Doepfer A-122 VCF3 Demonstration
Short Doepfer A-122 Demo by NetPierre
Starts with a sequenced bassline, generated by my Doepfer MAQ16/3 and Doepfer VCO A-110 (saw wave)
Slow LFO sinewave A-147 into QCV input
ADSR into VC2 input
Drums provided by an Elektron Machinedrum
More info on the A-100 and related stuff at http://PatchPierre.blogspot.com
Module A-122 (VCF 3) is a voltage-controlled low-pass filter, which filters out the higher parts of the sound spectrum, and lets lower frequencies pass through.
The cut-off frequency determines the point at which filtering takes effect. You can control this manually, or by voltage control (filter modulation, for instance by an LFO). Two CV inputs are available.
The cut-off slope is -24 dB/octave. The circuitry uses a Curtis chip, and is very similar to the classic Oberheim filter sound. Because of its different circuitry and controls, the A-122 has a considerably different sound to the A-120 ‘Moog-like’ filter, especially in the way the resonance behaves.
Voltage controlled resonance: on the VCF 3, resonance can be controlled not just manually, but by voltages as well, right up to self-oscillation. In this case, the filter behaves like a sine wave oscillator.