keyboard triggered filter

Toby Paddock tpaddock at
Tue Nov 9 07:44:12 CET 1999

This must be *filter controlled feedback* week.
Yesterday I was playing with an Odyssey and tape delay loop.
Ody out to RE-201 delay back to Ody audio in. No VCO's.
Using a pedal to control the filter set at a fairly high Q.
Adding a small amount of pink noise would kick-start the feedback if it just wouldn't get going.
Using the spring reverb instead of tape worked better than I expected.
Pretty classic flying saucer sounds.
I really like using a cheap BBD delay for this.

 - -- -  Toby Paddock


Sean Costello wrote:

<<What you are describing sounds like a state-variable filter, with the cutoff
frequency controlled by a keyboard. This will definitely work for feedback
oscillator applications - I was doing this the other day (with a Moog filter) 
to control the pitch of feedback echoes.>>

And WeAreAs1 at wrote:
Yeah, and a SVF would also have a Bandpass ouput, which might even be the 
most useful one for controlled-feedback experiments.  A very narrow bandpass 
filter might actually allow you to sweep the feedback pitch, almost like an 
oscillator (depending on favorable environmental acoustic factors, of 
course).  You could certainly control the filter's pitch range with some kind 
of CV pedal - this would allow you to sweep through and zero in on various 
strong feedback resonance ranges.  I have my doubts about trying to come up 
with any kind of reliable feedback-pitch-to-CV device, though.

Mike B.

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