AFB-16

The AFB16 Analog Filter Bank was the world's first "analog plug-in", making it a totally unique innovation.
Combining the sonic superiority of Waldorf’s analog technology with the flexibility of a digital musical computer system, the Waldorf AFB16 can be seamlessly integrated into the computer-based production environment of the modern studio.

Connecting the AFB16 to the computer using a standard USB cable, the AFB16 automatically integrates itself into the digital production environment making 16 real analog filters available to any compatible host system. Full dynamic control of the filters is achieved inside the host system and plug-ins like the ROT Analog Filter Step Sequencer, the PPG Red or the Messing.

ROT (German for "red") is a pattern based step sequencer that is capable of producing tempo-synchronized filter patterns for cutoff and resonance.
The PPG Red is a classic wavetable synthesizer, at last with real analog filters.
MESSING (German for “brass”) makes extensive use of the Waldorf AFB-16’s analog VCA’s to distort stereo or mono signals reaching from warm, analog saturation to brute overdrive.