Rhythm & Detonation

Echo Preamp

I made this pedal for Travis Paduano, whom I'd already made a Radar Rat pedal. Travis wanted a mellow overdrive/boost to add a little warm texture to his already driven amp. I decided to build him the preamp off the famed Echoplex® EP-3® tape echo unit. There are a lot players who started using the Echoplex as a preamp because they liked the mild boost and thick coloration it gave their sound.

This circuit uses madbean's Fatpants project PCB and is a single J201 jfet booster. The trick to getting the Echoplex sound is running the circuit at a higher voltage than can be provided by a 9v battery. To do this, the circuit uses a MAX1044 charge pump, which increases the voltage to 17v from 9v. There's an internal trimmer for adjusting the drain voltage for biasing purposes. There are two external pots: THICKNESS, which adjusts the SOURCE bias, and a master volume that selects the amount of boost.

The pedal sounds very thick and warm and is great for driving an amp into warm sweet overdrive. It's a very mild boost that adds a nice texture to the sound. It makes single-coil pickups sound fatter without covering up their natural sound.

For the graphics, I put a bat on the pedal to match it with Travis' rat pedal, and the bat is a slight nod to this pedal's Echoplex roots. His only request was that the pedal be yellow. I used black knobs and a water clear red LED.