21 Nov
2020
21 Nov
'20
11:36 p.m.
On Thu, Nov 19, 2020 at 10:05:00PM +0100, Fons Adriaensen wrote:
Hello all,
Some people have asked me to provide a bit more documentation
on the state-variable filters I used in zita-eq1 and zita-jacktools.
So I've written a short technical note on this. You can find it at
<http://kokkinizita.linuxaudio.org/papers/digsvfilt.pdf>
I wish I was good at maths! This makes it all look so simple, and it works well.
I guess with the corrected parameters, you can't get it to self-oscillate without Q
really being infinite? With the uncorrected parameters it seems to go "over
unity" with Q set to about 10, but a soft clipper would stop it blowing up.
It behaves well if you interpolate the c1 and c2 values to sweep the filter across a block
of samples, which is handy.
--
Gordonjcp