The Doepfer Module A-128 (Fixed Filter Bank) is a filter bank, made up of 15 parallel band pass filters :50 Hz / 75Hz / 110Hz / 150Hz / 220Hz / 350Hz / 500Hz / 750Hz / 1.1kHz / 1.6kHz / 2.2kHz / 3.6kHz / 5.2kHz / 7.5kHz / 11 kHz.
Each band pass filter has its own amplitude control knob.
The unmodified 128 has just one output which is a mix of all the filters, depending on the
position of each one's amplitude control knob.
It's a lovely sounding filter even though it has no CV control.
It's worth adding an output for each filter.
To do this you must remove the knobs aND faceplate
Ive made a breakout panel .. 4HP