The Doepfer A-124-2 Wasp Filter Slim Line is a compact multimode filter based on the chaotic, unpredictable circuitry of the classic EDP Wasp synthesizer. Packed into just 4HP, it brings gnarly textures and raw filtering power to even the smallest modular setups.

This filter's character comes from its unconventional design: it uses CMOS digital inverters instead of op-amps, creating a distinctive, dirty sound with a rough edge. The resonance is wild and unstable—never quite tipping into self-oscillation, but always on the brink. Cranking the input level brings out even more aggressive behaviour, making it ideal for tearing up waveforms.

The module provides outputs for bandpass and a shared lowpass/highpass, plus a mix output that allows for continuous blending between lowpass, notch, and highpass modes. Despite its reduced size, the A-124-2 retains all the features of the original large-format version, save for smaller knobs for the mix and input level controls.

This is a filter with real attitude—a perfect addition for anyone looking to inject some chaos and character into their Eurorack rig.