[sdiy] Multimode filter topology

[Antti Huovilainen]

On Mon, 17 Aug 2009, David G. Dixon wrote:

>  By permanently wiring the filter as a 4-pole LP (which resonates 
> easily), the stagewise outputs can be added and subtracted in various 
> ways to arrive at all possible LP, HP and BP filter modes, and I'm 
> assuming they will all resonate (although I haven't tested this).

Congrats, you essentially rediscovered what Oberheim did in Matrix 12 ;)

Tap each the filter input and each stage output and mix with varying 
factors in the final output while always taking resonance input directly 
from last stage output.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova