Old school state variable 12dB/octave filter. Voltage controlled cutoff frequency and resonance. High, band, and lowpass simultaneous outputs. Resonance is uncompensated and when cranked will get loud to the point of overdrive and clipping.
There are four CV inputs that control the cutoff frequency and two that control resonance. These are adjusted such that a 5 volts signal (likewise +/-2.5 volts or -5 volts) will give a full sweep of that parameter.
With resonance added, a trigger/gate/hard-edge-waveform at the input will be enough to excite the filter into self oscillation, and awesome bongo/tom/kick sounds ensue. Very cool as a percussive generator.