The Doepfer Module explained :-)
Deep bass nine process sound in Doepfer Module and Dalek,Note control and Gate Doepfer MAQ 16/3,Gate control Morphing Filter A-107
The fascia of the A102 uses a standard Doepfer VCF layout with an audio input and output, controls for audio level, cutoff frequency, resonance and one fixed and two variable frequency-modulation CV inputs. The circuitry is based on an old analogue low-pass filter design utilising an arrangement of diodes as an element of the filter control stage, as opposed to transistors or chips. This 18dB-per-octave design is supposed to impart a particular character to the filter, and I’d certainly agree — I thought it was an unusual but not unpleasant sound. Fully open, the filter exhibits plenty of top end, which can sound a little buzzy when using raw square or sawtooth waveforms. The bottom end isn’t nearly as interesting until the resonance is turned up, when some unusual interactions come into play. And adding more resonance introduces an increasingly unstable quality to the sound. At maximum resonance, the filter sounds like it is being overdriven, but with a superimposed undulating whistling effect. When it is self-oscillating (and without an input signal) it produces an ordinary sine-wave output.