Wiardgroup

For some background information on using the Boogie Filter for 
other filter types, see

http://www.musicsynthesizer.com/Circuitry/Multi-Function%20VC
F.htm

which is the section from the service manual on the Oberheim 
Expander filter. Of course the Boogie Filter uses discrete 
Vactrols rather than the CEM chip for improved noise and 
distortion.

Cell one is the 6 dB output, cell two is the 12 dB output and so 
on. Notice the inverters on the 12 and 24 dB outputs, which 
makes the math "trick" work.

You can get some idea of mixing coefficients from the resistor 
values in the summing networks.

Or just goof around and try stuff!