Analogue Overdrive and Distortion Module

The PCB for this project is no longer available

The Euro format overdrive. The module width is a tiny 6HP wide.

Euro and Frac sized version of our popular 5U Overdrive and distortion module.

This is a simple but very effective waveform modifier module. It has two basic modes selected by a switch. Hard clipping is a hard edged distortion type effect useful for grunging up your signal. Soft clipping is a more subtle effect and produces a clean sounding overdriven amp sound.

Three front panel pots control the sound. Gain controls the overall gain of the 'pre-amplifier' stage and essentially determines the level of overdrive or distortion. The Timbre control is an effective EQ control that affects the frequency response of the effected output. The Balance pot is essentially a wet/dry mix control that allows you to add only as much of the effect as you want.

Voltage control is determined not within this unit, but as part of the signal chain placed before this module. Using a VCA to control the signal level that is fed into this unit will determine the strength of the overdrive or distortion. Using a VCF to alter the timbre of the signal fed to this module will control the overall harmonic level far more than using a filter alone. In fact, hard sync type sounds can be easily obtained by simply sweeping the filter's cut-off frequency.

The 3U Overdrive PCB ready for mounting onto the front panel. PCB size is 83mm (height) x 71mm (depth). Both pots, brackets and the switch are available from Krisp1.

PCB size is 71mm (deep) by 83mm (high). Power can be either +/-15V or +/-12V via Euro style or MOTM/Frac power headers. Current draw is approximately +/-15mA at 12V.

Sound Samples

All the following samples recorded with a small modular set up comprising of one VCO, one COTA filter, one Overdrive, two ADSR/VCA and a midiDAC to control them all. The Oakley Overdrive module is connected to the -24dB/octave output of the COTA VCF module and its output is fed to the ADSR/VCA module for final volume shaping.

The Overdrive module in these examples is our 5U version. However, the circuitry is identical to the 3U module and operation is not affected by the supply voltage.

A lightly overdriven solo sound using the COTA VCF to shape the harmonics heard

More overdrive with the COTA set to highish resonance and swept with an ADSR, firstly on slow attack, then quicker.

A small sequenced loop with the Overdrive module in distortion mode. The wet-dry pot and COTA's cut-off are being manually altered

Project Downloads

Builder's Guide

Construction Guide Our handy guide to building Oakley DIY projects

Parts Guide Our handy guide to buying parts for Oakley DIY projects

Links to schematics are available to purchasers of the PCB or module and will be sent via e-mail when the board(s) are shipped.

Front panel design and sizes in mm.

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Copyright: Tony Allgood.
Last revised: November 28, 2018.