Module A-124 is a special 12 dB multimode filter using the "strange" filter circuit of the "EDP Wasp" (an analog synthesizer with black / yellow housing manufactured by the UK company "Electronic Dream Plant" at the end of the seventies). Hereby digital inverters would be 'misused' as analog operational amplifiers, leading to distortions and other "dirty" effects that generated the specific sound of this filter. The filter is equipped with a band pass output and a combined low / notch / high pass output. For this output a control knob controls the relation between the low and the high pass signal. If both signals appear at the same level (i.e. the middle position of the mix knob), one obtains a notch filter. Otherwise the low or high pass signal predominates.