CUTOFF rotary control, which varies the filter's cutoff frequency over an eight-octave range.
RESONANCE rotary control, which varies the shape of the filter's response, from pure lowpass to actual oscillation.
ENVELOPE AMOUNT rotary control, which adjusts the amount that the input signal's envelope sweeps the filter cutoff frequency.
MIX rotary control, which crossfades continuously from unfiltered to filtered audio.
DRIVE rotary control, which adjusts the gain of the audio input.
SMOOTH-FAST rocker switch, which chooses between smooth and fast envelope follower response.
2-POLE 4-POLE rocker switch, which chooses between 2-pole (bright) and 4-pole (deep) filter frequency response.
LEVEL, a three-color LED that is used to set the DRIVE control.
ENV, a LED that indicates the strength of the envelope voltage.
BYPASS, a two-color LED that tells whether the filter is on or bypassed.
ON/BYPASS, a rugged, smooth-acting stomp switch.