keyboard triggered filter

Sean Costello costello at
Tue Nov 9 04:36:19 CET 1999

WeAreAs1 at wrote:

> Are you guys making your feedback with open microphones, or are you using
> amplified guitar strings?  This sounds like fun!

In my case, I was using straight electronic feedback - no acoustic or
electromagnetic transducers involved. The patch I was working with this weekend
was amazingly simple: I used a Moog Rogue as the main sound source. The output
of the Rogue was patched into the input of a Boss RV-3 reverb/delay pedal. One
of the stereo outputs of the RV-3 went into an amplifier for monitoring, while
the other output went into the audio input of the Rogue. By adjusting the output
level of the Rogue, the filter cutoff and emphasis, the level of the
oscillators, the delay time and dryness mix of the reverb, etc., I managed to
get some INSANE sounds. One of the beautiful aspects of the sound was the
heterodyning that would occur when a loud feedback signal combined with the
internal oscillator signals. That Moog filter overdrives so nicely! Using reverb
(as opposed to delay) resulted in sounds that were very reminiscent of guitar
feedback, that would evolve into enormous shuddering bass textures, shortwave
space transmissions, and other beautiful sounds. 

Obviously, all of these things would be attainable with a good homemade DIY
modular system, and them some. The advantage to a modular system would be the
ability to use feedback not only as an audio source, but as a modulation source
(i.e. the output of the system is used as a control voltage for FM-type
applications). If you are using a modular system, I would highly recommend using
a Moog-type filter, or some other filter that can be overdriven  - I really want
to try an MS-20 filter in this application.

Sean Costello

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