Picture of Distortion of DOOM! (for the bass)
This is an intense, synth-like distortion effect designed for the bass guitar. The project is not intended to be a complete guide to constructing a stand-alone pedal; rather, it is a guide to putting together a circuit that produces some brutal sounds and that can be used in experimentation or in other projects.

The audio file contains clips of how the effect sounds. This circuit design includes a 'mix' control that changes the balance between the original, unaltered signal and the processed signal; you can hear the effect of adjusting this control later in the audio file.

All of the electronic parts (including the parts for the bipolar power supply discussed later) for the circuit itself can be acquired for ~$15.

This circuit is not hard to put together, but basic knowledge of assembling electronics is necessary. If you intend to turn this into a stand-alone pedal, then knowledge of how to do so will of course be required.
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Step 1: Parts

Picture of Parts

Resistors (1/4W or greater rating will do)
1k (x9)
100k (x3)
10k linear potentiometer (x1)
10k audio logarithmic  potentiometer (x1)

Capacitors (16V or greater rating)
47uF (x2)

Op Amps
TL074 (quad package, x2)
14-pin DIP op-amp sockets (x2)

1N914 (x6)

Wire for connections
+/-9V power supply (for this project I used the bipolar power supply circuit from -
1/4" mono jacks (x2, input and output)
Printed circuit board, bread board, or perforated board

The schematic is shown above...
bikeNomad9 months ago

Interesting effect. One comment, though: you need to provide a DC path to ground for the input bias current at the input. Even 1M would be plenty for the 400pA max bias current.

mcmahanly1 year ago