Beavis Audio Research Trotsky Drive


Beavis Audio

A while ago, I found a chap from Moscow selling NOS Russian transistors on the bay. I ordered a box of KT312 silicon NPN devices and within a few weeks, my package from the former Soviet Union arrived. I had been playing around with single transistor designs to achieve a boost/light overdrive design that added sparkle and a nice high-end. After various attempts, I came up with a design based on the old Electra distortion, a module fitted in Electra guitars in the 1970's. The Trotsky is very similar to the Electra, but adds germanium clipping diodes, a bright switch, variable gain and a volume control.

The resulting pedal is a delightful little number that is equally at home directly into a tube amp or sandwiched in large pedal chain. My favorite discovery with the Trotsky is that it brightens up even the darkest of amps, including my nasty stock Epiphone Valve Jr. And it does so without getting trebly over ice-picky (which is funny because Leon Trotsky was killed by Stalin's goons with, you guessed it, an icepick.).

After some refinement and listening tests, I built a few units for friends and stompbox fiends.

The controls, from left to right are:

  • A bright switch. This is really useful when you are switching between single-coil and humbucker guitars. With single coils, flip the bright switch off. For humbuckers, turn it on to add the high-end that the Trotsky does so well.
  • Gain Knob: Control the gain by increasing the resistance to the collector side of the transistor. Like all pedals that use this gain topology, you can hear a bit of crackle as you turn the gain knob.
  • Volume Knob: Louder or not louder.

The differences between the prototypes and production include a swap of the 6.8nf Bright cap to a 22nf cap to roll off highs at a more useful frequency. Second, the rollbar on the top has been eliminated due to part sourcing and cost issues. Finally, I've used very bright chrome knobs to round out the Soviet kitsch look.

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