[sdiy] Filter slopes

[rsdio at audiobanshee.com]

In some respects, a self-oscillating VCF is coupled to its VCO, at least in pre-patched, non-modular synths. There are definitely some filter topologies where the resonant frequency will drift towards the input VCO frequency.

I’ve often wished that the VCO in such synths could be patched around the VCF so that the pitches of each could be entirely independent, without any coupling. This would allow self-oscillating filters to serve as additional oscillators. Of course, that’s possible with a modular. In addition, once things are decoupled, there might be some interesting sounds possible by feeding controlled amounts of the VCO into the VCF, even though the VCO is separately audible in a path that skirts the VCF.

Your idea, Ian, could certainly be tried out on a modular, but I don’t have the modules.

Brian


On Jun 11, 2018, at 4:28 PM, Ian Fritz <ijfritz at comcast.net> wrote:
> Well, suppose you have a set of filters in parallel. One way of coupling them would be to add a small amount of Output A to Input B, etc.  Don’t recall this being done in an analog synth context.  I think this would work best if there were nonlinearities in the filter response, though.  Linear coupling might be a weak effect.  Just some thoughts, haven’t tried anything like this.
> 
> Ian