Synth patents, and the SSM 2040

[MACHINE MEDIA]

> BTW, I found the patent that the SSM 2040 filter supposedly falls under:
> U.S Patent number 3,969,682.  The inventor was David Rossum, and the
> assignee was Oberheim Electronics, Inc.  This patent, "Circuit for Dynamic
> Control of Phase Shift," covers the technique of using cascaded OTA/buffer
> stages to create an all-pass filter, as well as modifications to the circuit
> to obtain highpass and lowpass filters.  The circuit shown is pretty basic,

3,969,682 is the patent for "Circuit for Dynamic Control of Phase 
Shift,"  I wouldn't know an SSM-2040 if it hit me in the head, but Mr. 
Rossum has another patent with Ronald Dow, 4,404,529 "Lowpass Filter with 
Electronic Control of Cutoff and Resonance" you might find interesting.

A couple of patents relevant to ARP filters are 4,011,466 "Dynamic 
Filter" and 3,805,091 " Frequency Sensitive Circuit Employing Variable 
Tranconductance Circuit."

You can order reprints of patents from Uncle Sam for $3 each.

PEACE OUT :)
MARK