resonance with a svf

[Martin Czech]

Of course the poles of the filter can be made to move in the right
s-plane. Problem: a real filter has parasitic poles as well (op-amps,
otas). This will mean that oscillation will start at higher frequency
settings where still nothing happens at the bottom.
There are compensation techniques for the parasitics, 
these where proposed in E.N. AFAIK.

m.c.

:::From: modlar at gmx.net
:::Date: Thu, 10 Aug 2000 21:21:16 +0200 (MEST)
:::To: synth-diy at node12b53.a2000.nl
:::Subject: resonance with a svf
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:::Hi all !
:::
:::Thanks for all the good ideas to solve my problem.
:::
:::I am just working on the filter with the 3080 (the LM does
:::not work, so I gave up). 
:::
:::My next question (Sorry, only questions...) is :
:::is it possible (theoretically) to design a state var filter,
:::(like the formant filter, for example) that is able to 
:::"self-oscillate" ? Some months ago, I remember that someone
:::said, that a SVF is not able to produce self oscillation. 
:::Is that true ? Or, if not, what is to change ?
:::My filter design looks like the formant filter, but with 
:::2 074-OPAmps instead of the BF245's.
:::How can I produce self oscillation (squeeeeeeeeeez!!!!!) ?
:::Changing of R19 (decrease to 0 Ohm), R18 (decrease to 0 Ohm) 
:::does not work, and amplification of the resonant pathway (before
:::P5, using an OPAmp) does not help either.
:::Arhhgrggrgrg !!!!!!!
:::
:::Any help ????????? 
:::
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