Where did you get the idea to start an amp company?
It was the K&F that got me started. Working at Fender and knowing the entire lineage, including the K&F era, which is kind of separate, it was really intriguing to see what kind of things he came up with. Because it was so rare, the K&F was really appealing to me.
How did you discover this cool original gear while at Fender?
People would come in with things that were not in regular production and would want to have things done and have items reproduced, and people would come in for repairs too. It was a nice influx of cool equipment coming in, and we would turn around and reproduce it to the best of our ability. One of the first pieces we did while I was there was the “snake-head” Tele set, the first regular Fender-style guitar that Leo built.
Doesn’t that predate the Nocaster?
Yes, in fact I think that guitar was a ’47 or ’48. It had a four-piece pine Telecaster-style body, two inches thick with a small, black Bakelite pickguard, volume and tone control, and one bridge pickup. The snake-head headstock was the style he was using on his K&F lap steels, so it had three-on-aside tuners, with a solid, fat, maple neck with no truss rod — he hadn’t thought about a truss rod yet! They only made a few of them, and they were made as a set with the woody Pro amp.
So, did you put truss rods in the reproductions?
No, but they are big, round, C-shaped necks, and they’re quarter sawn, so they don’t move around too much.
There are actually guys who believe that necks without truss rods sound better.
This guitar is really neat-sounding because we used antique pine. One of my first jobs there was to rough-cut these old pine boards, glue them up, and plug and fill nail holes. Looking at these old-style guitars and amplifiers in comparison to what was being manufactured at the time, I saw a night and day difference. These have a style to them that nobody does any more.
This got me started thinking about K&F. If the circuit for the woody Pro was primitive, then the K&F amp circuit was even more so. The Pro had 6L6s and a push-pull output, and a 15″ speaker — a field coil speaker, which we had a lot of problems with. The K&F amps didn’t use field-coils and were permanent-magnet.
Give us a little background on K&F.
It was Doc Kauffman and Leo Fender. The information on K&F varies, so I can’t give a perfect history. They started around late 1944, and ran probably to the end of ’45 or early ’46, then they stopped making these in mid-1946. Leo had done some really interesting things — he had designed an automatic jukebox and little P.A. systems, and he was working with his radio company. Then, he had an idea for these guitars. He started making them and it became popular enough that he needed a larger investment; Doc didn’t think he could invest in something that looked like a hillbilly guitar, and at that time, that was the type of music played on them.
I remember even up until the 1960s, many jazz guitarists looked down their noses at these and told us, “When you grow up, you’ll get a real guitar,” meaning something more traditional, like a Gibson archtop.
Yeah, so Doc left and the K&F company was dissolved. Finding pieces from that time period is hard because there’s no record of how many were made and there were no advertisements for them. I do have some pictures from George Fullerton that Doc’s son gave him of the first piece that they put together, which is nothing like the ones that went into production. It’s very beautiful.
Did you get to play that original Tele that was copied for this run of instruments?
Oh, no. The story behind that guitar was that Leo was a huge stickler for not keeping prototypes around. There were two of those — the first one was cut up and the second was thrown in the trash. George pulled it out of the trash. He was young and had just started working with the company; he was a guitar player and this was his creation too! He and Leo went to little bars and shows and listened to players. Without telling them what they were up to, they asked the players what they would want in a guitar, which became the basis for their business and designs: being able to change small parts out easily and being able to easily change the neck on a guitar. There was a bit of a stigma attached to their early instruments because they weren’t craftsman pieces — they were functional instruments.
Yes, they were outside the instrument crafting tradition. This was a modernist piece of design, rather than following classical instrument-building traditions.
Exactly. So when I started researching all the K&Fs, I talked to George who was there just after Doc left, and I got as much information as I could from the closest source. Strangely, though they made guitars and amps in sets, many of the guitars still exist while most of the amps do not. I figure that the guitar is a functional piece and all you have to do is change the strings, but if you have an amp go out, it might have been easier to just go buy another amp.
Was it through the process of reproducing old gear, and speaking with George Fullerton, that you became interested in the 1940s K&F amp?
Yes, that amplifier in particular because it was so simple and because the circuit was kind of the predecessor to the Princeton, but instead of having an 8″ speaker like a Princeton, it had a big, large-magnet, alnico 20-30 watt 10″ speaker. This was late ’44 or early ’45, and these amplifiers were made from military surplus parts, so they were all different and had this unique industrial look about them. Design-wise, it wasn’t made to be the prettiest thing out there — it was made to be functional.
So it was just “The K&F Amplifier” and they only made the one model?
No, see that’s the thing, they made one, and we know the record shows from Doc’s writing on the pictures I have, that the first one they made was beautiful! It had wooden sides, a grille cloth that was embroidered with K&F on the front, and a 15″ speaker. The photo says, This is the first K&F [lap] steel, and this is the first amplifier in the U.S. with a hanging chassis and hanging tubes.” Before that, everything was put on the bottom of the amplifier and the tubes all sat up.
And that amp is gone now?
Yeah, in John Sprung’s book, Fender Amps: The First Fifty Years, he wrote that this amp was made as a custom, one-off piece, and it is likely gone now, since the only pictures we have ever seen of it were the from the 1940s.
That would be a fun one to reproduce, wouldn’t it?
Oh, it would be amazing. There was an article in the October 1998 issue of Guitar Player with a 15″ K&F — the style of the K&F that I am reproducing. It was the same cabinet shape, just larger, and it is the only time I have seen a 15 other than that one custom one-off piece.
So what you had was three or four amps, all without names or model numbers which were essentially prototypes
Yes, they were “if this works we will make another just like it” sort of deals. There were two basic models that you see in published pictures. One is the 8″model that looked like a little lunch box. It had one volume knob and one or two inputs, no pilot light, no fuse, and the cord coming straight out — that was it.
The other is the 10″ model, which is the one I’m reproducing. It had two inputs, no fuse, no pilot light, one tone control, and either one or two volume controls, and two channels — which was something completely new. Each channel ran on one half of the input tube, which is what Fender did until the Blackface era in the ’60s.
It’s not a large amp at only 5-6 watts. The speaker was an unknown Jensen model that had a large, plug-style alnico magnet instead of the horseshoe magnet. I am sure every example varied because the parts all varied — the knobs, transformers, everything. The transformer on the one I am reproducing was a replacement transformer right out of an Allied catalogue made by some unknown manufacturer.
How did you originally come in contact with the amp you decided to reproduce?
I worked with Geoff Fullerton at Fender, who became a good friend of mine. Geoff is George’s son, and was Leo’s personal assistant at G&L for several years. He was a builder and engineer there as well. George’s father used to work at Fender in the wood mill where he ran this huge ripsaw, which George, Geoff and I also ran, so I had become good friends with the family.
George is a wealth of information and a really interesting man to talk to. He has great ideas about how things were done, the reason things were done, and craftsmanship. Even though his guitars were not traditional, the craftsmanship that went into them was impressive. They case-hardened every single one of the screws that went into a guitar, so if you had to repair it, you wouldn’t strip out the threads. Nobody does that kind of thing anymore because it is not cost-effective.
When I talked to George about the amp, he told me about one at the Fullerton Museum owned by Phyllis Fender, Leo’s widow. As he described the amp to me, I decided I wanted to take a look at it. Phyllis said sure, so they pulled it out of the museum for a day. I looked at it, taking every picture and measurement I possibly could. I worked with what I had, but it wasn’t enough to do a reproduction. Later on I was able to go back, and they let me take the chassis down and measure every single component. One thing I couldn’t do was turn it on.
You were able to disassemble this old amp down to the component level?
I was. I took my meters down there and measured everything. Not only did I measure it, but I cross-referenced it to the color code because those resistors and capacitors are 63 years old now and have drifted a lot. One of the things I noticed is that he used many of the components because they were the only things he could get. They weren’t exactly the right value for the position they were in, but he put them in there because they were close enough and that’s what he had.
So, I’m looking at it, and George leans over and says, “You know, you’re the first person who touched the inside of that amp since Leo; you’d better be careful!” Because no one had touched it in all those years, the chassis, being made of steel and zinc plated, was pretty much pure white and powdery — I wasn’t about to leave my fingerprints in it!
Are you going to reproduce the zinc plating and everything?
Oh yeah, but I’m not going to relic it or try to make it look old.
Are there any ground issues getting through the zinc?
Yes, you have to grind away the zinc to get to the steel. And that was one of the things; there’s no circuit board, it’s all point to point, and whatever had to be grounded was run straight to the chassis right there. It was function over form.
What year was the original produced?
I don’t really know if it is one of the earlier or later ones, although I think it is earlier. There is a kind of complex cutaway on the top of the amplifier and a relief on the cord panel that is pretty much decorative. Those two things are also on the 15″ amps that we know were the first ones made. Later examples don’t have either of those features on them, so it is likely an early piece.
Did your experiences at Fender and taking apart the old K&F amp lead to your decision to start an amplifier company?
The K&F thing led directly to my own amplifiers. That amp was amazing and cool, but it was so rudimentary. Boutique amplifiers are becoming a bigger business now and I though it would be interesting to see if I could do my own interpretation of the design.
I was looking at all these beautiful Fender guitars that we were making, the amazing Custom Shop guitars with custom finishes that people wait years for. There are some really nice-looking amplifiers out there, but most of them look like big Tolex suitcases.
It all started me thinking about something that was small enough that you wouldn’t worry about it getting banged around, with the form plus the function, and replicating some of the beauty of the guitar finishes. That really appealed to me – no one was doing that. Finishing it like a guitar, the correct way, is such an art. I wanted to make them so they would match people’s prized instruments.
Over the years, guitars and their finishes have gotten more elaborate, but you aren’t doing that with the new Model 10; it is using simple shape, texture and color for the amplifier, rather than the busy style of many expensive guitars.
I started out spending hours designing cabinets, and the right one just hits you. This one was simple; it effectively gave room for my logo, but with some different elements. I have 1″ radiuses on the corners instead of ¾”, which makes the amp look more spherical, instead of looking like a big square
It gives it a softer, more attractive appearance.
I started the design of the amp with the cabinet, and I got that nice angled swoop to the front, which was simple, not complex — you see some of the amps from the 1940s that had great grilles on them, and some were so complex. Once I got the design for the cabinet down, and I knew that I could physically produce it from a woodworking standpoint, I knew how much space I had, so I could work on the chassis and circuit layout.
Tell me about the Model 10’s circuit and electronic design, and the sounds you were going for.
Well, George introduced me to Bill Sterle who started working at Fender around 1960. Bill is an audio engineer who designed a lot of the original Blackface amps.
Having someone who was there and who designed amps telling me why they made certain decisions is so much different than starting with copies of what Fender, Gibson, or Marshall did. I learned distinction between the amps Bill made and the Fender amps of the 1950s, which were the easiest and simplest designs. The Blackface-era amps were much more complex designs and they were really trying to do different things with the preamps to keep them cleaner.
When Bill was designing things, he stressed that distortion is your enemy — that’s the school of amp design he came from. You have to have the cleanest representation possible. I went to Bill’s house for hours and he would describe everything from tube heater circuit design to what you want to get accomplished in the preamp section, the phase inverter section, and the power section. He told me once you get going on the tone controls, you can go crazy because there are so many variations in tone circuits — not only what you use, but where they are placed.
I wanted to have a 10″ speaker in there. A 10 just has a clarity that you cannot get from an 8″ speaker, and I didn’t want to go as big as a 12. 10s have a really neat sound to them if you find the right one. I knew it was going to be either a small, single-ended design or a cramped, push-pull design. I ended up starting off with a small single-ended design.
So, design wise, you met some of the original guys who developed modern guitar amps, and took it from there, as if you were in that era.
Oh yeah, and every single element that was put in the amp was based on what I was trying to accomplish in the circuit, not based on something I was trying to copy. My initial intention was to make it really straight and clean, without a ton of bells and whistles. It is a single-ended design with a 6V6 power section and a 12AX7 preamp tube.
I looked at a lot of Internet message boards for guys who are building amps, and for players in general, to find out what kind of modifications they were making and what they wanted out of an amp. I tried to keep it really simple and clean, but I did put in a few things that I thought would expand the tone a little more.
Is there a tube rectifier?
No tube rectifier in this. In such a small, single-ended amp that putting one in would be more of a novelty than anything functional. Not putting one in allowed me to use a smaller power transformer and to clean up the power and make it more stable, along with giving me more space to do other things in the chassis. Also, when I went back and talked to Bill Sterle, he threw his hands up and said, “Tube rectifiers are absolutely worthless!” [Laughs]
My impression is that stout, well-built power supplies produce robust tones, especially at high levels. When you are pushing the amp, and you’re not clobbering the power supply, the amp doesn’t freak out as much. If I want a little sag and compression, I use a compressor!
Well, yeah. It’s all relative though, because there is a ratio between the voltage and the current that the plates see. You push harder, sand the plates, and try to draw more current. If the current isn’t there, then there is going to be a difference in the tone.
I started with a solid-state rectifier and that is the only solid-state piece in the amp. In the preamp, I used more of a Blackface preamp design, where I split the 12AX7 in the middle because the amp only has one channel. I do have two inputs on the amp, but one is just hotter than the other.
So there are only two tubes in the amp?
Only two! It’s simple — there is just a treble and a bass control. With all passive tone controls, if you use the control, there is a certain amount of insertion loss, so on bass control I put a switch so you could remove the tone controls from the circuit completely.
The Model 10 has the standard volume, bass and treble controls; then there is the switch. What does it do?
It takes out the negative feedback loop. You turn that off and bypass the tone controls and it will crunch just like an early tweed Champ. Even with only two tubes and three knobs I wanted to be able to have a range so it isn’t just for one style of play; it is an amp that you can play around with and get a cool tone out of.
It has an amazing array of tones for having so few controls.
I have designs of every shape and size, but this is where I wanted to start. In the larger models, I am going to do a 15-20 watt amp, and I may do as much as a 30-35 watt one as well, though I don’t want to come out with a 100 watt monster.
I think people are starting to re-evaluate how much wattage is really needed.
You know, one of the many helpful things I learned from Bill Sterle was how to test everything correctly. Lots of amp makers out there will say, “This is a 5-watt amp,” and that’s what they assume because a similar one was made by Fender, but Fender tested where the wattage comes up just before distortion, on every one, and that’s how we test as well.
The Model 10 puts out almost exactly 5 watts. It has a cathode bias power section and I go through and measure every single one of those tubes and every single output section of each amp to make sure it is right for this design. I don’t want to run these as hot as I possibly can to get every last watt out of them, because it is hard on tubes. I offer NOS tubes as an upgrade, and they are not making any more of them! I run them right in the middle where you get great tone and good longevity.
What tubes have you been using?
Right now I am using Electro-Harmonix preamp tubes and JJ power tubes. I think the JJ 6V6 is a really neat tube. They can handle a lot of plate current, and they sound good.
If somebody wants a Model 10, how long would it take?
I have all of the parts ready to go, but I have a six to eight week lead time on the custom-colored cabinets, including shipping. It takes about four weeks for the paint to be completely finished, because it has to be perfect. It is a guitar finish on the Model 10 and it’s done just like any expensive guitar finish. The amps are built to order, though I may stock certain colors here and there.
It’s exciting to see the founding of a company with such an amazing product. Do you have a price set for the Model 10?
It looks like the Model 10 will be $1050, at least as an initial release price.
You spoke earlier of having several color choices and perhaps some clear finishes on nice wood available.
The cabinets right now are poplar for the solid colors, and ash or alder depending on whether the finish is a blonde or sunburst one, just like a guitar.
If someone asked you what your amp sounds like, what would you say?
Well, what I was trying to achieve was a combination of the tweed Champ and Princeton, combined with a Blackface Champ and Princeton. I wanted to be able to combine all four of those amps together so you could get a really grungy, overdriven, tweed tone or a really clean, clear tone with or without tone controls.
Tell me about the K&F reproduction amp, is that currently in the pipeline?
That amp is 99% done. Because this amp has never been done before, and because the parts are not off-the-shelf parts, everything is different from what is currently available. Everything had to be done from scratch; transformers had to be custom wound, and chassis had to be custom made — and the chassis are not normal dimensions by any means. The tubes are all NOS tubes, because there is no current equivalent to them.
It’s an octal socket preamp tube isn’t it — a large base and pins like a power tube? What tube is that?
It’s a 6SC7 medium mu triode and a 6J5 triode in the preamp section. Each channel gets half of that triode. It’s a pretty low-gain tube actually; it’s not overdriving the preamp circuit a lot like the later 12AX7s often do. There is also a 5Y3 rectifier and a 6V6 output tube. Both input signals merge into a 6J5. Instead of putting one channel with one preamp tube, he made two channels that merged into one preamp tube. There’s one volume control for both channels. The circuit is a lot different than a modern amplifier. Leo was doing it to see if it would be functional, and it was very rudimentary and basic.
The octal preamp tubes give a really unique sound to the amp. They don’t drive it very hard, but it does put out a pretty thunderous crunch when you want. I am keeping it as historically correct as I can, with carbon comp resistors, Mallory 150s as the tone caps, and all cloth-covered wiring, which I don’t do in the Model 10. I am not trying to reproduce a look in the Model 10, but am going for the best possible sound, so I’m using all the best components and wiring by today’s standards.
You selected the components for the Model 10 by listening to them, didn’t you?
Yes, but the K&F is a little different. It’s not wired like you would wire something today; it has series heaters, so you get that hum in there that makes for a unique sound. The only changes I made were necessary for safety. Of course, there is a fuse in this one, along with a 3-prong AC plug. Other than that, it is rudimentary in every way. The tube sockets are spot-welded to the chassis.
Did you actually replicate the spot welds?
Oh yeah! Lots of guys would have riveted the sockets in place, but that was an extra expense, so they spot welded them.
It probably had a terrific ground connection.
It does. I found an original output transformer and power transformer and had Mercury Magnetics reproduce them for me. The speaker was a 10″ Alnico plug-style speaker rated at 40 watts for a 5-watt amp, so it was way over-engineered for the circuit. Most Alnico speakers have a horseshoe shaped magnet, but this one has 2½” donut-shaped magnet. It was also used for higher-end audio and larger-wattage amps. It makes for a really heavy speaker, but it’s really neat. This Weber is the closest to the original speaker that is available.
How much is the K&F reproduction amp going to cost, and when will it be available?
I’m trying so hard to get it finished! I am talking to a paint manufacturer about the wrinkle paint we need, and if that works out we’re in business with getting the K&F out. We should be ready in October at the latest, and the cost will be about $1000.
Playing the Amps
I brought my 1987 hardtail Tom Anderson to Byers‘ shop where I got to play through the first Model 10 off the line and a K&F reproduction prototype. Here is a sample of what I heard:
Model 10
The Model 10 is a beautiful amplifier. If your favorite custom guitar builder built an amp, it would look just like this.
The Model 10 is clear and detailed in the way that only minimal circuit paths can be. Set clean, with the tone controls engaged and the feedback loop in, the highs and lows are well-balanced, the tone circuits do what you wish they would, and the result is a sound that makes you want to play more. Turn off the feedback loop and things get woollier and more tweed-like. Switch off the tone controls and the amp gets a more aggressive, throaty attitude going.
K&F Reproduction
The K&F reproduction amp is totally different from the Model 10 and totally different from almost anything I have ever heard. I can almost hear Charlie Christian playing one and I suspect that today’s players will find musical uses for this tone. The K&F reproduction is very big and a bit wooly-sounding, yet not muffled or dull at all. It gets pretty powerful sounding when you push it hard.
Source: https://mercurymagnetics.com/pages/news/PremierGuitar/PremierG-10.htm
