Combine Minimoog and SP ?

rhdf · Joined: Jul 11, 2014 Posts: 39 Location: Sweden

I'm sketching on a module where I can switch between 2 different filters.

So with a switch I can select between minimoog or one of the modes in the SP filter. I will also have a "bypass" where the signal simply goes directly between the input and output.

Looking at the schematics for the minimoog and the SP I notice that they both have input and output buffers. Ideal would be to be able to combine those to one, instead of having one set for each filter.

The Cutoff and resonance controls will be CV-controlled. For the minimoog there is a solution presented here http://electro-music.com/forum/topic-57121.html. Im now trying to figure out a solution for the SP filter. Any suggestions?

Then there might be a problem with having 2 filters listening to the same CV settings when only one of them actually is in the audio-path.
For example if I use the minimoog and for some reason cranking the resonance up to max, then the SP will start to self-oscillate

The simple solution seems to be to switch off the output as well and letting the unused filter do "whatever it wants" without interfering

Anything else I've missed? (this might be fun)