[sdiy] Question about ASM-1 state variable VCF

[Happy Harry]

#3  I HAVE used the CEM 3320 in the state variable configuration
in a ProOne.  After about a year, I took it out and converted back
to a near stock design.

The SVF has much less signal handling capacity, and distorts in
an unpleasent way. The HPF and Notch filters that I used were
not too useful.

H^) harry


>From: Scott Bernardi <sbernardi at home.net>
>To: Synth-DIY list <synth-diy at node12b53.a2000.nl>
>Subject: [sdiy] Question about ASM-1 state variable VCF
>Date: Tue, 15 May 2001 06:04:14 -0700
>
>I breadboarded a state variable VCF very similar to the ASM-1;
>schematics are at:
>http://members.home.net/sbernardi/elec/og2/og2_svfilter1.gif
>http://members.home.net/sbernardi/elec/og2/og2_svfilter2.gif
>
>1. I would like a nice sustained oscillation when the Q is turned up. I
>get oscillation, but it is very frequency dependent and runs into
>clipping. I notice the ASM-1 VCF has a Q limiter built around R32, D1,
>D2, R31, and R30. There are two pins labeled Qpot and Qout.  How do you
>connect the Q pot?
>
>2. I was using TL074's; I notice Gene uses the CA3140, and Electronotes
>recommends it also, for low phase shift across the integrators. Do these
>make a difference in stability compared to TL074's?
>
>3. Has anybody used the CEM3320 in a state variable connection (I've got
>a few extra of these)?
>
>Any tips you gurus have in getting stable Q and oscillation will be
>appreciated.
>
>--
>Scott Bernardi
>sbernardi at home.net

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