The Noise and Dual Filter module

Construction difficulty: Easy

The issue 4 Noise/Filter front panel

The Oakley Noise and Dual Filter module is used to generate non pitched sounds such as wind, surf and other ethereal sounds. It can also be used as a sound source for percussive sounds like cymbals and snare drums.

Two types of noise output are provided. White noise which when unfiltered sounds like gas escaping, and pink noise which sounds more like a big waterfall. The module's pink noise circuitry comprises of a complex cascade network designed to replicate the -3dB/octave low pass response that true pink noise requires.

The module also gives a very low frequency output or infra-red signal. This can be heard as a series of random thumps when listened to, but it is actually a randomly varying output voltage changing all the time, sometimes quickly and sometimes hardly at all. Fascinating to watch when it controls an LED, but it comes into its own when controlling filter cut-off on an otherwise static sound.

This module also features two separate and quite unusual voltage controlled one pole filters; one high pass and one low pass. A one pole filter produces a gentle -6dB/octave roll off for natural sounding noise effects. These are internally normalised to the noise generator's output, but may also be used separately to process other sound sources too.

The two filters are both voltage controlled so the cut off frequency may be controlled by an external CV signal from, perhaps, an ADSR, LFO or midi-CV convertor. A front panel pot and three way switch allows you to control the depth of the modulation for either or both filters. The pot is a 'reversible attenuator, so you are able to control not only the depth of the modulation but also the polarity.

The noise source is true analogue, a reverse biased PNP transistor.

Power (+/-15V) is provided to the board either by our standard Oakley 4-way header or header. Current consumption is approximately 30mA per rail.

The PCB size is 102mm (high) and 114mm (deep).

The issue 4.1 PCB behind a natural finish Scheaffer panel. Note the use of the optional Sock8 board to make wiring the socket field much easier.

Sound Samples

White Noise

Pink Noise

Low pass filtered noise

High pass filtered noise


Click here for how to order.

Noise/Filter issue 4.1 PCB ............................. 18GBP
Sock8 issue 4 PCB ........................................... 7GBP

Noise/Filter pot bracket kit ............................... 0.50GBP

The optional Pot Bracket Kit contains the two 16mm Alpha pot brackets required to complete one module.

All other parts can be purchased from you usual electronic component supplier.

All prices include VAT at UK rates. Shipping and postage is additional to these prices. See also the FAQ page.

Project Downloads

Noise/Filter User Manual

Noise/Filter 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

Schematics are only available to purchasers of the PCBs and will only be sent via e-mail when the board(s) are shipped.

Front Panel database

A Schaeffer front panel can be made for this module. The databases can be found by downloading the following links:

5U format in traditional black

5U format in natural silver

To read these files you will need a copy of 'Frontplatten designer' from Schaeffer. The program also features on-line ordering, so its now even easier to buy your panels from Scheaffer.

The company are based in Berlin in Germany and will send out panels to anywhere in the world. Delivery to the UK normally takes around ten days. For North American users you can also order your Schaeffer panels from Front Panel Express.

Back to projects page: Projects

Back home

Copyright: Tony Allgood.
Last revised: April 25, 2022.