Dual Four Pole

A dual filter built on the core of an all-discrete transistor design from the tape music studios of 1960s San Francisco and New York. The left side is a hipass filter, the right side a lowpass, each with two cutoff CV inputs carrying a reversing attenuator, and voltage-controlled resonance. These filters do not self-oscillate; they screech and growl instead. No IC amplifiers anywhere in the signal path.