubes, Evidence Audio speaker cable, custom gold grill cloth and blonde Tolex covering. This 22 watt design represents one of the rarest and most toneful combos ever built. The original 1959 DeArmond 1x12s were built for just one year in Toledo, OH, and a clean example recently sold on eBay for $7000. In 2006 Jeff Bakos meticulously blue-printed our original DeArmond, Mojo created CAD drawings from the original cabinet design, and we sent the transformers to Mercury Magnetics to be cloned. The result is a phenomenal 1×12 that will generally kick any tweed Deluxe straight to the curb with a bigger, bolder voice and lush, musical distortion cranked. The 4-input, cathode-biased Clarksdale can be operated with dual 6V6s and 5Y3 rectifier for optimum burn, or a pair of 6L6s and 5AR4 for slightly more power and clean headroom. Blonde Tolex only, simply because it’s the coolest color…
You’re are of the phenomenon… Suddenly a guitar, amp or some other new or pre-historic gizmo seems to come out of nowhere to achieve white hot, must-have status. The same thing can happen with previously unknown builders, too. Take Marshall 18W “clones,” for example… For the past 3-4 years these recreations of the rare originals were hot, hot, hot, with small custom builders sprouting and thriving from within the 18W Discussion Page. This was good for builders, good for players, and an unanticipated consequence was spawned — the rapid expansion of the cottage industry providing small amp builders with custom-made chassis, capacitors, transformers, cabinets, and just in time, an expanded range of guitar speakers developed by Eminence and Celestion. By the time Marshall jumped into the game with their own hand-wired 18 and 20W amps, the custom-built 18W wave had begun to crest and break, but there is now a new ripple on the horizon that we predict will soon form a formidable new wave among custom builders — the Vox AC30. Granted, Korg has already issued their own limited edition version of a hand-wired AC30 following the success of the British-made Vox AC30 TBX reissue, and we have reviewed the AC30 Custom Classic in this issue with backup color provided by The Radiators’ Dave Malone. While the Custom Classic is a very affordable and perfectly respectable alternative, it would be unreasonable to expect an economically built, mass produced amp to seriously rival a vintage JMI AC30 in original condition that has been competently serviced by an experienced tech. What about the original Matchless DC30 built by Mark Sampson? Great amp, but not the same. Players craving the authentic sound of an original AC30 have four choices today—find an restore an old JMI, buy a reissue and play it as is, have the transformers, caps and resistors in the signal path of your reissue amp upgraded, or buy booteek.
Well, it’s one thing to lovingly resurrect the rather Spartan Marshall 18W circuit, and quite another to tackle the original JMI design, which is much more complex, costly and labor-intensive. Furthermore, some builders may succumb to the temptation to significantly “improve” the original AC30 circuit. That would be a mistake. The successful builder will locate a vintage AC30 with truly bitchin’ tone (assuming they are capable of identifying said bitchin’ tone) and build more, per the specs revealed by blueprinting the old one. As far as we know, this has yet to happen on a meaningful scale. To date, we have located one potential candidate built by DST Engineering that will be reviewed next month. If anyone reading this believes there are more, please let us know.
Meanwhile, let’s address the common belief that 45 year old Vox amps are too unreliable — dangerous, even — for ecstatic thrashing, let alone regular gigging. While it is true that the design of the AC30 (and AC50) provide precious little ventilation (the top vents are stingy at best), we have seen AC30s used by touring musicians and there were no flames shooting from the back (Daniel Lanois didn’t even bother with a backup). So we asked ace amp tech Don Butler (Toneman) to precisely describe the steps he takes to make a vintage Vox roadworthy…
Don Butler: Vintage AC-30s suffer a lot from neglect. People are under the misunderstanding that all you need to do to any vintage amp is replace valves/tubes occasionally, but it requires much more than that. Here’s what I do when I get an AC30 or AC50 in for service that hasn’t had anything done to it since the day it left JMI in Darford, Kent…
Replace the dual 16uf @ 500v can, replace the 32uf @450v cap in the supply line that goes from the bottom power amp section to the preamp, and replace the dual 8uf can in the pre-amp. Replace the 32uf @ 450v cap for the Top Boost circuit (if the amp has integral Top Boost). Replace all the 25uf @ 25v cathode bypass caps (I see a lot of Vox amps where all of the main filters have been replaced but not the cathode bypass caps. It’s really just as important to replace these as well, as they set the gain for each area of the circuit they’re in). While I’m at it… Electrolytic caps have a lifespan of 7 to 10 years. After 10 years they start to deteriorate and slowly affect the way your amp functions (and not for the better, either). If you have an amp that 35-45 years old with original filters in them, well then, you’re asking for a lot of problems by not changing them. I’ve had a few vintage amps where the filters were not changed and they eventually shorted, taking the output tranny or choke of the mains tranny with them. To me they’re cheap insurance to keep your amp working properly and sounding good. By the way, the worse thing anyone can do to any amp is not turn it on for at least an hour a month. That keeps the electrolyte in it’s liquid form and prevents it from drying out and crystallizing.
Back to JMI-land — replace the output section cathode bypass cap (250uf @25v) and the four 100 ohm resistors on each EL-84 socket. These almost always drift way out of tolerance. Use 1 2att 100 ohm carbon film. On any voltage path resistor that needs to be replaced, use a carbon film. But, in the signal path, never use anything but carbon comp, otherwise it won’t sound the same. Vox always used carbon comps for everything. These days you can get 5% tolerance carbon comp resistors — in the sixties you were lucky to et 10%, and most used + or – 20% resistors.
Check each resistor with a meter. If the resistor is more than 20% off, replace it. Check the output tranny. Measure the primary side from center tap to each anode. The center tap is always soldered onto the main supply filter can. Be sure to discharge the cans before you do this!! The anodes are hooked up to pin #7, and they should read very close to each other from the center tap to each anode. Each era had different readings. A Haddon output transformer has a different primary reading than a Woden and different from an Albion as well.
Clean each valve socket, input jack and pot with Caig DeOxit D-5 contact restorer. And here’s a bit that is as important as everything else — make sure every nut, bolt, screw and pot nut is tight. You would not believe how much you can improve the noise and hum in an AC30 simply by doing this. I’ve had amps where every one of them is loose! On the 12AX& that is used for the Normal and Brilliant channels., JMI used a wire from pins 4 & 5 to ground to keep the filament supply grounded. Cut this wire off from the pins to ground. Take two 100 ohm resistors and attach them from each side of the filament supply at the pilot lamp to ground. This is what Fender did for years to make the filament supply quiet. It’s an easy “center tap” for the 6V AC filament supply.
Check all your valves/tubes. Always use a matched set of EL-8rs and good 12ZX7s and a decent 12AU7. Spend the money for a good rectifier! You have to look at the cost of valves as an investment in your tone. Good preamp valves should last at least 10 years for NOS. I’ve seen many Ac30s with perfectly working Mullard GZ-34s that were 40+ years old. EL-84s get beat-up pretty good, but still important to buy quality valves. This is also important: With any and every JMI Vox Amp, use a Variac! Why? My wall voltage reads anywhere from 114v to 122v A.C. Vox amps want to see 105v to 110v MAX! The voltage selector may say 115v, but Sergio at Mercury Magnetics has told me many times that the real input voltage of old JMI amps was 110v max. If you plug your AC50 into the wall at 1222v, instead of your B- supply reading 470v like it should, you’ll get over 500v D.C. Most of the components are rated at 400v-500v max. By putting more in you run the risk of shortening the life of most of the components if not frying them outright. If you follow this advice and servicing recommendations and use a Variac, you should have a happy AC30 that will work for you for years without trouble. It doesn’t hurt every few months to tighten up all the screws, nuts, etc. If you tour or gig with an old AC30, you have to know at least a little bit about how to maintain your amp. If you’re too lazy to do that, then buy a new Custom classic and send it to me to mod into one that sounds very close to a JMI-era amp. There’s a good book you can get from a guy named Stephen Grosvenor in the U.K. called “A Service Engineer’s Guide to the Vox AC30 Valve Amplifier.” This just came out in June (’06).
TQR: Not all power tubes can take the heat that Vox amps produce. What are your favorite choices for output tubes in old AC30s and AC50s and do you have any suggestions for keeping these amps running at lower temps?
Don Butler: AC30s — Tungsrams and Polem/Telem (same manufacturer — these are made in Poland) for NOS and EI Elites for new tubes. The Tungsrams are very clear, open sounding with nice chime on the top end and a good tight bottom. Same with the Polems, but the Polems have a bit more midrange. I find Mullards very dark and flat by comparison. I’ve tried just about all the NOS EL-84 types in my Voxes and Marshall 1974X. The EI Elites are a great sounding tube but lack just a bit of the detail and harmonics of the NOS. Still, a great sounding tube compared to the rubbish that’s being made these days.
TQR: You’re known for upgrading stock “reissue” amps. Describe the typical upgrades and modifications you make to reissue AC30s and the most recent AC30 Custom Classic.
Don Butler: I replace the output tranny with a Mercury Magnetics clone, same with the choke, as the choke is a very important piece of the puzzle. I replace every resistor and cap in the signal path with carbon comp resistors and Sozo caps. I have an audio “break-in” CD that I run into the amps after I’m done. About 4-5 times simulates the amp having been played for around 80-100 hours. I do this because every output tranny takes around 20 hours to break in, and the Sozo caps take around 100 hours to break-in. This way when my customer gets their amp back it’s as if it’s already been played for a bit and should be more open and touch responsive than if it hadn’t been played. I do also play through them when I’m done. I have to make sure they sound right. I play them again after I run the CD through them, and it’s fun to hear the actual difference!
Source: https://mercurymagnetics.com/pages/news/ToneQuest/_2007/TQRJan07-1.htm
Let your ears re-discover and re-experience real vintage tone. Imagine having an unlimited budget (and time) to play thousands of amps — including the often spectacular specimens held in private collections all over the world. Then from this exhaustive search you get to pick the one or two that have THE sound.
ToneClone transformers are exact genetic duplicates from these sought-after amps. Many came from amps owned by your favorite players. The same amps that were used to record some of the greatest electric guitar songs we’ve known.
That’s why Mercury constantly seeks only the best-of-the-best transformers to add to our catalog. When an exceptional transformer is discovered, it is carefully studied, analyzed and duplicated. Mercury engineers clone every detail and nuance of these best-of-breed transformers — a process we’ve been refining and improving upon for decades.
ToneClone transformers are designed for upgrades, replacements or custom-built tube-based amps. ToneClone transformers come with both our 10-year Workmanship Warranty and Tonal Guarantee.
To find out more, or discuss to the characteristics of the different transformers sets available for your amps, give us a call or email.
I have a cool little 1980s Fender Super Champ. It’s one of the amp models that was designed by Paul Rivera. This little guy puts out about 18 watts through a single 10″ speaker. It also features Reverb and an overdrive mode. This is a great little amp to take to jams or recording sessions. It’s an all tube design and one of the last point to point hand-wired Fender amps. A few shortcomings of this amplifier are:
Two of the three shortcomings can be fixed pretty easily and for not too much money. The one that cannot be fixed is the footswitch circuit… I’ve tried and it’s just the design… oh well. First thing is to ditch the stock speaker and put in one that’s more efficient with more clarity and better bass response. I chose an Eminence Ragin Cajun and the amp totally came to life. You can do a gig with no problem once you install the Cajun.
If you want to take the amp up another level or two then you have to replace the puny output transformer. I removed the stock unit and replaced it with a Mercury Magnetics FBFDR-O model. This is the clone of the blackface Deluxe Reverb output transformer. It is definitely bigger and if you install in on a slight angle you can catch a mounting screw hole for a terminal strip so you do not have to drill any holes in the chassis.
The result is absolutely astounding!! It has been a long time since I upgraded a transformer in an amp and this swap reminded me how effective upgrading an output transformer can be. The whole amp just opened up and the bottom end got much tighter and defined… almost piano like. The overall volume of the amp increased and the dynamic range was broadened. There was much more harmonic content and overall the amp sounded and felt much more solid. Besides sounding and feeling better this amp was now a lot more gig worthy. A simple transformer swap did all that and only took about an hour from the time I dropped the chassis until I hit the first note. To me that’s a total home run!!
If you have an amp that sounds and feels good but want to take it up a level or two then let me suggest two reasonable upgrades: New speakers and a transformer swap… at least the output transformer. These two upgrades can transform your amp into something magical. Plus it is a lot less expensive than getting a whole new amp, not to mention the time you have to invest trying a bunch of them until you find one that works for you.
I am affiliated with both Eminence and Mercury Magnetics. If you have any questions and are interested in upgrades please email me and I can help make a recommendation or two on speakers and/or transformers. You will be amazed… I am every time!!
