Object: tiar/filter/ZDF SVF 1
try menu: Help -> Library -> Community -> tiar -> filter -> ZDF SVF 1 for instant psychédélic.
ZDF SVF 1 is still in dev, so feedback is welcome.
It is designed to be a "heavy duty" state variable filter, it must be capable of enduring deep and fast modulations without becoming unstable.
This object is a so called "Zero Delay Feedback" filter based on a design i made some years ago.
It is based on the "step invariant" transform (as opposed to the omnipresent bilinear transform).
The main advantage of this method is that its frequency response is similar to analog filters even in the high range of the spectrum (no frequency warping).
The maths behind it are a little more complicated than the usual trapezoïd ZDF.
For details, you can have a look to the jsfx/Reaper thread, there is two or three posts discussing transition matrixes...