The Doepfer A-124 is a voltage controlled filter module, based on the infamous Wasp EDP filter for the Eurorack A-100 system. With a very distinctive sound, used for adding rich distortion harmonics, the A-124 is a resonant filter with controls for level, frequency cut-off point, CV attenuator, resonance and mix. The A-124 also features a band pass output, and a low/notch/high pass output.