True-Blue Champ

A few weeks ago I posted about speaker cabinets, materials, and the character that they lend to particular builds. 

I also posted a photo of a 5f1 Champ style cabinet. That amp is still being built, but here are a few teaser shots:

 

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This one’s going to be a stunner.

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What lies beneath…

A circuit’s just a circuit right?

Well, yes and no.

There’s a lot of truth in that, but it can be misleading. In the 50’s and 60’s when Fender, et. al. started cranking out tube amps to accompany those new-fangled electric guitars the work they were doing was largely experimental. And by that I don’t mean to suggest that they were high level theoretical engineers, but rather that there was a lot of trial and error going on. 

Since I already mentioned it, by the time you get to the venerable 5F1 Tweed Champ in 1957, Leo and company had already been through several revisions of the circuit, and were really just trying to get a product to market at a reasonable cost. They tinkered with size, and enclosures, and parts, and in fact they released and scrubbed several interesting designs all within a decade – The Champion 800, the Champion 600, the 5B1, the 5C1 (a personal favorite of mine), and the 5E1.

Part of the equation was the circuit revision. Part of it was the speaker size. But all of that gets wrapped up and stuffed into an under-appreciated box of wood.

And that’s where my focus has been lately. I’ve been interested in what that box does to the sound.

And while we’re here in Tweedsville, there’s no better place to start than the Champ.

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Measuring in at a mere 12″ x 13.5″ x 7.5″ this mighty little critter may seem unassuming, but don’t let that fool you, she has all the right measurements.

Well, almost.

While there’s nothing wrong with 12×13.5×7.5, there’s nothing wrong with adding an inch all around either if it means you can cram a 10″ speaker in there, which is what you see above.

Dimensions aside, what I posted this for is to talk about cabinet making and show those beautiful half-blind dovetails that you’re not going to see when it gets covered up in tolex. Form is important, but above that I believe that amps should function well, and a strong, well made cabinet is part of that equation. Up to now I’ve been constructing my cabinets, regardless of material, with finger joints. Finger joints are as strong as anything out there, and reliable, and there’s nothing wrong with them, but I’m making the move to dovetails. 

But why? You don’t even see them?

Well, my primary reason is that with some new tooling added to my shop, these joints allow me to work quicker and with more precision. They may look more complicated, but I can build a cab in half the time. They also make for a tighter physical joint which may or may not be audible in the resonance of the cab, but I believe will allow me to build a better, more musical product in the long run.

I also want to talk about wood choice. The 5F1 would not be the mythical beast that it is today if it were build out of hickory (fine wood that it is). The pine lets it breathe. It allows it to fill out some of the bass frequencies that might be lost in such a small form factor and it becomes part of the overall sonic signature.

There is no wrong wood as long as it’s structurally capable. There may be better or worse woods for what you’re looking for. Baltic birch makes a sturdy, mid-focused 2×12.” Pine makes a scrappy Tweed Deluxe.I have, (and will again) built a champ out of cherry. It is fantastic and the hard cherry helps give the amp a more focused mid-range bite. 

Lots of ways to slay the dragon, and lots of fun in the process.

 

Does it get any better than a ’65 Princeton Reverb? It certainly gets louder, but does it get better?

That was really the question I was asking myself after I built this beauty:Image

The ’65 Princeton Reverb is the holy grail for many Fender amp aficionados, and why not? It has pristine cleans, but also beautiful overdrive when pushed. And that’s saying nothing about the superb reverb and trem on board. 

The PR is the perfect recording amp, but it can also hang pretty well on most gigs unless you’re playing with a particularly heavy handed drummer. And if that’s the problem, the Princeton sounds so good that you should probably think about replacing your drummer before you replace the amp.

Enough gushing, here are the pics from this build:

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Laying out the inside and running the wires is a breeze inside blackface amps. Not to say that you don’t have to take care to have a good clean layout, but there’s room to work. That’s probably to make up for the hassle of actually mounting the chassis in the combo cab, but even that is an elegant design.

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The power transformer and filter caps locked in. Time to wire the heaters and layout the flying leads from the board. I opted for a raised heater design (a la Victoria amps, et. al.) and I don’t know if it was that design or not, but the amp’s dead quiet at idle, so hooray!

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There are a few mods that deviate from the original ’65 layout and here’s one of them. With the advent of 3 prong wiring the ground switch is no longer needed or functional, so I rewired it as a way to disable the negative feedback of the circuit. 

All I can say about this is WOW! It enhances presence and touch sensitivity in what is an already responsive amp, but it also makes the amp feel and play “bigger.” It broadens the sound and adds a very pleasant harmonic content to the sound. 

Princeton Reverbs also sometimes suffer from a loose and flabby low end. To that end I lowered the values on the coupling caps and tightened everything up. I also paired it with an NOS Eminence Blue Alnico speaker.

This amp is heaven.

 

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The Fourteen31

Most of us have the luxury of living in a world where the overall power of an amp is a secondary concern. Performance venues are less and less reliant on massive backlines and more geared to controlled PA support. If an amp sounds great, stick a mic in on that speaker and run it through FOH. If it’s too loud, mic it off stage.

 

What this means for me is that it’s really all about tone. It is about asking “what is the fundamental character of an amp and how can that be captured and maximized?”

 

After building the 45 I became infatuated by the very different sound of an old off-model Silvertone combo amp – the Silvertone 1431.

This amp is the little brother of the 1432 and a close cousin of the 1482/1484, and because this was a “budget” amp, variants of the same amp were made by valco, airline and all of the other likely suspects. It has the same rough and ready sound that has made these amps the darlings of garage rockers and hipsters, but something caught my ear about the 1431 as unique – almost a chimey “vox-like” quality. 

It’s an odd duck. The original had a 6×5 rectifier, a 6v6gt power tube and a 6au6 preamp tube. The originals came with a 6″ or an 8″ speaker based on surviving examples. 

Silvertones are a study in contradiction. They generally used the cheapest production materials and techniques around, which at times held them back and at other times really contributed to their signature sonic quality. The speaker was a drawback making the 1431 sound thin and weak.  The transformers, on the other hand, while technically “undersized” seem to make the power tube compress and overdrive in a very musical way.

Because of it’s 6au6 pentode preamp, this amp doesn’t have the inherent roaring overdrive of a champ, but it’s far more musical in its cleans with a tone that just loves single coils. Strats and teles sound like heaven through this. P90’s scream.

Just about the time I heard this amp for the first time, I had stumbled upon an old Roberts reel-to-reel unit that was in disrepair, but had some wonderful transformers that would work perfectly for this build. I was able to source the vintage transformers from that unit, and then match them with a collection of new and vintage parts to pull together just about everything I would need for the build.

I ordered a chassis and got to work.  

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Laying out the front panel was nice and easy. I like a clean interface with only the essentials. 

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I wired up the heaters and started planning the layout:Image

I decided on a 6X4 rectifier, which is electronically identical to the 6×5 but was a cool little glass 7 pin tube like the 6au6.

The circuit was all laid out vintage style on tagboard:

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F&T electrolytics, Orange Drops throughout and carbon comp resistors in the signal path. I was really happy with that layout and it makes for a nice quiet ride.

Here’s the Vintage OT all prepped and ready to go:

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After getting the amp up and running, I spent some time tuning the tone control for a wider sweep and more responsive interaction with the overall gain of the amp. I ended up with something very close to the passive tone stack on a fender 5F2A (which has long been one of my favorite amps), built a head cab for it and set about testing different speakers.

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The layout in the head is dead simple and clean. 

The tiny speakers in the original amps made for some “unique” sounds, but really held the amp back in my opinion. This circuit has so much more to give with the proper speaker compliment. 

My first thought was to go with a 10″ Alnico speaker. I have some old stock Eminence Alnico blue 10’s, one of which will never leave my Princeton Reverb, so I tested the amp with one of these in an open back cab. Sounded good, but still missing something. I switched over to a 12″ Mojotone BV25M in an open back cab. I finally decided on a slightly oversized (but shallow) closed back 12″ cab which gives the amp enough bass presence without getting woofy or boomy. It now had everything I liked about the character of the original, but louder and with more authority. The Chime was still there, the harmonic complexity of the 6AU6 was still there, and the 6V6 was able to really fill out and bloom.

The speaker cab is built out of hand finger-jointed pine with a 4 point baffle like an old Fender tweed which gives the speaker the perfect amount of resonance. At 22″ x 22″ It’s slightly smaller than a tweed bassman and lighter than you would expect. 

I couldn’t be happier with how this one came out.

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Ladies and Gents, the Fourteen31.

 

the Forty-Five

the Forty-Five

The great thing about tube amps is that each and every one has a different inherent character that it brings to the party. I’m speaking in sweeping generalities here, but an example of this might be to say that small single-ended amps excel at producing harmonic, musical distortion at manageable sound levels while mid size push-pull amps give you more usable cleans rounding out the sound in a way all their own.

And then there are the big amps, and even bigger amps.

the Forty-Five sits comfortably in the middle of this mix.

It would, in most ways, be true to say this amp is a clone of the revered (and rare) Marshall JTM45. It would be better to say that it’s a tribute combining the sonic signature of the 45 with the Fender 5f6 Tweed Bassman and the JTM 50

For one thing it runs EL34’s in the power section, which is an immediate nod to the JTM 50. Classic JTM 45’s ran 6L6/KT66 power tubes. The GZ34 rectifier tube keeps it solidly in the 45/5F6 camp and gives it the “sag” for which these amps are famous.

A look under the hood shows classic turret board construction with quality components throughout:

All carbon comp resistors where appropriate with metal film where necessary for higher voltages, Sprague, TAD, Mallory and Mojo Dijon caps, you know the works…

My goal in building tube amps is to use the best components for the job as I see it. This doesn’t always mean the rarest or most expensive or the ones with the most “mojo.” It means the best parts for overall function and form. I have no interest in tracking down some rare NOS capacitor because all of the collectors drool over it when a modern production cap will actually perform more reliably and do it at 1/5 the cost.

I didn’t build the head or speaker cab from scratch on this build. Both came from a company named Sourmash Guitar Cabinets. They were great to work with, and have a great selection of custom options. I opted for a blonde look on this one, with black faceplates:

with custom logos from http://www.amplates.com

I’m running the 2×12 cab with Weber Silver Bell Speakers and it sounds phenomenal.

So what does phenomenal sound like?

Well, like I said earlier, the fun thing about building tube amps is that they each have their own sonic character. The JTM45/50 often gets compared to the Fender 5F6 Bassman because, let’s face it, Jim Marshall basically ripped the design straight from a 5F6, tweaked a few values in the circuit and slapped his name on the front.

But that doesn’t really do justice to the unique signature of the Forty-Five because it’s really a different beast. The speakers make a huge difference (2×12 vs 4×10) and the EL34s make a difference providing snappier low frequencies and more assertive mids than it’s 6L6 loaded cousin.

The real joy of this amp is that it’s not really a medium sized amp, but it’s not a big amp either. 45 tube watts is nothing to shake a stick at, but neither is it the 85 blistering watts of a Fender Twin Reverb. The Forty-Five has that magic sweet spot where you can get gorgeous edge-of-overdrive harmonic complexity at levels that are still usable, and it has the most musical feedback of any amp I’ve ever played.

This is one of those amps that inspires me to play differently, to play better, to take chances and to open up the edges of my musicianship and explore new textures, rhythms and tones. I don’t know what more I could ask from an amp.

Well, yes I do, reverb. The amp is complex enough that you really don’t need reverb, but if you’re a reverb junky like me, throw a decent reverb pedal in the mix and you’ll be in heaven.

Big Champ

photo 3.JPG by jimmyrocket02
photo 3.JPG, a photo by jimmyrocket02 on Flickr.

All amps are iconic in their own way, but in many ways collectors of the early ’50’s tweed Fender Champs have elevated them to cult status.

Originally conceived by Leo Fender as a “practice amp,” the circuit is about as simple as it gets ( 12AX7 / 6V6GT / 5Y3 ) and has a bevy of close cousins in the small amp world, but the magic of the champ for many has been its imminent recordability. Despite the small size, Champs can sound huge in a recording studio, not to mention raw, visceral, touch sensitive and harmonically rich.

I’ve built several models of the champ and have found two of them to be particularly to my liking. The ubiquitous 5F1a and its predecessor the 5C1.

The one point of contention among purists is the size of the speaker. Original 5c1 champs came with a 6″ speaker and 5F1 champs came with 8″ AlNiCo speakers, but I’ve seen them built with anything from 6″x9″ speakers to 2×12″ speakers. Vintage folks argue anything other than the 8″ and it loses that “champ sound.” They may be right, but there are a whole lot of other great sounds to be had with this circuit as well!

This is a custom build with a 5F1a circuit in a pine cab extended nearly to 5E3 size to accommodate a vintage 12″ Heppner speaker.  The circuit itself has a few mods. .01 Mallory coupling caps and a blocking resistor on the screen of the 6V6 to tighten the bass and make it play nicer with humbuckers. Mojotone (power) and Classic Tone (output) transformers bring this to life

The box is finger joined pine, covered in vox style “fawn” tolex.