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<DIV><FONT face=Arial size=2>You could try Yves Usson's opamp variation so that
you're dealing with a 22k variable resistor instead of 2k</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><A
href="http://yusynth.net/">http://yusynth.net/</A></FONT></DIV>
<DIV><FONT face=Arial size=2><A
href="http://yusynth.net/Modular/EN/STEINERVCF/index.html">http://yusynth.net/Modular/EN/STEINERVCF/index.html</A></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Or try a VCA style approach like Charlie
Lamm:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><U><FONT color=#0000ff><A
href="http://www2.charlielamm.com/synth/">http://www2.charlielamm.com/synth/</FONT></U></A></FONT></DIV>
<DIV><FONT face=Arial size=2><A
href="http://www2.charlielamm.com/synth/steiner/cgs35wire.pdf">http://www2.charlielamm.com/synth/steiner/cgs35wire.pdf</A></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Or go the FET route. I was planning on trying
the Vactrol approach with a VTL5C10 (some day). </FONT></DIV>
<DIV><FONT face=Arial size=2>I think I heard somewhere that the Cyndustries
filter uses something similar.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Jeff</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=nathansettembrini@gmail.com
href="mailto:nathansettembrini@gmail.com">nathan settembrini</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=synth-diy@dropmix.xs4all.nl
href="mailto:synth-diy@dropmix.xs4all.nl">send</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, May 02, 2006 7:26 PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [sdiy] Synthancon
VC-Resonance</DIV>
<DIV><BR></DIV>
<DIV>Hi,</DIV>
<DIV>I am doing a project for the Theory of Music Synthesizers class at
Georgia Tech. We have put together the Synthacon VCF filter (<A
href="http://www.cgs.synth.net/modules/cgs35_syntha_vcf.html ">http://www.cgs.synth.net/modules/cgs35_syntha_vcf.html
</A>) and are trying to add voltage controlled resonance to the
circuit. We have tried using a JFET as a voltage controlled resistor to
replace the pot but think we were overdriving the amp and getting a lot of
noise. The other thing we tried was using a Vactrol to replace the pot,
but can't figure out a way to get the resistance low enough (without supplying
rediculous amounts of current) to replace the 1k pot. Does anyone have
any ideas? Can the 2k2, 1k, and 1k pot all possibly be scaled to larger
values and the circuit still function properly? Thanks </DIV>
<DIV> </DIV>
<DIV>Kyle</DIV></BLOCKQUOTE></BODY></HTML>