Noise and Dual Filter

Analogue noise and voltage controlled filter module

The Oakley Noise and Dual Filter module is designed 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.

The noise source is a reverse biased PNP transistor that is available unfiltered (white noise) and filtered by complex cascade network designed to replicate the -3dB/octave low pass response that true pink noise requires. In addition the module produces 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. 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 an attenuverter, so you are able to control not only the depth of the modulation but also the polarity.

http://www.oakleysound.com/noise.htm