resonance with a svf

[modlar at gmx.net]

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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