Axiom series transformers are in a class by themselves. We’ve taken our advanced knowledge of modern transformer designs and mated it with our unparalleled expertise with vintage gear. The result is next-generation transformers that’ll blow your mind!

With Axiom transformers you not only get vintage tone — but a lot more! More bloom, more overtone color, and awesome tonal depth. If you ever needed a demonstration as to how outstanding transformers will affect your sound — Axiom transformers will astonish you.

Axiom transformers represent the most significant improvement in transformer design since the post-WWII era (American and British). Many mistakenly believe that modern transformers cannot duplicate the sound and tonal qualities of their original counterparts. Typically this would be true, however, Mercury has gone to extraordinary lengths to do the job the correct way. No other company has either the knowledge, expertise or the wherewithal to duplicate our efforts. Don’t be fooled by false claims.

The proof is in the product. Try our Axiom designs in your amp, and if you don’t love them, just send them back. No questions asked.

Axiom transformers come with both our 10-year Workmanship Warranty and Tonal Guarantee. Axiom transformers may be used for upgrades, replacements or custom tube-based guitar amp applications.

To find out more, or discuss to the characteristics of the different transformer sets available for your amps, give us a call or email.

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

Did you know that Mercury™ has been developing and perfecting THE next-generation of guitar amp magnetics? When it comes to guitar tone our Axiom® series may be one of the most significant advancements since the mid-1960s.

Here’s why. We now have the “rear-view-mirror” benefit of knowing what made certain amps sound good… and just as important — what didn’t. Mercury was the first, and still is the only company, to capture and retain the sound of the most desirable old school amps with our ToneClone® series trannys. But, along the way, we discovered that we could now do things the old school guys never dreamed of. The Axiom® series was born!

Our Axiom® series answers many of the “what if” questions that has plagued both players and amp designers for decades. For example: What if you could mix the characteristics of one amp’s outstanding magnetics with another — say, get both Fender– and Marshall-tones from the same amp without the lifelessness of digital emulation? Or, what if there was no quality limits imposed on how transformers were made (you wouldn’t believe how dumbed-down most transformers are!)?

The Axiom® series isn’t only the result of engineering expertise. We received profound contributions from many of the finest players who ever recorded—musicians who generously gave their insight and direction to this on-going project. Axiom® “high def” transformers take your tone, clean or distorted, to the next level. Axiom-ized amps give you more vivid harmonic overtones, added sparkle, more dynamic headroom, and much better note separation. Even if you’re into weapons of mass distortion, Axiom® transformers deliver a far wider spectrum of tonal variations and possibilities than any previous design.

So, whether you’re upgrading an existing amp, or working on a new design, give our Axiom® line a test drive—you won’t be disappointed.

Source: https://mercurymagnetics.com/pages/_misc/FAQ.htm#Next-Generation%20Trannys

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!

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It doesn’t take too much digging to find a laundry list of boutique amp builders using Mercury Magnetics transformers in their products. From Mojave Ampworks to Joe Morgan Amps to kits from MetroAmp, builders have found that Mercury knows their iron. While transformers rarely receive the same level of attention of NOS tubes, speakers, or even guitar cables, they are a major contributor to tone. Think about it—the power and output transformers are the start and end of the line with any amp.

Based in Chatsworth, California, Mercury Magnetics has been building transformers for close to 60 years. I recently had a chance to talk with Mercury’s Sergio Hamernik to dig deeper into their roots, find out what one can expect from upgrading their iron, and what sets Mercury apart. Prior to our conversation, I had the opportunity to witness the remarkable transformation of an Epiphone Valve Junior modified from stock to hot-rodded, using one of their transformer upgrade kits. Not only was it a noticeable upgrade, it was a revelation in just how important the role of quality iron in an amp is. But because it is the single most expensive part of any amp, it’s no wonder we see so many modern amp manufacturers skimp on the iron to keep costs down. Let’s see what the passionate, and often hilarious, Sergio has to say about his part of the business.

I’ve been seeing Mercury transformers in amps for at least a decade. When did you get into the amp scene?

This happens to be one of our most often asked questions. Even though Mercury Magnetics’ roots go all the way back to the early 1950s, there are guitar players who are only now discovering us. But if an industry insider like you has been aware of us for at least a decade, then I suppose it means I don’t need to lay off any of our sales and marketing staff.

I would attribute most of our lingering anonymity to the old days. Back then, most of our clients from the audio community preferred to keep us as a trade secret from their competitors and the press. The typical transformer-savvy amp builder also didn’t usually want to share the credit with us, or reveal what their “unique” technical advantage was regarding audio and tone. Consequently, we were asked to maintain a low profile and generic look for our transformers for quite some time. On occasion, a customer in the know will spot a small “MM” mark on a transformer from an older piece of gear, and ask if it’s a Mercury. Odds are that it is.

It was the guitar amp crowd that pushed us to go above ground. Now Mercury gives any electric guitar player or amp restorer a taste of what the pros were using, talking about in their studios, and amongst themselves. Many players have told us their amps increased in value when upgraded with Mercury transformers, and this became evident when insurance appraisers began to contact us for verification. However, it wasn’t until the mid-1980s when we began to market our services and various brands to guitar players.

For me personally, I got into the amp scene around the mid- to late 1970s. I just found it to be a nice way to relax from the strain of oversleeping.

Your website shows a large number of amp manufacturers you have replacement/upgraded transformers for. What are your best sellers and why?

There are so many different camps loyal to their particular amp brand, so it would be difficult to single out the best sellers. The best sellers are transitory and change from week to week because guitar amp players are a fickle bunch. That’s why we’ve built the world’s largest catalog of guitar amp transformers where nobody is left out.

But trends tend to follow their own dynamics. And the current worldwide trend seems toward smaller wattage amps—regardless of brand. Conversely, the 100-watt heads are not selling like they used to. Players are gigging with no more than 15 watts and a few pedals. Regardless of playing style, they’re doing just fine abiding by sound level restrictions and kicking ass with the tone we feel Mercury upgraded amps deliver.

These players really get the fact that an amp lacking in tone can’t be fixed with higher power or covered up with a gain mod. An amp that coughs out an asthmatic tone at 50 or 100 watts easily fatigues both music listeners and guitarists. But the audience will stay until the bar closes if the band plays well and sounds great—even with as little as a few watts going through the available PA system.

What can a guitarist expect to hear when upgrading their transformers in a newer amp?

An amp’s transformers are the most important component in determining the quality of amplified guitar tone. And it’s no coincidence that they’re the most expensive parts in an amplifier. Many of the newer amps just don’t have the same “overkill” factor with their transformers as the amps in the ’50s and ’60s. Why? Ignorance and a bean-counter mentality. What’s good for accounting isn’t necessarily good for tone from an amp. Sadly, the people making these decisions are probably not players themselves and don’t seem to realize the damage they’re doing to the industry.

It’s not unusual to find a current production amp with a power transformer running hotter than hell, even without cranking the amp all the way. Or having an undersized, cheaply built output transformer whose sphincter begins to tighten the moment the guitarist reaches for the amp’s volume knob. An amp built around anemic transformers yields only to dull, thin, noisy, fuzzy mids and mushy bass. That’s what makes your notes sound more like farts through a pillow. This overkill factor is probably the only edge that some of the vintage amps have over the newer amps.

We have made it our mission to duplicate the performance of the best original transformer designs of all time. In terms of amplified guitar tone history, these transformers represent the best ever produced. – Sergio Hamernik

Have you ever noticed how most newer amps often weigh less, sometimes a lot less, than the older ones? That’s usually the weight difference between the old and new transformer designs. There is a direct relationship between weight and having transformers that seem to stay cooler and “loaf around” with power to spare, until a player demands more from their amp. It’s like they are waiting around having a card game, waiting for the player to do something. The best vintage tone was born that way. Newer amp tone can be easily improved—if the builder follows some of the same ideas.

Upgrading with quality transformers gives a second chance to a new amp owner to make things right with their tone, by reclaiming that overkill factor. Assuming there are no issues with the amp’s circuitry like bad parts or worn out tubes, a guitarist should hear and feel improvements with the very first pluck of the guitar. They should expect to hear the notes more detailed with overtones, and a quicker and more immediate response to their playing. Clean notes will have less sonic collisions with noise and reveal more bell tones, chimes, etc.

When more distortion is required, the player will sense better control of crunch and when break-up begins to happen. The coughing and hacking that happens when a stock amp is pushed, will vanish with a transformer upgrade. It will be replaced with longer sustains and notes that reach farther. The amp will also sound closer and bigger than the power it puts out—and the bass notes will have a tighter, rounder bottom end. And when pushed, she will still be able to hold that quarter from dropping—no matter how tall her high heels—something most musicians are looking for.

It’s not uncommon for guitarists to report that it took a few weeks of playing to fully realize what they’ve gained in terms of harmonic richness. These players have typically played longer and felt more inspirational emotions sucking them in, as they have invested more time into relearning and becoming reacquainted with their amps.

Many players become very attached to the transformers in their vintage amps. When you create ToneClones or Radiospares and Partridge versions of these classic transformers, how close are they get to the originals?

Radiospares and Partridge are our brand specific clones, whereas ToneClones are “best-of-breed” duplicates culled from the hundreds of other brands that have made transformers over the years.

We have made it our mission to duplicate the performance of the best original transformer designs of all time. In terms of amplified guitar tone history, these transformers represent the best ever produced. In the grand scheme of tone pursuit, these designs are incredibility important and deserve to be considered treasures.

This is an ongoing project for us, spanning almost three decades now. And it couldn’t have been accomplished without the enormous amount of assistance we’ve received from top players and amp collectors around the world.

What about Axiom transformers? Where do they fit in?

The Axiom transformer line takes over where the limitations of vintage transformer design ended. No bean counters here—simply the sincere pursuit of answering the age-old question: What if there were no constraints on budget, time, or material quality to achieve the best possible performance? That’s our objective with the Axiom line.

Axiom transformer designs represent many new approaches—new tone with the best materials and designs money can buy, so they’re not intended for the timid or the low-budget crowd. Check out our FatStacks and SuperStacks for the Marshall DSL and TSL families for interesting comparisons.

Mercury’s vintage transformer restoration service has been gaining a reputation for quality work. Why would someone want to restore a transformer instead of replacing it? And vise-versa?

Some vintage amp owners prefer to pay the extra cost of our restoration services, because it’s very important to them that their amps retain authenticity. Collectables or rarities are valuable. They’re of the “why take chances” mind. The high road. But on the flip side, we have pro musicians who insist on touring with their vintage gear. To play it safe, and not sacrifice the tone of their original transformers, they have their techs replace the stock transformers with Mercurys. By doing this, they preserve the original transformers from road abuse while taking advantage of our reputation for tone, durability, and warranty. Restoration of vintage transformers is a tricky and highly specialized art. Sadly, too many of the great originals have been lost forever due to technically inept and musically disinterested people. We see attempts at “rewinds” here all the time.

Occasionally, it appears some people confuse “demolition” with “restoration,” and the preservation of the original tone is lost forever. There’s no shortcut to doing a proper restoration.

I understand you’re doing all of your labor and get all of your materials in the USA. How does that impact your business aside from just the straight costs?

Well, we figured that someone has to do it—and we really do make everything here with 100 percent American materials. There are plenty of products out there stamped with “Made in the USA,” but are actually assembled with non-USA, low-price materials. But yeah, we’re the real deal and proud of it.

Building transformers that make an amp sound good requires highly specialized technologies, highly skilled labor, and the right kind of materials. We love music and owe it to the players out there to do all the work “in-house,” so we can keep tight control over every aspect of our transformer designs. It’s really old-school military spec style, so our transformers don’t vary at all from batch to batch. If you need a replacement transformer 10 years from now, it’ll sound exactly the same as the one it’s replacing.

We’re hard-liners when it comes to not playing shell games with a musician’s hard earned dough and quest for better tone. Perhaps I’m a fool for doing it this way, but I was brought up in a musically minded family. From a very early age, I was taught that music is as important and necessary as food. If there is a day our services are no longer needed or appreciated, I’ll pursue my dream of owning a car wash in the valley, and get into the business of making money.

Any new or exciting projects in the works at Mercury?

Yes, but we’re planning on releasing the news sometime around summer. For quite some time, we’ve been fielding requests for accessories to accompany our transformer line. We’re being asked to apply our know-how to other aspects of guitar amps.

Do you have any advice for guitar players and techs in their quest for tone?

Don’t let anybody fool you—every player has the ability to discern the difference between good or bad tone. Unfortunately, there are a few too many self-styled “experts” who irresponsibly dispense advice without having a clue. As a result, we’ve all seen amps completely lose their tone by being modded to death.

There’s no excuse for the old “damn, I’ve done it this way for many years so it must be right” mentality. More than ever, it’s so easy to seek opinion, advice, and help online and elsewhere. I highly recommend the old textbooks from the 1950s and 1960s as a good place to start on vacuum tube audio circuits.

Do your homework and follow what the smart players are doing—improving your tone isn’t that elusive. If what you have sounds good to you, leave it alone. But if you know your amp’s tone could use some improvement, then start where it begins … the transformers.

Source: https://www.premierguitar.com/articles/Builder_Profile_Mercury_Magnetics

the way your nasty little amp makes you play…

So where does great tone come from if nearly everybody is using the same parts from a small circle of high production manufacturers? What gave vintage amps their great tone and why do some amps sound better than others? How come so many new amps don’t have that inspiring tone anymore? And where do babies come from?

The answer to (most of) these questions, and the absolutely mission of Mercury, is in the TRANSFORMERS. We’re not kidding when we call them the “heart and soul of your amp.” Transformers establish the character and behavior of your amp’s ability to generate tone, from clean, to dirty harmonic distortion. That’s why Mercury goes through the trouble and expense to build and tune transformers the hard way: by hand, one-at-a-time, with old-world craftsmanship and the most tonally effective materials money can buy. The end result is all the guitar tone you want without a speck of cereal.

But what does the future hold for the electric guitar player and vacuum tube guitar amp owner? Is there truly something out there beyond the limits of vintage tone that isn’t going to be solid-state? Yes, we think so. With just the right combination of know-how and passion, Mercury is now helping amp builders re-think guitar tone by re-inventing it. We call these new tone-generating machines Axioms. The Axiom line showcases new advancements in magnetics through transformer design. Designs that give amp builders better tools to work with and tone that we feel will better connect you to your guitar. All without following conventional vintage designs or recipes.

One fine example of Axiom-based advanced transformer technology is Mercury’s Epiphone Valve Jr. Kit*. What started out as a simple demonstration of Axiom transformers gave a $100 economy tube amp $1,000+ worth of tonal performance! It’s hard to believe there isn’t a vintage bone in their windings! We’re not surprised that this best-selling kit is fast becoming the first choice of pro players and recording studios alike.

Imagine an affordable entry into the world of boutique amps that delivers top-shelf vintage American clean tones all the way to the overdriven distortion of the old British amps. Also imagine an amp that totally responds to every tone knob and pickup adjustment setting on your guitar. It’s fun stuff!

Our little upgrade kit is a showcase of what the future has in store for harmonically-rich tone. We invite you to check out our Epiphone Valve Jr. Kit and hear for yourself just what everybody’s talking about. Or ask your amp tech about other Axiom upgrades for your amps. Remember, in addition to our already amazing-soundingToneClone and Radiospares lines we make Axioms for most popular amps.

Source: https://mercurymagnetics.com/pages/_misc/FAQ.htm#Give_me_your_dirty_tone

It doesn’t take too much digging to find a laundry list of boutique amp builders using Mercury Magnetics transformers in their products. From Mojave Ampworks to Joe Morgan Amps to kits from MetroAmp, builders have found that Mercury knows their iron. While transformers rarely receive the same level of attention of NOS tubes, speakers, or even guitar cables, they are a major contributor to tone. Think about it—the power and output transformers are the start and end of the line with any amp.

Based in Chatsworth, California, Mercury Magnetics has been building transformers for close to 60 years. I recently had a chance to talk with Mercury’s Sergio Hamernik to dig deeper into their roots, find out what one can expect from upgrading their iron, and what sets Mercury apart. Prior to our conversation, I had the opportunity to witness the remarkable transformation of an Epiphone Valve Junior modified from stock to hot-rodded, using one of their transformer upgrade kits. Not only was it a noticeable upgrade, it was a revelation in just how important the role of quality iron in an amp is. But because it is the single most expensive part of any amp, it’s no wonder we see so many modern amp manufacturers skimp on the iron to keep costs down. Let’s see what the passionate, and often hilarious, Sergio has to say about his part of the business.

PG: I’ve been seeing Mercury transformers in amps for at least a decade. When did you get into the amp scene?

SH: This happens to be one of our most often asked questions. Even though Mercury Magnetics’ roots go all the way back to the early 1950s, there are guitar players who are only now discovering us. But if an industry insider like you has been aware of us for at least a decade, then I suppose it means I don’t need to lay off any of our sales and marketing staff.

I would attribute most of our lingering anonymity to the old days. Back then, most of our clients from the audio community preferred to keep us as a trade secret from their competitors and the press. The typical transformer-savvy amp builder also didn’t usually want to share the credit with us, or reveal what their “unique” technical advantage was regarding audio and tone. Consequently, we were asked to maintain a low profile and generic look for our transformers for quite some time. On occasion, a customer in the know will spot a small “MM” mark on a transformer from an older piece of gear, and ask if it’s a Mercury. Odds are that it is.

It was the guitar amp crowd that pushed us to go above ground. Now Mercury gives any electric guitar player or amp restorer a taste of what the pros were using, talking about in their studios, and among themselves. Many players have told us their amps increased in value when upgraded with Mercury transformers, and this became evident when insurance appraisers began to contact us for verification. However, it wasn’t until the mid-1980s when we began to market our services and various brands to guitar players.

For me personally, I got into the amp scene around the mid- to late 1970s. I just found it to be a nice way to relax from the strain of oversleeping.

PG: Your website shows a large number of amp manufacturers you have replacement/upgraded transformers for. What are your best sellers and why?

SH: There are so many different camps loyal to their particular amp brand, so it would be difficult to single out the best sellers. The best sellers are transitory and change from week to week because guitar amp players are a fickle bunch. That’s why we’ve built the world’s largest catalog of guitar amp transformers where nobody is left out.

But trends tend to follow their own dynamics. And the current worldwide trend seems toward smaller wattage amps—regardless of brand. Conversely, the 100-watt heads are not selling like they used to. Players are gigging with no more than 15 watts and a few pedals. Regardless of playing style, they’re doing just fine abiding by sound level restrictions and kicking ass with the tone we feel Mercury upgraded amps deliver.

These players really get the fact that an amp lacking in tone can’t be fixed with higher power or covered up with a gain mod. An amp that coughs out an asthmatic tone at 50 or 100 watts easily fatigues both music listeners and guitarists. But the audience will stay until the bar closes if the band plays well and sounds great—even with as little as a few watts going through the available PA system.

PG: What can a guitarist expect to hear when upgrading their transformers in a newer amp?

SH: An amp’s transformers are the most important component in determining the quality of amplified guitar tone. And it’s no coincidence that they’re the most expensive parts in an amplifier. Many of the newer amps just don’t have the same “overkill” factor with their transformers as the amps in the ’50s and ’60s. Why? Ignorance and a bean-counter mentality. What’s good for accounting isn’t necessarily good for tone from an amp. Sadly, the people making these decisions are probably not players themselves and don’t seem to realize the damage they’re doing to the industry.

It’s not unusual to find a current production amp with a power transformer running hotter than hell, even without cranking the amp all the way. Or having an undersized, cheaply built output transformer whose sphincter begins to tighten the moment the guitarist reaches for the amp’s volume knob. An amp built around anemic transformers yields only to dull, thin, noisy, fuzzy mids and mushy bass. That’s what makes your notes sound more like farts through a pillow. This overkill factor is probably the only edge that some of the vintage amps have over the newer amps.

We have made it our mission to duplicate the performance of the best original transformer designs of all time. In terms of amplified guitar tone history, these transformers represent the best ever produced.—Sergio Hamernik

Have you ever noticed how most newer amps often weigh less, sometimes a lot less, than the older ones? That’s usually the weight difference between the old and new transformer designs. There is a direct relationship between weight and having transformers that seem to stay cooler and “loaf around” with power to spare, until a player demands more from their amp. It’s like they are waiting around having a card game, waiting for the player to do something. The best vintage tone was born that way. Newer amp tone can be easily improved—if the builder follows some of the same ideas.

Upgrading with quality transformers gives a second chance to a new amp owner to make things right with their tone, by reclaiming that overkill factor. Assuming there are no issues with the amp’s circuitry like bad parts or worn out tubes, a guitarist should hear and feel improvements with the very first pluck of the guitar. They should expect to hear the notes more detailed with overtones, and a quicker and more immediate response to their playing. Clean notes will have less sonic collisions with noise and reveal more bell tones, chimes, etc.

When more distortion is required, the player will sense better control of crunch and when break-up begins to happen. The coughing and hacking that happens when a stock amp is pushed, will vanish with a transformer upgrade. It will be replaced with longer sustains and notes that reach farther. The amp will also sound closer and bigger than the power it puts out—and the bass notes will have a tighter, rounder bottom end. And when pushed, she will still be able to hold that quarter from dropping—no matter how tall her high heels—something most musicians are looking for.

It’s not uncommon for guitarists to report that it took a few weeks of playing to fully realize what they’ve gained in terms of harmonic richness. These players have typically played longer and felt more inspirational emotions sucking them in, as they have invested more time into relearning and becoming reacquainted with their amps.

PG: Many players become very attached to the transformers in their vintage amps. When you create ToneClones or Radiospares and Partridge versions of these classic transformers, how close are they get to the originals?

SH: Radiospares and Partridge are our brand specific clones, whereas ToneClones are “best-of-breed” duplicates culled from the hundreds of other brands that have made transformers over the years.

We have made it our mission to duplicate the performance of the best original transformer designs of all time. In terms of amplified guitar tone history, these transformers represent the best ever produced. In the grand scheme of tone pursuit, these designs are incredibility important and deserve to be considered treasures.

This is an ongoing project for us, spanning almost three decades now. And it couldn’t have been accomplished without the enormous amount of assistance we’ve received from top players and amp collectors around the world.

What about Axiom transformers? Where do they fit in?

The Axiom transformer line takes over where the limitations of vintage transformer design ended. No bean counters here—simply the sincere pursuit of answering the age-old question: What if there were no constraints on budget, time, or material quality to achieve the best possible performance? That’s our objective with the Axiom line.

Axiom transformer designs represent many new approaches—new tone with the best materials and designs money can buy, so they’re not intended for the timid or the low-budget crowd. Check out our FatStacks and SuperStacks for the Marshall DSL and TSL families for interesting comparisons.

PG: Mercury’s vintage transformer restoration service has been gaining a reputation for quality work. Why would someone want to restore a transformer instead of replacing it? And vise-versa?

SH: Some vintage amp owners prefer to pay the extra cost of our restoration services, because it’s very important to them that their amps retain authenticity. Collectables or rarities are valuable. They’re of the “why take chances” mind. The high road. But on the flip side, we have pro musicians who insist on touring with their vintage gear. To play it safe, and not sacrifice the tone of their original transformers, they have their techs replace the stock transformers with Mercury’s. By doing this, they preserve the original transformers from road abuse while taking advantage of our reputation for tone, durability, and warranty. Restoration of vintage transformers is a tricky and highly specialized art. Sadly, too many of the great originals have been lost forever due to technically inept and musically disinterested people. We see attempts at “rewinds” here all the time.

Occasionally, it appears some people confuse “demolition” with “restoration,” and the preservation of the original tone is lost forever. There’s no shortcut to doing a proper restoration.

PG: I understand you’re doing all of your labor and get all of your materials in the USA. How does that impact your business aside from just the straight costs?

SH: Well, we figured that someone has to do it—and we really do make everything here with 100 percent American materials. There are plenty of products out there stamped with “Made in the USA,” but are actually assembled with non-USA, low-price materials. But yeah, we’re the real deal and proud of it.

Building transformers that make an amp sound good requires highly specialized technologies, highly skilled labor, and the right kind of materials. We love music and owe it to the players out there to do all the work “in-house,” so we can keep tight control over every aspect of our transformer designs. It’s really old-school military spec style, so our transformers don’t vary at all from batch to batch. If you need a replacement transformer 10 years from now, it’ll sound exactly the same as the one it’s replacing.

We’re hard-liners when it comes to not playing shell games with a musician’s hard earned dough and quest for better tone. Perhaps I’m a fool for doing it this way, but I was brought up in a musically minded family. From a very early age, I was taught that music is as important and necessary as food. If there is a day our services are no longer needed or appreciated, I’ll pursue my dream of owning a car wash in the valley, and get into the business of making money.

PG: Any new or exciting projects in the works at Mercury?

SH: Yes, but we’re planning on releasing the news sometime around summer. For quite some time, we’ve been fielding requests for accessories to accompany our transformer line. We’re being asked to apply our know-how to other aspects of guitar amps.

PG: Do you have any advice for guitar players and techs in their quest for tone?

SH: Don’t let anybody fool you—every player has the ability to discern the difference between good or bad tone. Unfortunately, there are a few too many self-styled “experts” who irresponsibly dispense advice without having a clue. As a result, we’ve all seen amps completely lose their tone by being modded to death.

There’s no excuse for the old “damn, I’ve done it this way for many years so it must be right” mentality. More than ever, it’s so easy to seek opinion, advice, and help online and elsewhere. I highly recommend the old textbooks from the 1950s and 1960s as a good place to start on vacuum tube audio circuits.

Do your homework and follow what the smart players are doing—improving your tone isn’t that elusive. If what you have sounds good to you, leave it alone. But if you know your amp’s tone could use some improvement, then start where it begins… the transformers. PG

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One of the common questions we receive here is, “How can I get my (fill in the blank with your favorite brand name) reissue amplifier to sound like the original?” Often times the question will contain additional information of what had been done already. “I’ve replaced the preamp and power tubes and gotten it biased, but it still sounds cold and brittle….”

My usual answer involves examining the guitarist’s rig by taking a “system” approach when looking for a particular tone. Often too much weight (i.e. blame!) is put on the amplifier, perhaps because it is the most electronically complex item in a typical signal chain. Countless times I’ve personally played with changes to an amplifier, whether modifying it, changing the tubes, etc. and still had poor results in overall tone! Now if you’ve got the wrong pickup or speakers for your needs, then obviously no change to an amp is going to help all that much….

But presuming all other areas of your guitar rig/system are covered, then let’s go back to the amp itself and talk about a particular upgrade that hasn’t gotten the attention it has deserved: the output transformer. In fact, dare I say that in many cases — for example a reissue amplifier — a change to a higher-quality output transformer will have a greater impact on improving the overall tone than playing with different brands of tubes. Essentially, if you’ve got the best tubes, or the worst tubes, but if your output transformer is a low-grade model, your tone will suffer no matter what you do.

“What the heck is the output transformer?,” you may ask. Well in layman’s terms, it’s the final connection in your tube amplifier that takes the signal from the tubes and transforms them into impedances and power suitable for your speakers. In further layman’s terms, it’s one of the big “metal blocks” that is attached to a typical tube amplifier’s chassis and is the connection link between your tubes and speakers. Most commonly, there are two large transformers in an amp — The other besides the output transformer is called the power transformer — that is the one that is responsible for taking the wall current and transforming it into the DC power used by your amplifier. While the power transformer is directly responsible for areas like supplying exactly how much voltage goes to your tubes and therefore can affect the response or “feel” of the amplifier, it is the output transformer that can dramatically affect the tone of your amplifier since audio signal is actually passing through it.

Like tubes, transformers can distort and color the sound, but in part because they are wired to an amplifier rather than just being “plug-in” devices, I feel they receive very little of the attention as to how much they can affect the tone. In fact, output transformers used to be thought of as simply items to be replaced when they failed. However, I can attest personally that in many instances a change in the output transformer to a quality unit as an upgrade can make a huge difference in tone — especially with those popular reissue Fender, Marshall, and Vox amps currently being made.

I recently was fortunate enough to try some units out made by Mercury Magnetics™ (www.MercuryMagnetics.com) with the idea being to install and listen to the various tones of some of their models of output transformers. The test-dummy amp used in the first case was a stock 1974 Marshall JMP 50 watt model 1987 Lead model — it had recently blown its output transformer after a tube had shorted a connection between two pins of the tube socket so it was the perfect candidate. The stock transformer still actually “worked” somewhat – but the power output was very low, probably about 1/5 of what the amp should have been producing.

Mercury Magnetics™ offers three choices for replacement 50 watt output transformers and I had the opportunity to try two of them. The units are part of the Axiom® or ToneClone™ series which are hand-built replicas of the original transformers used in the Marshalls of various eras. In addition to the Marshall replacement transformers, Mercury Magnetics™ also makes various other Axiom® models for classic Vox and Fender amplifiers in addition to other toneful amps such as Ampeg, Gibson, Hiwatt, and many others.

The models I tested were the Axiom® 050JM, a 50 watt output transformer model based on the earliest “plexi” Marshalls, and the Axiom® 050JM-SL, a similar model with the “Self-Leads” option. Both are priced at $150. The SL model differs from the standard 050JM in that it is made just like the earliest original plexi transformers were, where the solid copper core wire that is wrapped around inside the transformer continues outside of the transformer and is also the same wire used to connect to the tubes and impedance plug, etc. The solid-core copper SL wires outside of the transformer are covered by glass-cloth fabric material, just like that used on the original ‘60s models. Conventional transformers (including the non-SL version 050JM) use a different type of wire, often Teflon, that is spliced at the end of the solid-core wire that is then wrapped around the transformer inside. So what’s the big deal about the wire type? Oddly enough, it seems to really affect the tone of the output transformer — more on this in a moment.

Mercury Magnetics™ makes another model as well, the 050JM-M ($175), that is designed to be used in conjunction with modified Marshalls that require a beefier output transformer to better match up to the higher B+ plate voltages and other modifications or changes that run the amps harder. Since the ’74 JMP Marshall guinea pig was a stock model, I focused on the two plexi model variations, the 050JM and 050JM-SL.

The 050JM-SL was installed first. Since Marshalls sound best when run hard into power tube distortion, that’s exactly the listening environment I used. The head was run through a ’71 basketweave Marshall cabinet with G12M-25 greenbacks. The guitar was my trusty Les Paul Classic with a custom-specified Seymour Duncan Seth Lover PAF-type pickup. The tone of the amplifier with the 050JM-SL installed was brighter in the upper mids as well as the highs. The gain was a bit lower than with the stock Marshall’s output transformer (when it was properly functioning), but the clarity of notes and chords was definitely improved. The 050JM-SL is a good fit for players that like classic-rock and blues tones and perhaps need a bit more high-end cut through the mix. Usually additional highs are the last things that are needed with Marshalls, especially the amps and cabs made from about the mid ‘70s onwards. However, if you play through an earlier model Marshall loaded into a basketweave cab with G12-25s, “over brightness” really is not an issue and the O50JM-SL is the right match for this earliest type plexi tone. If you’re running a later checkerboard cab and a ‘70s JMP Marshall like our test model, the O50JM-SL may prove to have a bit more top end than what you’d want.

Moving over to the O50JM, I was amazed at how different this transformer sounded, even though other than the lead wires that exited the transformer, it has the same specifications and parts as used in the O50JM-SL! After installing it, I knew that the O50JM was the choice for the hard-rockers, whether using a plexi or metal panel-front Marshall. The O50JM had more distortion dirt and grind in the tone. Both transformers contributed to a very smooth response from the Marshall, but the O50JM traded off the upper frequency and some of the clarity content found in the SL model for what sonically resulted to its increased distortion and compression.

I also had the opportunity to hear the difference in a 100 watt reissue Marshall SLP after a Mercury Magnetics™ O100JM ($250: their 100 watt “plexi” output model) was installed and the results were even more staggering than the difference between the stock and upgraded 1974 Marshall 50 watts. I attributed this directly to the obviously low-grade output transformer used in the reissue Marshall. Crank up a stock Marshall SLP reissue and the transformer really does mask the tone — bright, grainy and cold are the words that come to mind as well as a pure lack of fidelity. The O100JM brought back the low-end warmth, made the top end smooth and the famous Marshall midrange crunch was back in the equation just like the original models. This is tone, pure and simple — and the reissue SLP held its own against my original ’68 100 watt Plexi Marshall.

One area worth mentioning is that Mercury Magnetics™ can also rewind original vintage transformers if you don’t want to replace your burnt out original vintage transformer. Mercury Magnetics™ replaces the internal windings and necessary parts but uses the original core and covers and then puts the transformer back to original specifications. This is ideal for the person who is looking to maintain their amp in a form that is as original as possible. This service is more costly than simply replacing the output transformer outright, but it will also help maintain an amp’s value so it makes a viable choice.

When looking into swapping out an output transformer, while it’s not extremely complex to do, it’s best to have a qualified professional technician do the job as tube amps contain lethal voltages that are stored inside the amp even when it is not plugged in. It can be a bit of a time-consuming job as you have to get underneath the amplifier’s layout/circuit board so the average charge by a technician to remove and replace the old transformer with a new one will typically run about $100 or so.

Shop for Guitar Amp Transformers

Whether you use your VOX AC4tv for practice, gigging or recording, take it to the pro-level with the Mercury Studio-Pro Upgrade. Experience the lush vintage tones that only Mercury transformers can give your amp.

Included in the kit:
-Axiom Power Transformer
-Axiom Output Transformer
-Axiom Mini-Choke™
-Other parts necessary to make the upgrade
-Fully illustrated step-by-step color manual, with wiring schematics and instructions

Kits are available in 120V only. Amplifier not included.

Mercury’s kit has everything you need to upgrade your Reissue Fender Champion 600 amp including detailed step-by-step, full color, illustrations, schematics and photographs to help guide you through the process. Installing our Mercury Upgrade Kit dramatically transforms your Reissue Fender Champ “600” (or Gretsch Electromatic) into a keeper.

Included in the kit:
– Axiom Power Transformer
– Axiom Output Transformer
– Axiom Mini-Choke™
– Other parts necessary to make the mod
– Fully illustrated step-by-step color manual, with wiring schematics and instructions

Note: Speaker no longer included.

Available in 120V only. At this time export versions are not available. Amplifier not included.

Complete upgrade kit for your Blackheart Little Giant amp head (BH5H) or combo (BH5-112). Our XLG Upgrade Kit requires only a transformer swap, and a few minor circuit board modifications. You can do it yourself, or we can refer you to an amp tech who can make the upgrade for you.

For our other Blackheart Little Giant Kit, see our Mean 13 kit.

Included in the kit:
-Axiom Power Transformer
-Axiom Output Transformer (4, 8, 16 Ohm Taps)
-Axiom Mini-Choke™
-Other parts necessary to make the upgrade
-Fully illustrated step-by-step color manual, with wiring schematics and instructions

Available in 120V only. At this time export versions are not available. Amplifier not included

Upgrade Kit for the remarkably inexpensive Epiphone Valve Jr. amp (combo or head). This demonstration Upgrade Kit features high-end, pro-quality performance transformers like those in great-sounding amps costing anywhere from hundreds to thousands more. Our Upgrade Kit makes the modified Valve Jr. the lowest-cost introduction ever to the wonderful world of boutique amplifier tone.

Ever wonder how much better your amp could sound just by upgrading its transformers? Here’s your chance to discover the night and day difference.

Included in the kit:
– Axiom Power Transformer
– Axiom Output Transformer (4, 8, 16 Ohm Taps)
– Axiom Mini-Choke™
– Other parts necessary to make the mod
– Fully illustrated step-by-step color manual, with wiring schematics and instructions
– BONUS! The “6V6 Mod.” Takes your Valve Jr. to even greater heights! Retrofits a 6V6 tube into the circuit. Allows you to run the EL-84 and 6V6 separately or in tandem.

Available in 120V only. At this time export versions are not available. Amplifier not included.

I have always had a passion for music and audio. Guitar tone through an amplifier aroused my curiosity early on because many of the design rules for hi-fi equipment didn’t apply to producing great guitar tone. In the case of vacuum tube amplifiers, transformer design has a significant influence on the characteristics of tonality. Unfortunately, there is not a lot of reference material available and many of the original designers have either retired or passed away. In the early 1980s my partner and I purchased Mercury Magnetics, a transformer design and manufacturing company, from one of the early pioneers who founded this company in 1954. Our close proximity to the Los Angeles recording industry gave us access to studio technicians and many well-known musicians. Out of necessity, and to meet the demands of this level of clientele, we had to develop precise, “no compromise” methods of documentation and assembly techniques to rebuild and replicate these transformers to exacting specifications. A past example of this was when a legendary guitarist sought our services to help solve a frustrating problem. A technician had replaced the original output transformer in his amp with a generic copy, which resulted in completely changing the character of the amp. Several breakthrough albums from the late 1960s and early 1970s were recorded using this particular amplifier, and the sound of that amplifier really had helped define his signature tone. Needless to say, most musicians are very concerned about maintaining the character and unique tonality of their amplifiers. We ended up rebuilding his original output transformer and we provided two additional clones as backup.

TQR:Are you referring to all types of guitar amps, or more specifically British amps rather than, say, vintage Fenders?

I think that in all guitar amps, regardless of origin or brand, you also supplying custom transformers to amplifier manufacturers. Our extensive collection of vintage transformer designs really began to take off at that point in time. The ongoing accumulation of the finest sounding examples we could find inspired our line of ToneClone® transformers.

TQR: What is it about those particular transformers that make them so special, and how do you evaluate them? Do you install them in an amplifier and A/B them, or is it done more or less on paper?

We do have the necessary test equipment and software to check various parameters, but ultimately the ear has to make that decision. We also plug in, play, and conduct A/B testing at our facility. I have a dedicated sound room at home that has been tuned for the purpose of testing and evaluating audio equipment. We are lucky, because the Los Angeles area offers us an amazing amount of guitar playing talent that continues to help us maintain a level of objectivity. Also, some of our best listeners are avid tone enthusiasts who work in and for the local studios. These people understand good tone and give us their experienced opinions.

TQR:And can you describe what it is that makes these transformers special? What would we hear, specifically?

Having a detailed transformer spec is only the beginning. Breaking down into fine details what materials and assembly techniques were used decades ago helps 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, the Axiom and ToneClone series are only available in limited quantities. Consequently, there is an audible difference between a budget transformer and an Axiom or ToneClone.

TQR:Can you describe the audible differences?

A good output transformer should go beyond its job of impedance matching, and 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 eeking. Better said, we still can’t make an apple into an orange.

TQR: What are some of the comments that you hear from players when they hear the Axiom or ToneClone transformers that you build? Is it a matter of touch dynamics, harmonics, all of that?

Yes, and let’s not forget musicians’ colorful tone speak, such as: The amplifier sounds more open, glassy, sweet, brown, fat, with more notes perceived. Barred chords are not muddy or squashed. Chimes and bell tones are much more apparent. Good note separation, sustain improved, more definition, etc…

TQR:And these things can all be affected by the output transformer in some considerable detail….

It 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, also affects tonality. The ghost note phenomenon would be an example.

TQR:Like a few amplifier builders we know, you have taken the direct route of precisely replicating the materials and tolerances that comprised the industry standard decades ago…

I remember having a conversation with Leo Fender a number of years ago and getting a chuckle out of him as he told me how amazed he was that so much scrutiny was being given to how things were done in the early days of Fender. He said that they had taken what they were doing in the ’50s and ’60s so matter of fact back then. They were hardly thinking at the time that they were building future classics. They were trying to make an affordable, good sounding, quality amplifier while still trying to make a buck. Leo also mentioned that for reasons of cash flow and/or inventory problems, they would resort to using alternate vendors from time to time. They kept a careful eye on cost of materials, and their supply, rather than hand picking components with alleged magical tonal qualities.

TQR:They weren’t matching tubes, either. All of this can and does get out of hand, but when your rig sounds so good that you can get lost in the magic of it, as a player, wonderful doors can be opened.

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?

TQR:That leads us to an interesting situation in which the original output transformer in our ’60s Pro Reverb died, and we noticed how much better the amp sounded when we had installed a new transformer, which was a commonly available unit sold by MojoTone. Now, the amp sounded great before the old transformer went out, but it sounded significantly better with the new transformer. I asked our tech and advisory board member Jeff Bakos if it was possible for an output transformer to gradually decay over time, dying a slow death while you continue to lose ‘tone’ in a very subtle fashion over years of use. Is that possible? It seems as if that was the case with our amp, which we had always considered to have a rather legendary vibe.

Not only is it possible, it is probable. Keep in mind that if high voltage insulation breakdown has started, there is no reversing it. Assuming that the transformers insulation system is intact, we have in the past reversed some tonal degradation in original transformers under controlled laboratory conditions. I’ve proven that point with my more cynical, high-end customers. One example of this is an amp (a Marshall JTM 45 or a Plexi – I forget which) that had been used in England for years and then brought over to the United States. The owner felt that the tone had decayed over time, seeming darker, lifeless, and the higher frequencies were less pronounced. We asked him to remove the transformer and all we did when he brought it in was to re-bake it in an oven to drive out the moisture. We then vacuum impregnated the transformer with our proprietary resin to hermetically seal it before the final bake. He put the transformer back into the amp and the results were 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, however….

TQR: No, but it seems to be a fair statement to say that it’s possible that your good sounding old amp might sound significantly better with a new output transformer. At least that was our experience, and in hindsight, we didn’t realize what we had been missing.

That’s true. The tonal degradation I’m speaking about is very slow and gradual. Your results would be even better if you had used ToneClone transformers. Any of our transformers should outlast older vintage transformers because each are put through the same process during production.

TQR:Doesn’t it become particularly more problematic with amps like AC30s and Hiwatts, where repro transformers have typically been poor compromises at best?

I believe that Marshall, Vox and Fender, to name a few, are doing an outstanding job of building affordable vintage reissue amplifiers. When an owner of one of these fine amps wants to take his/her tone to the next level, they will usually consult someone like a Don Butler (Toneman) for example. Don is an expert in the field of amplifier upgrades and the art of tonal improvement. Don is also one of the key figures in this mini industry, which is similar to the aftermarket for automobiles and motorcycles. Much like an engine tuner, Don will replace transformers and other components in the signal path to give the customer an upgraded, outstanding sounding amp that comes much closer to capturing the original tone they were seeking.

TQR:Your website seems to be very comprehensive, but can you be contacted over the telephone for customers that either don’t see their amp listed or perhaps have additional questions?

Yes! Paul Patronete, an accomplished guitarist who has a good ear for vintage tone and heads our MI division, is happy to help those customers when I am unavailable. Our website is constantly being updated with vintage and modern transformer versions. We will probably always be two or three 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. Another cool thing we offer are modern, updated versions of many of the classic transformers. We have added output impedance taps for many of the classic Fender transformers, which were never originally offered. For any make of amplifier, we offer various mounting styles from the original. We can, in addition, alter tonal characteristics to fit the unique needs of each customer.

TQR:Are you building transformers for many small builders?

Yes. If you own a high end, small production amplifier, there is a chance you will find a Mercury Magnetics label on the transformers. Some exceptions are when certain amplifier manufacturers remove labels in an effort to keep us and other vendors a secret. We do maintain a confidentiality agreement with all of our customers if this is their desire.

TQR:Schumacher was a primary supplier to Fender during the tweed era, and they are still operating, although we understand that you generally have to be capable of placing a fairly large order to get geared up. That seems to be a significant barrier to many would-be amp builders.

That company is doing a good job of supplying inexpensive transformers to a high volume market. When a lot of emphasis is placed on meeting price points, something has to give. The cost of labor and materials are logically their first consideration. The end result is a compromise, and who could blame them? Ultimately, end users will determine if the resulting tone is adequate. Someone who has paid several thousand dollars of their hard earned money for a “high end” amp is expecting to have something that excites their senses along with a build quality that justifies their investment. This is where we can assist the amp builder. It goes beyond Mercury Magnetics “sending in the clones.” We have made every effort to break those barriers by eliminating minimum buy requirements. We work closely with today’s designers and builders to provide them with a thoughtful, next-level approach to their signature tonal requirements.

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Mercury Magnetics

As I mentioned earlier in the article, I had not originally intended to use a Mercury Magnetics power transformer (PT), electing instead to save a little money and use the stock DRRI PT. I’ve since changed my mind. How this came to be makes for an interesting story.

About 10 days before I was scheduled to pick up my amp at Mikey’s shop, I sent out emails to all the companies that I linked in this article. This included Mercury Magnetics since Mikey was putting their output transformer, reverb transformer and choke in my amp. Shortly after sending out an email to Mercury, I heard back from Paul Patronete who graciously gave the OK to link to their site. He also took a moment to let me know in addition to the other Mercury iron I was using, their power transformer would make an improvement in the tone of my amp. Paul invited Mikey and me to give Sergio Hamernik (an owner of Mercury Magnetics) a call to discuss the benefits of the power transformer.

I really appreciated the helpful suggestion but I hadn’t ever heard of a PT making a difference in tone, thinking the other pieces of Mercury iron would make 90% of the improvement. I did let Paul know I’d add a comment in this article saying I’d heard from Mercury and the PT would make a big improvement in the tone. He wrote me back with an interesting bit of information I had never considered. Here’s a paraphrase from the email he sent me:

The stock reissue PT does an OK job of supplying the required voltages to the circuit however the overall PT’s behavior under working conditions is not the same as the original vintage Deluxe Reverb PT. Characteristics that make the reissue PT different than the original PT involve flux density, AC regulation and primary inductance. These characteristics are a very important factor for the player that wants to nail the tonality of the vintage Blackface Deluxe Reverb amp.

Paul once again encouraged me to talk to Sergio. This certainly piqued my interest so I got in touch with Mikey and discussed Paul’s comments. We decided to get Paul on a conference call and to also see if we could speak to Sergio. We called Mercury in the late afternoon, four days before I was due to pick up my amp. Although Sergio wasn’t in, Paul spent almost 1.5 hours talking with Mikey and me about their power transformer and the rest of their iron.

Paul is a guitar player first and foremost and his enthusiasm for great tone is infectious. In addition to talking about all the good things Mercury Magnetics has brought to the industry and guitar players, he talked about what some of the cutting edge builders are doing. Mikey and Paul had very similar opinions on what makes great tone and why. It was a very informative and fun conversation. At the end of it, I certainly wanted to speak to Sergio so Paul invited Mikey and I to call again in the morning.

The next day, Mikey and I called Paul and after a brief chat, he brought Sergio to the phone. It was truly a treat to talk with Sergio and I learned a LOT about tube amps, the importance of an amp’s magnetics (the iron) and primarily, the benefits of using a Mercury Magnetics power transformer engineered for a Deluxe Reverb. As we talked, I jotted down as many notes as I could manage. I’ll share them with you now, although please keep in mind I may not have captured everything Sergio was conveying. He did a fine job though of keeping his information geared to my level of understanding.

Sergio started by asking me if I knew what modulation is. Of course I’ve heard the word but I wasn’t sure what it meant in relation to tube amps. He explained that an amplifier is a modulated power supply whereby the guitar signal is used to modulate the amp and so the quality of the power transformer affects tonality. He said the power transformer (along with the rectifier tube, a 5AR4 type) is responsible for taking the AC wall current and transforming it into the DC current used in certain parts of the amplifier. He said the power supply sets everything else up and everything depends on the character of the power supply. For example, since it helps determine the AC and DC voltages going to each section of the amp and tubes, it has a big impact on the feel of the amp.

I learned that although the stock DRRI power transformer provides the right amount of volts and amps (current) to the amplifier, the DRRI power transformer is nothing like one of the original PT’s used in Deluxe Reverbs. Sergio said among other things, the flux density and primary inductance all have to be right. As a comparison, the DRRI stock power transformer has 1/2 or less inductance on the primary than a Mercury Axiom PT. (You may recall from a previous section; inductance is the opposition to changes in current.)

He said capacitance and leakage reactance are critically important and Mercury Magnetics power transformers have lower flux density and heavier iron with better permeability. Capacitance and leakage reactance between the windings, and where the filaments are in relation to the B+ supply, really matters. Now that’s a mouthful! I think I’ll need to spend some time researching the concepts mentioned in just the last two paragraphs so I can better understand the electrical theory behind his designs. One of the best things about this project and writing this article is being exposed to new concepts. This is my idea of fun!

Sergio did break this theory down into practical examples for me. He explained the Mercury Magnetics method starts with finding the very best sounding amps and examining their iron. For example, if there is a great tone on a recording, Sergio can try to find the exact amp used on the recording and use it as the model for new iron.

Mercury Magnetics’ Axiom power transformer for a Deluxe Reverb (not for a DRRI)

The DRRI power transformer has different physical dimensions than the one in a Blackface Deluxe Reverb. Mikey has an electronic caliper that does very precise measurements so he sent these dimensions to Paul so Mercury can provide the perfect power transformer for this amp. They have the know-how to build power transformers that will sound just like one in a Blackface Deluxe Reverb. They do this by using the very best example of an original 1965 Deluxe Reverb transformer, unwinding it and laboriously documenting every nuance of how it is constructed. Then a combination of old and new technologies is used to create the very best transformer possible.

There’s a reason why guitar players seek out older amps, and this obviously is because of better tone, which I’ve come to understand is largely due to quality magnetics. I learned the magnetics available to amp builders in the 50s and 60s were made from materials optimized for the military for WWII and the Korean War. There was a tremendous overstock from the military build-up and amp builders had ready access to very high quality materials.

Modern materials are designed to be cheaper to hit price points. Sergio told us he specs custom steel to make Mercury transformers. They do enough volume of business that he can insist his steel manufacturer hand crank the steel through a gas oven, just like it was done in the 50s and 60s. Steel and copper behave differently at different milliamps so the properties of the metal must be designed and manufactured to this end. For the guitar player, this level of quality shows up in things like the ramp rate of note attack, the feel of the pick attack and better bass note response. He also used the choke as an example, where the Q-Factor (the measure of quality in a resonance system) is quite a bit different between the stock DRRI choke and the Mercury choke, so much so that it makes for an audible difference.

Sergio explained the power transformer is rated for a lot more watts than the amp produces. For example, the Mercury Magnetics Axiom power transformer for my amp will be rated at 120 watts and is capable of supporting an audio output of up to 60 watts. The general rule-of-thumb is the power transformer needs to be rated at twice as much as the maximum audio output.

Since this power transformer has specs well in excess of what the two 6V6 tubes are capable of creating, it can safely run 6L6 tubes. 6V6 tubes require only 60% of the power of 6L6 tubes. The output transformer is also capable of handling 6L6 tubes so by getting the Mercury Magnetics power transformer, I can get more power and a different tonality out of my amp than with the 6V6’s. This is a nice bonus and one I hadn’t considered when Paul first emailed me, suggesting their PT. I prefer 6V6’s in the amp but it’s nice to have another option.

Mikey asked Sergio to describe the sonic differences we might expect with the use of the Mercury Axiom reverb transformer. Sergio said the sound differences are subtle because it is such low power but if you have good ears, you’ll hear differences in “evident detail” and a “perceived wider bandwidth.”

Mikey and Sergio talked a bit about the dramatic effects of using the Mercury output transformer. Sergio likened his output transformers to a window with no glass and no screen, allowing all of the tonality of previous sections of the amp to pass through with great clarity. He explained the excellent “phase relationship tonality” (perceived as a 3 dimensional swirl) is dependent on the quality of the construction of the transformer. By comparison, the DRRI output transformer acts as dirty glass covered by a dirty screen. I couldn’t help but be reminded of the scene from the movie “My Cousin Vinny” where Vincent Gambini (Joe Pesci) disproved the testimony of a witness by pointing out with pictures how the witness was looking through dirty glass, a bug covered screen, and through trees and bushes at a fleeing car.

As a tube amp enthusiast, I’ve been reading and learning about tube amp electronics for quite some time. In this conversation with Sergio I learned a lot of things I had never considered. Of course, by now I was completely convinced their power transformer should go in my amp! You can understand why the top amp builders call upon Sergio for his expertise, designs and remarkable archive of information.

If you take a look at the Mercury Magnetics site you will find a large selection of iron to fit just about every need (www.MercuryMagnetics.com).

Sergio and Paul both told us there were very significant differences in iron on the same models of amps from the same era. Sergio spoke of a conversation he’d had with Leo Fender about amp components. Leo told him the Fender Company experienced a swelling of demand for amps when young people became enamored of guitar. Fender was just trying to meet the enormous demand so they put out specs for things like power transformers to various suppliers. The suppliers had a lot of latitude in how they meet the specs, creating a lot of variation in the parts.

Here’s another new bit of tube amp knowledge I learned from Sergio. He told me all magnetics (iron) in an amp need to be broken in over a 20 to 40 hour period of playing time. He said initially, there’s a slight harshness in the tone, which can also be characterized as a lack of sweetness. The magnetics have to be thermally and magnetically cycled. Apparently, it is similar to breaking in a speaker. Paul later told us he’s had guitar players call him up after a month to describe the new subtleties and complexities emerging from the amp: a wonderful and unexpected surprise.

After spending about 45 minutes on the phone with Mikey and me, Sergio turned us back over to Paul. I must say it was a pleasure and an honor to speak with Sergio and he couldn’t have been more gracious in taking his time to explain all of the information I’ve relayed above.

Paul and Mikey made arrangements to take the exact measurements of the bolt placement and chassis openings in the DRRI for a new power transformer. I sat back for a bit as Paul and Mikey continued where they’d left off the night before, talking about new amp ideas Mikey has been considering, which will involve creating an amp using a wide variety of power tube options. It’s too early to go into details about that though. I’ll have to save that for another article :>)

By the way, we got to know a bit more about Paul Patronete. He is a key associate of Sergio who talks with guitar players and amp builders all the time, helping people decide which Mercury Magnetics iron is right for them. You can tell he really gets off on helping players attain tonal nirvana.

Of interest, before coming to Mercury Magnetics, Paul was the General Manager for Groove Tubes for many years. I dug out my copy of Aspen Pittman’s “The Tube Amp Book – 4th Edition” and sure enough, there is a picture of Paul on the inside of the back cover. He’s also listed in the very front of the book in the “Strokes for My Folks” page and a color photograph of his Orange amps is also in the book.

Well, I’ve gone through all of my notes from my discussions with Paul, Sergio and Mikey so I guess it is time to close this chapter. I’ll be picking up my amp tomorrow although it will have the stock DRRI power transformer in it until a new one is manufactured. I sure am glad Paul took the time to talk to me, educate me, and with Sergio’s help, convince me to get a Mercury Magnetics power transformer to go along with the rest of the Mercury iron in my amp. I’ll make another trip to Mikey’s shop in Baltimore next month and I’ll be sure to let you know how it sounds, so stay tuned.

Source: https://mercurymagnetics.com/pages/news/misc/WayneReno.htm

It’s our simplest Upgrade Kit, yet. All you (or your amp tech) do is swap the transformers and make a few minor circuit mods. The kit also includes an optional Pentode/Triode mode selector switch that expands the tonal possibilities even more!

Also included in the kit:
– Axiom Power Transformer
– Axiom Output Transformer (4, 8, 16 Ohm Taps)
– Other parts necessary to make the upgrade
– Fully illustrated step-by-step color manual, with wiring schematics and instructions

Also consider adding our 9 Henry Mini-Choke for a big affect on the overall tone and feel of your amp.

Available in 120V only. At this time export versions are not available. Amplifier not included.

Your quest for truly inspirational and superior tone has led you to the final link in the chain – Mercury Magnetics. Premium guitar amplifier power transformers, output transformers and chokes.

Transformer sets are often misunderstood, yet vital musical components. They’re integral to the nuances of your guitar amp’s sound. Far more than tubes, speakers or other amp components, the transformers establish the platform for shaping your amp’s unique sound.

Today’s players are more informed and demanding than ever. They hear the differences and know that both transformer design and build-quality have a dramatic effect on their tone. Indeed, if your tube-based amp is suffering from bland and unexciting tone then it’s probably related to low-end or poorly designed transformers. As amp designers, techs and manufacturers have discovered, the practice of dumping generic, low-bidder transformers into their amps doesn’t cut it any more. And now you know why.

Who uses transformers by Mercury Magnetics?

• The Who’s-Who of top guitar players.
• The majority of top boutique amp makers, world-wide.
• Amp manufacturers who produce high-end and signature gear.
• .. and players like you who are crave the best possible tone from their amps.

Within the player community no other company commands as much respect as Mercury Magnetics. You can depend on our uncompromising, fanatical build quality, consistency and reliability.

All of our transformers are 100% handmade by us here in California, USA. They come with an unheard of 10-Year Workmanship Warranty as well as a money-back Tonal Satisfaction Guarantee.

Who is Mercury Magnetics and why  is our guitar amp project so important to you?

Did you know that tube-based guitar amp transformers are unusual and very different from industrial as well as audio transformers? And did you also know that it is impossible to engineer the “perfect” guitar amplifier transformer from strictly “by the book” specifications? Interestingly, almost all of the great-sounding amp transformers contain either flaws, “happy accidents,” or have other issues in their construction that were not part of their original specifications.

Decades ago, when Mercury’s engineers first discovered these curious phenomena, the music industry was already in the process of losing its references to tone. In the throws of converting to solid state, tube and transformer platforms were mistakenly being relegated to relics of the past. Those who knew the original technology were either retiring, dying off, or jumping ship for the “new improved” way of doing things. By the time we collectively began to realize what was happening to guitar tone, it was almost too late. “Old school” manufacturing had been all but shut down and as quality dwindled N.O.S. (new old stock) components became the last bastion of our tone.

It was during those Dark Ages that the transformer connection to tone was almost lost completely. However, Mercury was there as a hold out — and even when it wasn’t fashionable, never compromised. But as often happens, when an older era fades, the remnants of what made it great were readily available to study. And like archeologists, Mercury’s engineers began sifting through the bones of the most coveted old amps in an attempt to discover what made them better, and often times so different than others.

The resulting products of those studies were the earliest ToneClone and Axiom designs. Mercury quite literally evolved a new science of guitar amp transformer design for tube-based guitar amps from there, and has continued to innovate and revolutionize it since. Perhaps few people realize the significance of these discoveries and the resultant developments. But without Mercury’s catalog of transformer designs, guitar tone as we knew it would have been lost.

We build transformers exclusively for guitar amplifiers. And we’re unique in a number of related ways:

• 100% American made — no hidden imports — we really do make ’em from scratch, right here in California!
• 100% handmade and hand-tuned using only handwound components. We never compromise or play bean-counter games by short-cutting, attrition or using cheaper materials. Each and every transformer is consistent. If you ever need to replace one of our transformers, your amp won’t lose its tone — your replacement will sound exactly the same as the original.
• American-made steel — we’re the only transformer manufacturer who custom orders, from an American steel mill, the unique alloys used in our transformers. These alloys are not only made here in the USA to military specifications, they are not available anywhere else in the world. They’re the same alloys used in the all-time best-sounding transformers during the “sweet spot” era (pre-1965) of guitar amplification history.
• Things are never stagnant around here. Mercury maintains active and ongoing R&D (research & development). All kinds of new and exciting-sounding transformer designs (Axiom series), as well as our ongoing cloning of outstanding transformers mined from the great old amps (ToneClone series). For vintage British amp freaks, check out our Radiospares, Hiwatt and Partridge series. And many modern amps can be upgraded with our APS series — our newest line of guitar amp-specific transformers.
• For any popular amp design we’re likely to have not just one but several transformers for different purposes and different tonal characteristics. It’s always a smart idea to discuss replacement, restoration or upgrading with your Mercury rep. — you’ll find his input invaluable.
• Our transformers are found in the amps of virtually every major player in the world. Many specify Mercury and won’t play an amp without them.
• Mercury transformers are standard components or factory upgrades available in virtually all high-end boutique amps, including Fender’s boutique and custom shop lines.
• Mercury transformers are so highly rated that they typically increase the value of any amplifier they’re installed in.

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

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?

Legalese and stuff:

All Mercury Magnetics® products are 100% handmade in California, USA.

Copyright © 1954-2025 by Mercury Magnetics. All Rights Reserved. Mercury Magnetics, Mercury Vintage, Partridge, FatStack, SuperStack, NewVolt, Mini-Choke, Multi-Choke, Mercury Custom Shop, Mercury Boutique, “The Heart & Soul of Your Amp,” “Holy Terror,” “Bad Guitar Tone — Whatever Its Evil Mission It Must Be Stopped!”, “Champ 600 Upgrade,” “XLG Upgrade Kit,” “Mean 13” and “The original British amp tone — shaken, but not stirred,” “Our Transformers are Stacked,” “The Essential Building Blocks of Your Tone,” “Mercury Studio-Pro Upgrade Kit for the VOX AC4tv,” UTM (Universal Transformer Mount), Amp-Saver and Copper-Tone are trademarks licensed to Mercury Magnetics. Axiom, ToneClone, Radiospares, VoodooScrew, Multiple Arrayed Geometric Inductive Coupling (M.A.G.I.C.), and APS (American Pro Series) are registered trademarks licensed to Mercury Magnetics. All other companies, products and trademarks mentioned on this website are trademarks of their respective owners. Unless otherwise noted Mercury Magnetics is not affiliated with any of these companies.

Mercury Mod and Upgrade projects and their documentation are the result of technical investigations made by the engineering staff of Mercury Magnetics. The disclosure of the information herein may pertain to proprietary rights, and the furnishing of these documents does not constitute an expressed or implied license to use such materials.

Mercury Magnetics® transformers and other products are in compliance with the European Union RoHS Directive 2020/95/EC with respect to the following substances: lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CR (VI)), polybrominated biphenyls (PBB), and polybrominated diphenyl ethers (PBDE).

Mercury Magnetics® founded in Southern California in 1954 and incorporated in 1968.

CAUTION!

The voltages in your amplifier can be dangerous. Transformers and chokes are not user serviceable parts. Installation of these components should always be performed by an experienced technician.

The simple ability to use a soldering iron is not enough to qualify a “do it yourself person.” Those who are inexperienced in working with electronic circuits should never attempt to service their amplifier. Household line currents can be deadly!! Transformers, chokes and large filter capacitors can store a dangerous charge for several days or more after the amplifier has been unplugged. Never touch the terminals of such devices without being certain of their charge status. Risk of shock and damage to equipment may result from mishandling and/or improper use of these components. Please use common sense and always think safety first. After all, tone is most enjoyed when you are alive to hear it.

With permission, Mercury’s logos and artwork may be used on websites, printed advertising, business cards, affixed to MI products that contain Mercury’s transformers or chokes, and other product as well as promotional material. For permission or other special uses, please contact Mercury’s sales department sales@mercurymagnetics.com for details.

LOGOS

Mercury Magnetics

“The Heart & Soul of Your Amp”

ToneClone

Axiom

Radiospares

Mercury Custom Shop

Mercury Vintage

PHOTOS & ARTWORK

“Beauty” shot #1

“Beauty” shot #2

“Beauty” shot #3

“Beauty” shot #4

“Beauty” shot #5

Source: https://mercurymagnetics.com/pages/SSN/pages/MercArt.htm

Requests for educational consumer handouts about Mercury have been pouring in. So, we’ve designed this simple P.O.P. (point-of-purchase) display to make information on Mercury’s quality transformers available. The brochure discusses transformer upgrades and restorations, as well as our ToneClone, Axiom and Radiospares lines of vintage and next-generation products. A must-read for any guitar player!

Help your customers to learn more about the sonic-qualities of great transformer designs. Our eye-catching display is designed to hold 40 Mercury Magnetics “Unleash Your Amp’s Tone!” brochures.

BROCHURE PAGE 1

BROCHURE PAGE 2

It’s available for dealers and resellers — free! Getting a display for your store is easy — just give Patrick a call (or email) and ask for one!

Source: https://mercurymagnetics.com/pages/SSN/pages/POP1.htm

Hey, Jeff.

I love your column! I look forward to reading it every month. I have a ’67 blackface Super Reverb that I gig with. Really an awesome-sounding amp!

I just realized that the output transformer has been changed to a Bassman reissue or a Super reissue OT (output transformer). I’m not really big on keeping it original — it doesn’t really matter to me because I will never sell this amp — but like every other tone searcher out there, I want the best possible tone that this amp can achieve. I am curious about changing this out for a higher-quality OT. I heard the Mercury transformers are really good vintage replacements. What kind of differences in sound/tone will I hear by doing this, and is it worth it? Also what kind of tubes do you prefer in these amps? Thanks so much, and keep the awesome columns coming!

Ben

Hi Ben,

Thanks for reading PG, and thanks for writing in. It’s the much-appreciated support of the readers that enables all of us to write for such a cool publication. Now… on to that horrible amp you’re forced to gig with. I kid, of course. The Super Reverb is absolutely one of my favorite amps. The multiple 10″ speaker configuration helps give it a unique voice and sets it apart from most other combos using the ubiquitous 12″ speaker. It’s a shame that the output transformer needed to be replaced, but occasionally these things happen. A reissue Bassman or Super Reverb transformer, since they both have an output impedance of 2 ohms, will certainly get the amp working properly, but yes, you can do better.

Mercury Magnetics offers a couple of different lines, and they are some great-sounding replacement transformers. Their ToneClone series transformers are replicas of the original transformer designs, and the Axiom series takes them to the next level with design modifications for tonal improvement. Which one you choose will depend on whether you desire to have the amp sound as good as a great-sounding Super Reverb can, or to, as Emeril Lagasse says, “Kick it up a notch!” Either way, you should notice tonal improvements. Some may be very noticeable, and some may be subtler. Things like tighter, extended bottom end, smoother top end, more harmonic content and better note definition are all improvements you might expect. These attributes can all be affected by the quality of your output transformer. Whether it’s worth it or not is completely dependent on any cost limitations you put on your search for the ultimate tone.

You also asked about tube preference. This is always very subjective and depends on the type of music you play and your expectations of the amp. In general, my preferred preamp tube for amps that were not designed with heavily overdriven preamp sections is the Sovtek 12AX7LPS. Its large plates seem to make it a very full-range tube, so your guitar or effects will be very full bodied. In amps with major front-end gain, this extended frequency range can become too much of a good thing, but that’s certainly not the case with a Super Reverb like yours.

Also, here’s a little helpful tip to remember: Even new tubes can be microphonic. If you install new tubes in your amp and you experience ringing or feedback when the volume is turned up with nothing plugged in, try swapping the positions of all the tubes of a same spec. (In this case, it would be the 12AX7s. The 12AT7 tubes in Supers are in locations that are generally not too susceptible to microphonics, so they shouldn’t be an issue.) Certain locations in the circuit are more susceptible to microphonic tubes than others, so moving them often clears up the ringing, or at least minimizes it.

Preference for output tubes is much more dependent on the use of the amp and style of music. If you play mostly blues or classic rock, I would recommend going with a smaller-bottle tube that will have a nice, smooth breakup that occurs sooner — making it easier for the output stage of the amp to be pushed into clipping and achieve that glorious nirvana that is output-tube distortion! Recommendations might be the new reissue Tung-Sol 5881 or Groove Tubes GT-5881C. If you’re more into big jazz chords or country twang — or if you get your signature tones from stompboxes and prefer that the amp be as big, loud and proud as it can be — you’ll probably want to go with a larger-bottle tube. This generally yields the fullest, cleanest performance. Recommendations here might be the JJ/Tesla 6L6GC or the Ruby 6L6GCMSTR. Another suggestion here might be the new reissue Tung-Sol 6L6GC-STR. I just installed a quartet in a Twin Reverb and it was surprisingly loud ‘n proud. I hope that helps you on your way to a more super Super.

In this issue we are dealing with a subject on which I have received many inquiries in the past. It is about the selection or matching of tube amps for the best possible Jazz sound. Amplifying acoustic or semi-hollow-body guitars has always been a huge challenge because most jazz guitarists are very demanding in terms of sound and simultaneously fight against unwanted distortion and feedback. In the following article I would like to summarize some tips and tricks that get  great tone and how to avoid distortion.

When I started getting involved with jazz sounds, around 1977, most guitarists in this genre used transistor amplifiers. George Benson played a Polytone, Pat Metheny an acoustic amp with a 4×10” speaker cab and Volker Kriegel and Michael Sagmeister used a Gibson LAB L9 with 15” speakers. Such examples can be found very often from that period. Although all of these guitarists had indeed very good tone, the typical depth and openness of a tube amp sound could not be reached however in its wider spectrum. Still the transistor amps had some advantages over tube amps: They sounded very compact and linear, were less prone to feedback and offered a relatively balanced frequency spectrum and a nice sustain, which was the ideal sound of many jazz guitarists. A Gibson L5 played through a LAB or a Polytone is completely convincing – even today.

One disadvantage that the transistor amps had in particularly was its dynamic behaviour, in their relatively poor response and in their tendency to not let the individual character of a particular guitar fully unfold. You could also say: Transistor amps tend to standardise tone.

I do not wish to start a discussion about tube versus transistor because transistor amplifiers will continue to play a rightful role in jazz. It is more about ways to show how one can get the typical warm jazz tone with a tube amp without all the disadvantages.

Above all I am thinking of the sounds of the early sixties, which were marked by numerous jazz guitarists including: Wes Montgomery, Kenny Burrell, the early George Benson, Herb Ellis, Joe Pass, Barney Kessel, Grant Green and Jim Hall. All of these guitarists were playing tube amps on their early recordings and getting fantastic sounds. Today tube amps are celebrating a renaissance with jazz guitarists.

Let us first take look at the most popular models from the distant past. In the fifties the combos from Fender (Tweed), Gibson, Standel or Flot-A-Tone were especially loved by jazz musicians due to their sound and their small size. These amplifiers were sufficient for jazz guitarists because they were usually accompanying musicians and they performed as a soloist only in rare cases. They often stayed in the background and did not play very loud.

Even back then, most jazz guitars were equipped with a tone control that made it possible to filter out unwanted peaks and thus to form the typical dark jazz sound. But soon the guitar became a solo instrument. Just think of the impressive sound of a cascading Les Paul, who at that time had good reason to play on a solid body. The traditional jazz players remained with their hollow bodies and now had to fight against all the disadvantages of the electrification of their sounds. Recently I read in a retrospective of Wes Montgomery that he alleged that during his entire career he was unhappy with his sound because he simply could not find the perfect amp. One might even go so far and assume that the dark jazz sound is actually created only (and eventually cultivated) because the amount of unpleasant highs tube amplifiers have, are rather imperfect sounding and also quickly led to feedback. Most guitarists wanted more of a linear and natural reproduction of their beautiful instruments that already sounded great acoustically.

Let’s now take a look in the interior of a tube amp and consider certain circuit characteristics which can be modified for a better jazz tone. The objectives of these measures are the reduction of distortion and the high frequencies, improving the mid-range and increasing the linearity of the sound.

First, a list of known suitable amplifiers for conversion to a “jazz box”: Fender Tweed Fender amps from 1956 and Brownface, Blackface and Silverface combos. Examples from this list shall be explored in following issues.

Let’s start with a Tweed Deluxe amp replica from Cream which I have converted for jazz sounds. These amps are known for their distortion when left stock and therefore not ideal for a clear jazz tone. But they are very small and handy and with around 15 watts of power ideal for use in a club. In addition, these amplifiers are connected with a so-called “split-load” phase inverter which is appropriate for our purposes because of its low gain. The only drawback is the two coupled volume pots, which restrict the volume control range on the one hand and deliver too much gain in the preamp. The aim is to reduce the gain in the preamp and increase the output power and stability of the amplifier. Only then we get enough headroom for a clear sound.

Just this once, I should like to “put the cart before the horse” because there are a number of measures to improve the amp without intervention on the circuit.

First, these amplifiers usually have an inefficient speaker. Powerful speakers with a good efficiency rating are especially suitable for jazz sounds. Those who love the Alnico sound can search out an old JBL D-120 and replace the aluminum dust cap with a counterpart out of fabric (available from Weber VST). The speaker can be helped dramatically in the highs and we get a warmer, rounder tone. Excellent was also the old Fane Crescendo Heavy-duty speaker, which is also suitable after the removal of the aluminum dome making a perfectly clear and powerful sound. These speakers were also used by David Gilmour. Another excellent choice is also an Electro-Voice 12L or a Jensen C12K with 100 watts. All these speakers better the sound of the Tweed Deluxe significantly. You only have to watch out for the thin baffle-board because vibration during transport could for example pull heavy speakers from the screw holes.

A further stabilizing method is the conversion of the power tubes to 6L6 or 5881, which I recommended at this point several times. Although the amp has only about one or two watts more output, the increase in headroom is very clear. You get more clean reserves and dynamics. Here I recommend changing the cathode resistor of the amplifier from 250 (typically with 5 watts) to 330 ohms with 10 watts. If you play a jazz guitar with humbuckers, we recommend the low input of the normal channels. Here there are less highs and the output signal of the guitar is more attenuated. It should be noted that the volume pots affect each other on the Tweed Deluxe. By turning the unused channel by not more than 70 percent, the tone is much cleaner, but also quieter.

If you don’t wish to utilize this trick, you can simply remove the cathode of the second stage capacitor (Elko 25mF/25 volts) and reduce the gain of this stage substantially, which in turn increases headroom. The amp will be clearer and somewhat linear, but also a touch softer.

Even more clear sound can be obtained by replacing the output transformer. Something I always do in such tuning. In this case I choose a Mercury Magnetics Tweed Pro Axiom FTPRO-O transformer (available at Tonehenge Amplification) with 8 ohms, which gives much more stability to a small tweed amp.

If you want to use the amp only for jazz, you can also decouple the two volume controls from each other and only one channel and a tone control remain. Now you can adjust the volume much finer and linear. The circuit can be found at www.schematicheaven.com under Fender Deluxe 6G3. Here the channels are completely separate, each with their own volume and tone control. It’s only after the volume knobs on the channels that two 220k ohm mixing resistors are mixed together again.

Since the Tweed Deluxe played with humbuckers has in general somewhat bassy sounds, I also reduce the value of the coupling capacitors from 0.1mF to 0022mF. This makes the sound tighter and more mids. Sprague “Orange Drop” P715-type fit perfectly here.

Finally we get to fine-tuning via preamp tube placement. With a good 12AY7 and a 12AX7 of your choice, you can continue to shape your favourite tone. For those of you who have not had enough, you can play with the value of the capacitor on the tone-pot. The Deluxe was originally installed with a 0005 UF capacitor but also possible are values such as 0.01mF or 0.02mF (as in the 6G3) for a slightly warmer tone. If you want to darken the sound one can bridge one of the anode resistors at the 12AY7 with a 0.003mF capacitor (as in the normal channel of the Brown Vibrolux).

The result is a truly compelling jazz amp for small clubs, feeds back less, offers more clean reserves and could compete with any Polytone but all the benefits of dynamic and harmonically rich tube sound can be enjoyed. Diana Krall’s guitarist Anthony Wilson often used a Tweed Deluxe replica from Clark and his blond Gibson Byrdland in the studio. This sound is very reminiscent of Kenny Burrell and offers a wonderfully unique character. Have fun experimenting!

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Article: Let’s Ask Budda with Jeff Bober of Budda Amps

Q: I’ve got an SR Blackface ’66 amp, all original. The sound is very thin, weak and trebly. There’s nothing wrong with any of the tubes, and it has been biased correctly. I’ve tried the amp through different speakers but found the same result. The amp hasn’t been played very much over the years. Can it be old, dried-out capacitors that make the amp sound like this? Can a complete replacement of the capacitors really improve the sound – meaning to give it more twang and bottom end, or “life”? – Tobbe Sweden

A: Beautiful amp. One of my favorites… except, of course, for a Budda!

I’m assuming both channels of the amp are thin and weak. If it were only one channel that sounded bad, I would tell you that the 100K resistor in the tone stack of that channel was probably open. This would also disable the Middle and Bass control, but I’m going to assume that all the amplifier controls function properly. Since you also mentioned that the amp has been properly biased, I have to assume that the primary sections of the power supply have the correct voltages.

Considering the amp’s age and the possibility that it might have been sitting idle for some time, a power-supply cap job is probably a good idea. This might not be the source of the problem, but once any other repairs have been made it will make the amp sound stronger and tighter. Make sure the values of the power-supply resistors are checked after the filter caps have been removed. A power-supply resistor that’s substantially out of tolerance can cause degradation in tone, but usually it won’t be as drastic as the symptoms you’re describing. And don’t forget to have the bias supply cap replaced. A weak cap in the bias supply will give the amp some additional unnecessary hum. You might also want your tech to do some normal maintenance on the amp, such as cleaning all of the tube sockets and controls while he’s in there. A very dirty tube socket, especially in the phase inverter, can really suck the life out of the amp. If the amp still isn’t right after the maintenance and power-supply build, it’s time to start looking elsewhere.

Okay, let’s look at some other possible causes for an anemic Fender amp. The first thing I’d look for would be the ground connections from the circuit board. These are the buss wires that come off the circuit board behind the controls and solder to the brass grounding plate that runs under the control panel. I’d check all of these connections, but there’s a particular one that seems to be the most frequent offender. It comes off the board in the area of the tremolo and phase inverter circuits behind the tone controls for Channel 2. For some reason this solder connection tends to break, causing the phase inverter to lose its grounding. That makes the amp lose substantial power and sound thin. If any of these ground connections is broken, it takes a good deal of heat to re-solder them. So, you’ll need to use a high-wattage soldering iron or gun. If all these ground are intact, the next thing to check would be the 100-ohm (brown/black/brown) resistor in this same area. It’s the only resistor in the area that is positioned horizontally on the circuit board. It also typically suffers from a broken solder connection and will yield the same low-power situation. Re-solder the resistor, and you should be good to go. If not, it’s time to start looking at the other major cause: a bad output transformer.

The best way to determine if the output transformer is bad is to simply substitute it with one you know is okay. A good way to check it is to simply unsolder the leads coming from the original transformer and attach a replacement using clip leads. If you can’t come up with a Super Reverb transformer to try, a Twin Reverbtransformer will work well for the test. If you need a replacement transformer, I have to recommend (as I have in the past) Mercury Magnetics. Their Axiom line of transformers should have just what you need. They can be found at www.MercuryMagnetics.com.

I hope you can make your Super super again.

Source: https://mercurymagnetics.com/pages/news/PremierGuitar/MusiciansHotline-2.htm

The newest family of transformer designs from Mercury. APS transformers are built and specifically optimized for today’s amps and today’s tubes. Due to power, modern tube production, design and chassis “real estate” limitations, not all modern amps can be modified or upgraded to handle the full-on affects of our Axiom, ToneClone, Radiospares or Partridge transformers. APS transformers correct many of the design limitations of the stock transformers to give you the most your amp can offer. APS transformers make your amp more reliable and better sounding. If you depend on your modern amps for a living, then you need the peace of mind APS transformers will give you. Transformers made to take the punishment of being on the road and keeping your amp running.

All APS transformers come with our Automatic Thermal Resettable Fuses. Ask your Mercury Sales Rep about this important new feature! All APS transformers come with both our 10-year Workmanship Warranty. APS transformers may be used for upgrades or replacements for modern tube-based guitar amp applications.

To find out more, or discuss to the characteristics of the different transformers sets available for your amps, give us a call or email.

As you would expect, Mercury also produces high-end transformers for hi-fi. Whether you are building, restoring or repairing you’ll want to talk to us about obtaining the best possible sound-quality and performance from your system. In addition to ToneClone and Axiom brand variations, Mercury’s M.A.G.I.C. series represent the epitome of transformer technology for hi-fi amps. For the consummate audiophile M.A.G.I.C. are the ultimate in high fidelity transformer designs. Mercury also OEMs transformers for many of the most award-winning hi-fi amps available.

Requests for educational consumer handouts about Mercury have been pouring in. So, we’ve designed this simple P.O.P. (point-of-purchase) display to make information on Mercury’s quality transformers available. The brochure discusses transformer upgrades and restorations, as well as our ToneClone, Axiom and Radiospares lines of vintage and next-generation products. A must-read for any guitar player!

Help your customers to learn more about the sonic-qualities of great transformer designs. Our eye-catching display is designed to hold 40 Mercury Magnetics “Unleash Your Amp’s Tone!” brochures.

Truly inspirational and superior tone has led you to the final link in the chain – Mercury Magnetics. Premium guitar amplifier power transformers, output transformers and chokes.

100% American made — no hidden imports — we really do make ’em from scratch, right here in California!

100% handmade and hand-tuned using only hand-wound components. We never compromise or play bean-counter games by short-cutting, attrition or using cheaper materials. Each and every transformer is consistent. If you ever need to replace one of our transformers, your amp won’t lose its tone — your replacement will sound exactly the same as the original.

American-made steel — we’re the only transformer manufacturer who custom orders, from an American steel mill, the unique alloys used in our transformers. These alloys are not only made here in the USA to military specifications, they are not available anywhere else in the world. They’re the same alloys used in the all-time best-sounding transformers during the “sweet spot” era (pre-1965) of guitar amplification history.

Things are never stagnant around here. Mercury maintains active and ongoing R&D (research & development). All kinds of new and exciting-sounding transformer designs (Axiom series), as well as our ongoing cloning of outstanding output transformers mined from the great old amps (ToneClone series). For vintage British amp freaks, check out our Radiospares, Hiwatt and Partridge series. And many modern amps can be upgraded with our APS series — our newest line of guitar amp-specific output transformers.

For any popular amp design we’re likely to have not just one but several transformers for different purposes and different tonal characteristics. It’s always a smart idea to discuss replacement, restoration or upgrading with your Mercury rep. — you’ll find his input invaluable.

Our output transformers are found in the amps of virtually every major player in the world. Many specify Mercury and won’t play an amp without them.

Mercury transformers are standard components or factory upgrades available in virtually all high-end boutique amps, including Fender’s boutique and custom shop lines.

Mercury transformers are so highly rated that they typically increase the value of any amplifier they’re installed in.

Mercury’s Exclusive Tonal Satisfaction Guarantee:

Your complete tonal satisfaction is our only goal. All Mercury Magnetics® APS®, Axiom®, ToneClone®, and Radiospares® products come with a Tonal Satisfaction Guarantee. If you are not satisfied with any Mercury Magnetics® transformer or choke, for any reason, you may return it within 30 days for an exchange or refund (minus all freight). See “Exchange or Refund Policies” below for addendums.

Mercury’s Limited Workmanship Warranty Policy:

Mercury Magnetics® warrants its non-OEM transformers to be free from defects in material and workmanship, if properly installed, under normal use for a period of TEN (10) YEARS from the date of purchase, and by the original owner. Note: this warranty does not cover damage caused by external sources or user error. Defective transformers will be replaced or repaired at our discretion. To the extent permitted by law, the foregoing is exclusive and in lieu of all other warranties or representations whether expressed or implied, including any implied warranty of merchantability or fitness. In no event shall Mercury Magnetics® be liable for special or consequential damages. All warranty returns are examined by our engineering staff to determine the exact cause of failure. This warranty is void if your transformer has been tampered with. See “Exchange or Refund Policies” below for addendums.

Shipping Info:

• All shipments are F.O.B. Chatsworth, CA

Exchange and Refund Policies:

• For warranty inquiries on Mercury-made OEM transformers, please contact the manufacturer.
• Please contact Mercury Magnetics® to discuss making an exchange or to obtain a refund within the thirty (30) day guarantee.
• Insure your shipment for the invoice amount.
• Include the original or a copy of the invoice.
• All transformers must have their identity stickers intact.
• CODs will not be accepted. Ship prepaid. If the product is found to be defective or in the case of a shipping error, we will issue you a refund for shipping costs.
• Keep a record of your shipment until you receive your credit or replacement.
• Returns or exchanges are accepted within a 30 day grace period.
• Custom Shop orders or Mercury Vintage (restorations and/or rewinds) are covered by the Workmanship Warranty but not our Tonal Guarantee.
• Wrong parts sent to you due to errors on our part will be replaced or credited at your option. Return freight for that product will also be credited.
• Do not cut the lead wires until you have tested and listened to the installation. Before cutting the leads, solder and bolt the transformers in, and try them out. When you are satisfied, cut the leads and complete the installation. Cut leads to the transformer will incur a 20% restocking fee. For a refund the product must be returned in salable condition without damage or cut lead wires.
• Transformers that have been tampered with, modified, or with unauthorized attempted repairs will be rejected. Please package all product carefully.
• No credit will be issued for less than $5.00US.
• The use of any type of attenuation device on any Mercury Magnetics transformer will void the 10-Year Warranty. Using “dummy load” or “power attenuators” damages transformers. These type of products wear out power tubes at an accelerated rate, and in some cases may cause RF to be generated in the output, which may destroy the output transformer.
• Discontinued, obsolete or closeout sale items will not be accepted for return unless they qualify under our warranty.
• The Mercury Tonal Satisfaction Guarantee and 10-Year Warranty is only extended to transformers and chokes of our upgrade kits. Mercury assumes no responsibility or liability for the amp or the work done to the amplifier.

All Mercury Magnetics® products are 100% handmade in California, USA.

Copyright © 1954-2018 by Mercury Magnetics. All Rights Reserved. Mercury Magnetics, Mercury Vintage, Partridge, FatStack, SuperStack, NewVolt, Mini-Choke, Multi-Choke, Mercury Custom Shop, Mercury Boutique, “The Heart & Soul of Your Amp,” “Holy Terror,” “Bad Guitar Tone — Whatever Its Evil Mission It Must Be Stopped!”, “Champ 600 Upgrade,” “XLG Upgrade Kit,” “Mean 13” and “The original British amp tone — shaken, but not stirred,” “Our Transformers are Stacked,” “The Essential Building Blocks of Your Tone,” “Mercury Studio-Pro Upgrade Kit for the VOX AC4tv,” UTM (Universal Transformer Mount), Amp-Saver and Copper-Tone are trademarks licensed to Mercury Magnetics. Axiom, ToneClone, Radiospares, VoodooScrew, Multiple Arrayed Geometric Inductive Coupling (M.A.G.I.C.), and APS (American Pro Series) are registered trademarks licensed to Mercury Magnetics. All other companies, products and trademarks mentioned on this website are trademarks of their respective owners. Unless otherwise noted Mercury Magnetics is not affiliated with any of these companies.

Mercury Mod and Upgrade projects and their documentation are the result of technical investigations made by the engineering staff of Mercury Magnetics. The disclosure of the information herein may pertain to proprietary rights, and the furnishing of these documents does not constitute an expressed or implied license to use such materials.

Mercury Magnetics® transformers and other products are in compliance with the European Union RoHS Directive 2020/95/EC with respect to the following substances: lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CR (VI)), polybrominated biphenyls (PBB), and polybrominated diphenyl ethers (PBDE).

Mercury Magnetics® founded in Southern California in 1954 and incorporated in 1968.

CAUTION!

The voltages in your amplifier can be dangerous. Transformers and chokes are not user serviceable parts. Installation of these components should always be performed by an experienced technician.

The simple ability to use a soldering iron is not enough to qualify a “do it yourself person.” Those who are inexperienced in working with electronic circuits should never attempt to service their amplifier. Household line currents can be deadly!! Transformers, chokes and large filter capacitors can store a dangerous charge for several days or more after the amplifier has been unplugged. Never touch the terminals of such devices without being certain of their charge status. Risk of shock and damage to equipment may result from mishandling and/or improper use of these components. Please use common sense and always think safety first. After all, tone is most enjoyed when you are alive to hear it.

3 Henry Mini-Choke — DCR = 92Ω — tolerance +/-10%

Upgrade!

Supro Super

4100 — Drop-in Upgrade!

30th Anniversary 6100 — Drop-in Upgrade!

For the 1959 Hand-Wired reissue amp — 2 Henry value

Bolt hole spacing is 2 13/16″ center to center

(For a 3 Henry choke use the MAR100-C)

JCM2000 — 3H — 250mA — add this choke to your 100 Watt JCM2000 for improved tonal richness

TSL60 — 3H — 250mA — add this choke to your TSL60 for improved tonal richness

100 Watt JCM2000 — Dagnall D2105 (TXMA 00061)- SuperStack (over 4″ of Iron!)

** 5 1/2″ tall, for head amp cabinets only (no combos) — Bolt hole spacing is 2 1/2″ x 3 1/8″

TSL60 — Upgrade!

DSL201 — 9H — add this choke to your DSL201 for improved tonal richness

9 Henry Mini-Choke — add this choke to your amp for improved tonal richness

9 Henry Mini-Choke — add this choke to your amp for improved tonal richness

Dark Terror – Single 120V primary — Drop-in Upgrade!

Upgrade!

9 Henry Mini-Choke

Mercury’s exclusive multi-tap Multi-Choke – Size: Micro
1 Henry (92Ω DCR)
3 Henry (160Ω DCR)
5 Henry (210Ω DCR)
7 Henry (246Ω DCR)
9 Henry (285Ω DCR)

Tweed — 4 Henry. Uses Grain-Oriented Iron

JCM800 Spring Reverb transformer — reverb pan #4DB3C1D

Drop-in Upgrade! Spring Reverb driver Transformer

3 Henry Choke – Upgrade over stock resistor

4 Henry. Uses Grain-Oriented Iron

600Ω Line — 1:1 bifilar windings — like Jensen JT-11-FLCF

Model 1930 — Upgrade!

DSL201 contact us for correct mounting — Upgrade!

10 Henry choke — mid-sized — 2 13/16″ mounting centers — DCR = 210Ω

15 Henry choke

1 Henry Mini-Choke — DCR = 28Ω — tolerance +/-10%

Larger 30 Henry choke

2 & 4 Henry choke — 4 screw mount. Uses Grain-Oriented Iron

6 Henry Mini-Choke

8 Henry Mini-Choke — DCR = 239Ω — tolerance +/-10%

2 amp 6.3V filament transformer with center tap

Mercury’s exclusive multi-tap Multi-Choke — Size: Large
5 Henry (63Ω DCR)
10 Henry (88Ω DCR)
15 Henry (110Ω DCR)
20 Henry (125Ω DCR)
25 Henry (140Ω DCR)

Mercury’s exclusive multi-tap Multi-Choke — Size: Micro
1 Henry (93Ω DCR)
2 Henry (130Ω DCR)
3 Henry (158Ω DCR)
4 Henry (185Ω DCR)
5 Henry (205Ω DCR)

Single ended — 7K primary — 4 & 8Ω taps

Brown — single ended — 8Ω tap

Brown — single ended — 8Ω tap — UL tap

Single ended — 4K primary — 8Ω secondary

Tweed — single 2Ω tap. Uses Grain-Oriented Iron

Sears Silvertone — PT for models 1457 and 1449

Tweed — ’59 — Dual 8 Ohm taps (one optimized at 5K for use with two 6L6s the other optimized at 8K for use with two 6V6s). Uses Grain-Oriented Iron

Mercury’s exclusive multi-tap Multi-Choke — Size: Mini
1 Henry (33Ω DCR)
2 Henry (44Ω DCR)
3 Henry (53Ω DCR)
4 Henry (61Ω DCR)
5 Henry (68Ω DCR)

Custom design — 4, 8 & 16Ω taps

Single ended — 12K primary — 4, 8 & 16Ω taps

Yamaha CS20M Analog Synthesizer Keyboard– Upgrade!

8K primary — 2, 4 & 8Ω taps

25 Henry choke

Single ended — 4K primary — 4Ω secondary

Single ended — 9k primary — 4 & 8Ω taps

Mercury’s exclusive multi-tap Multi-Choke — Size: Large
2 Henry (32Ω DCR)
5 Henry (50Ω DCR)
7 Henry (58Ω DCR)
10 Henry (69Ω DCR)
12 Henry (76Ω DCR)

Mercury’s exclusive multi-tap Multi-Choke — Size: Large
1 Henry (27Ω DCR)
3 Henry (48Ω DCR)
5 Henry (60Ω DCR)
7 Henry (71Ω DCR)
9 Henry (80Ω DCR)

Tapped transformer — for use with 5V or 6.3V tube rectifier — single 120V

Mercury’s exclusive multi-tap Multi-Choke– Size: Large
10 Henry (110Ω DCR)
15 Henry (135Ω DCR)
20 Henry (155Ω DCR)
25 Henry (172Ω DCR)
30 Henry (190Ω DCR)

Single ended — 20k primary — 4Ω tap

Single ended — 20k primary — 4,8 & 16Ω taps

Single ended — 3K, 5K, 7K & 9K primary — 4 & 8Ω taps

Class 5 — single 16Ω tap — Upgrade!

Class 5 Head — 8 & 16Ω taps — Upgrade!

Upgrade! — TXOP 00012 — Bolt hole spacing is 2″ x 2 1/2″

GA-20 — 4, 8 & 16Ω taps — use with EL34s

Class 5 — Universal Voltage Primary — Upgrade!

Early ’70s Specialist — 120V primary — Upgrade! — DE# T 3133

12 amp 6.3V filament transformer with center tap

Dual Terror — 4, 8 & 16Ω taps — Drop-in Upgrade!

Upgrade! — # TXMA – 00081

Early ’70s Specialist — 220V, 230V & 240V primary — Upgrade!

40-50 watt — 5K primary — dual 8Ω secondary — bifilar winding

Single ended — 2.3KΩ primary — 8Ω secondary

AD15 – Drop-in Upgrade!

Custom designed — 25 watt

Custom designed — 25 watt — 220-0-220 unloaded B+

Dual primary — 5200Ω and 6600Ω — 4, 8 & 16Ω taps — Upgrade!

Modern 40 watt

Custom designed — 25 watt — 100V, 120V, 220v & 240V dual primaries

SVT Classic — flat mount with 148V bias winding — please contact us for details before ordering.

Plexi — for KT88 / 6550 (& 6L6) tubes — 5.9 kΩ primary

Vertical mount, bolt hole spacing is 2 1/2″ x 2 1/2″

Reissue version — with leads

Single ended — single 4Ω tap

6K primary

Single ended — single 8Ω tap

5k primary — 4, 8 & 16Ω taps

Large AC15 — 8 & 16Ω taps

Plexi — use in the higher gain amp

Single ended — 3k primary — 4, 8 & 16Ω taps

Single Ended 5k primary — 4, 8 & 16 Ohm Secondary taps

Universal dual primary — 290-0-290 unloaded B+ — 70V bias winding — 7 amp center tap — 6.3V filament winding — 4A-5V winding — 8087 size

Upgrade!

50 watt — 8 & 16Ω taps

25 amp 6.3V filament transformer with center tap

Reissue version — with bias winding

70s era Fender Rhodes Piano/Keyboard 73 — Drop-in Upgrade!

Colossus — ’70s — solid state

Upgrade! — D.E. # TXMA 00080

Flat mount — bolt hole spacing is 2 1/2″ x 3 1/8″

Plexi — 3100Ω primary impedance — 1.5″ stack

Optimized for 6L6 / KT88 / 6550 tubes — 2, 4 & 8Ω taps — 1.5″ stack — Uses Grain-Oriented Iron

Use with higher gain amp — 2, 4, 8 & 16Ω taps

Great for JCM800 and highest gain amps — 1.5″ stack

Optimized for 6L6 / KT88 / 6550 tubes with UL taps– 1.5″ stack

Optimized for 6L6 / KT88 / 6550 tubes — 1.5″ stack. Uses Grain-Oriented Iron

Single 120V primary — tapped B+ — 260-0-260 & 300-0-300 — 6.3V @ 9A — 5V @ 4A — Upgrade!

Optimized for 6L6 / KT88 / 6550 tubes — 2, 4, 8 & 16Ω taps — 1.5″ stack — Uses Grain-Oriented Iron

Haddon — smaller size — lower B+

100/100 — EL34 or 5881 Dual Monoblock power amp PT — Drop-in Upgrade!

Flat mount w/ lugs — 2 1/2″ x 3 1/8″ mounting centers

JTM75 — high B+ — 5V winding

4, 8 & 16Ω taps — 1.75″ stack

’68 Plexi — 375-0-375

Drop-in Upgrade!

360-0-360VAC unloaded B+ — 6.3V CT @ 7A — Added 13V @ 1.5A Accessory Winding — With Universal Voltage Primary

Custom design — 4, 8 & 16Ω taps — 1900Ω primary

High Power Tweed Twin — true balanced center tap on 6.3V filament winding –Uses Grain-Oriented Iron

JVM410 & Silver Jubilee 2555X Head — Dagnall TXOP-00029 (D5118 TRX)

Check your mounting hole spacing! — Bolt spacing is 3″ x 3 3/4″

JCM2000 TSL 122 Combo amps –Dagnall TXMA 00061 (D2105) — 3″ lamination stack

Bolt hole spacing is 2 1/2″ x 3 1/8″ — can be used in JCM 2000 head amps

JCM900 — Drop-in Upgrade!

Vintage Modern 100W — Upgrade! For use with four 6L6/5881/KT66/6550/KT88 type tubes

Custom design for bass guitar application — 4, 8 & 16Ω taps — 5000Ω primary

1.7kΩ primary, 4, 8 & 16Ω taps — 2″ stack M6 laminations

Bolt hole spacing is 3″ x 3″ — *fat stack version of O100JM

The Mean 13 High-Power Upgrade requires a radical modification of the Little Giant’s circuit board and chassis — including the addition of twin-6V6 sockets and its full-custom transformers and choke.

Everything you need to transform your Little Giant head (BH5H) or combo (BH5-112) into a 13 Watt monster. Mercury’s kit includes detailed step-by-step, full color illustrations, schematics and photographs to help guide you through the process (tubes not included).

For our other Blackheart Little Giant Kit, see our XLG kit.

Available in 120V only. At this time export versions are not available. Amplifier not included.

JCM900 — Drop-in Upgrade!

4 & 8Ω taps — 2500Ω primary — 2.5″ stack — UL taps

4, 8 & 16Ω taps — 2.5″ stack — 3K primary

Oversized Plexi-style — 2000Ω primary impedance — 4, 8 & 16Ω taps — Uses Grain-Oriented Iron

Drop-in Upgrade!

Drop-in Upgrade! — For modern era Orange amps, not vintage ones

Contact us for more details if needed

JVM410 & Silver Jubilee 2555X Head — DE #TXMA-00121 –Universal Voltage Primary

*Check mount dimensions! — Ours is 3″ x 3 3/4″ — the JVM410 & 2555X has metric spacing dimensions!

’70s Model T — #28-2603 –Dual primary windings

Flat mount style — bolt hole spacing is 3″ x 3 3/4″

3″ stack — lower B+ — 385-0-385

Vintage Modern — Universal Voltage Primary — Upgrade!

Custom design for bass guitar applications — 2, 4 & 8Ω taps — 1500Ω primary — 3″ stack of iron. Uses Grain-Oriented Iron

DSL/TSL — Dagnall D2105 & T-5826 (TXMA 00061) — SuperStack (over 4 inches of iron!)

Sits 5 1/2″ tall in head amp cabinets only (no combos) — Bolt hole spacing is 2 1/2″ x 3 1/8″

Vintage Modern — Upgrade!

9005 50/50 — Rack mount power amp — #1204-314 — Upgrade!

60 watt — 2 x 6L6 — 4, 8 & 16Ω taps & UL taps — Upgrade!

JCM800 — Model 2001 — 375 bass amp

Drop-in Upgrade!

1959 Hand-Wired reissue — 1.5″ stack — Drop-in Upgrade!

*Replacement for TXOP 00021  (C 1998)

4100 — Drop-in Upgrade!

2.6, 8 & 16 Ohm taps — flat mount — Upgrade!

Vintage Modern 50W — Upgrade! Use with two EL34/KT77 type tubes

Vintage Modern 50W — Upgrade! Use with two 6L6/5881/KT66/6550/KT88 type tubes

JCM600 — Upgrade!

JVM410 Head — Check out the JVM Forum! — Upgrade! — Use with four 6L6/5881/KT66/6550/KT88 type tubes

Vintage Modern 100W — Upgrade! — Use with four EL34/KT77 type tubes

50 Watt Combo (or Head) — Drop-in Upgrade! — TXOP 00030 (D5240)

Flat mount w/ lugs — Bolt hole spacing is 2 1/2″ x 3 1/8″

JVM215C Combo — Drop-in Upgrade!

1700 Ohm primary — 4, 8 & 16 Ohm taps. Uses Grain-Oriented Iron

JCM 2000 TSL601 — Upgrade!

JCM 2000 TSL602 — Upgrade!

JCM 2000 TSL60 — Upgrade!

6L6 / KT88 / 6550 tubes — 1.5″ stack

12K primary — single 8 Ohm secondary tap

12K primary — single 8 Ohm secondary tap

Custom design — Large 4, 8 & 16 Ohm taps — 6K primary. Contact us for mounting options

16K primary — 4, 8 & 16 Ohm secondary taps

GA-8T — single 8 Ohm tap

15 watt — 8K primary — single 8 Ohm tap — Upgrade!

Larger — single 8 Ohm tap — Horizontal A-Frame mount

Larger — 4, 8 & 16 Ohm taps

30 watt — VC30 with single 12″ speaker — 4 & 8 Ohm taps — Upgrade!

Framus Cobra 100 watt — Upgrade!

15 watt — 4, 8 & 16 Ohm taps — Upgrade!

20 watt — 4, 8 & 16 Ohm taps — Upgrade!

60s — Upgrade!

SVT — Small footprint version

Single ended — 9k primary — Single 4 Ohm tap

Single ended — 9k primary — 4, 8 & 16 Ohm taps

Push/pull – 8 Ohm primary — single 8 Ohm tap

4, 8 & 16 Ohm taps — 8k primary — Massive 1-1/4″ stack!

AD200 BASS MK3 — 2, 4 & 8 Ohm taps — Drop-in Upgrade! –Uses Grain-Oriented Iron

40-50 watt — 10K primary — dual 16 Ohm secondary — bifilar winding

Thunder 30 — 4.2 kΩ primary, with 4, 8 & 16 Ohm taps

Bolt hole spacing is 2″ x 2 3/4″ — Also used in Dark Terror amps

Drop-in Upgrade!

Dark Terror – 8 & 16 Ohm taps — Drop-in Upgrade!

Single ended — 8k primary — single 16 Ohm secondary

Single ended — 8k primary — 8 Ohm tap

Single ended — 4 Ohm tap

2.5k primary — 2, 4 & 8 Ohm taps

Single ended — 3.5k primary — 2 & 4 Ohm taps

Single ended — 4K primary — 8 Ohm secondary — larger stack than the SE-4K

Single ended — 9k primary — single 16 Ohm tap

50W — 5.2K and 2.8K Dual Primary– 4, 8 & 16 Ohm taps

8 & 16 Ohm taps — Drop-in Upgrade!

100 watt

Drop in Upgrade! Single 16 Ohm Secondary

Drop in upgrade! Single 120V Primary

Drop in upgrade! With Universal Voltage Primary

Drop in Upgrade! Single 16 Ohm Secondary

Single Ended — 6K primary — Single 8 Ohm Secondary

Single Ended — 8K Primary — 4, 8 and 16 Ohm Secondary

Approx 460VDC B+ — Added 15V and 100VCT Accessory windings

Improved version vs. stock — Contact us for Valve Jr. Upgrade instructions

Single 4 Ohm Secondary — Contact us for Valve Jr. Upgrade instructions

4, 8 and 16 Ohm Secondary — Contact us for Valve Jr. Upgrade instructions

Upgrade! Single 4 Ohm Secondary

Upgrade! 4, 8 and 16 Ohm Secondary

Add this choke to your Valve Special for improved tonal richness — Upgrade over the stock resistor

Mini Multi Choke with 1, 3, 5, 7 and 9 Henry taps — 2-3/8″ Mounting Centers