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.
This is perhaps Doepfers most popular filter. Even folks who avoid Doepfers minimalist grayscale aesthetics swear by this filter. It can be subtle or it can turn your signal into wobbly mess at high resonance settings. With two outputs (BP and LP/HP) and two CV inputs this certainly is a keeper. Mr Doepfer released a limited edition version of this filter in black/yellow colour scheme. Theres a reason why its so popular.