[sdiy] Resonance control taper ?

Richie Burnett rburnett at richieburnett.co.uk
Sun Sep 11 13:14:17 CEST 2022

The state variable filter can self-oscillate if the damping is less than zero and goes negative. (Or it can even oscillate with zero damping if there are sources of additional phase lag around the loop!)

I arrange for the damping to start going slightly negative at a setting of about 8 on the "resonance" control. Below this the resonant boost in dB at the cutoff frequency is roughly proportional to the pot position. The further you go above the self oscillation point the louder the filter screams and the harder you have to drive it to "squash" or tame the resonance with the drive signal.


---- cheater cheater via Synth-diy wrote ----

>Maybe he meant he had built an SVF that was oscillation proof.
>On Sun, Sep 11, 2022 at 12:21 PM Ingo Debus via Synth-diy
><synth-diy at synth-diy.org> wrote:
>> Am 11.09.2022 um 04:55 schrieb Danjel van Tijn / intellijel <danjel at intellijel.com>:
>> oscillation-proof filters such as state variable designs
>> Huh? Is he saying that state variable filters cannot oscillate?
>> Ingo
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