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

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.


2 thoughts on “the Forty-Five

  1. I’ve owned this amp for about a year now. It’s now my main “pedal” amp; prefer it to my: Dr Z Maz Jr, Budda Superdrive 30, Marshall JCM 800 1959, Top Hat King Royal, VVT Lindy Fralin and a few lesser amps. Great job!

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