Vermona Action Filter 4 Stereo Analog Filter | KraftMusic.com
Waldorf MiniWorks 4-Pole | Vintage Synth Explorer
Bastl Instruments Ikarie Stereo Analog Filter Patch #1 A Complex Oscillator Dream - YouTube
Tech group test: Hardware Filters | MusicRadar
NEUTRON FLUX - postmodular
Softube - Mutronics Mutator is essentially a super sweet stereo analog filter and an envelope follower, based on technology developed for analog synthesis in the 1960s. The Mutator was an instant success