Polyfusion HPVCF Trouble

R.Fahl 8brain at spiritone.com
Mon Jun 30 21:02:36 CEST 1997


I recently finished building a copy of the Polyfusion Highpass VCF that's
on Kevin Lightner's Synthfool page.   I'm having trouble getting it to work
properly - when I pump audio into it, it works sort of like a highpass
filter, kinda buzzy and I can sort of sweep through the cutoff range,
though it is limited.  I have no control over resonance, but it seems like
it is resonating on its own.  When I have no audio going into it, it puts
out a high frequency oscillation that's barely audible.

One change I made was that I substituted 2N4392s for the E-112s that the
circuit calls for.  Is this a good substitute?  If not, what would be?
Would changing the biasing resistors fix the problem?

For those of you who are interested, here's the URL for the diagram:

http://www.synthfool.com/polyvcfhi.gif

I appreciate any advice that might help me get this stillborn module
operational.

Romeo

An unexpected demographic and cognitive constellation co-occurs with
synesthesia: females and non-right-handers predominate, the trait is
familial, and memory is superior while math and spatial navigation suffer.
Synesthesia appears to be a left-hemisphere function that is not cortical
in the conventional sense. The hippocampus is critical for its experience.
Five clinical features
comprise its diagnosis. Synesthesia is "abnormal" only in being
statistically rare. It is, in fact, a normal brain process that is
prematurely displayed to consciousness in a minority of individuals.

(http://psyche.cs.monash.edu.au/psyche-index-v2.html)





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