Metasonix TS-22 Pentode FilterBank

Back in 2000, this filter bank broke ground as possibly the only all-tube synth filter module ever sold, harnessing the wild, unpredictable soul of vacuum tubes for sounds no solid-state gear could touch.

At its core, four independent pentode tube bandpass filters—each with its own tune and resonance knobs—run in parallel, using simple Twin-T circuits for that raw, organic edge, then mix down to a voltage-controlled amplifier with CV inputs for both filter sweeps and VCA dynamics. A single mono audio input feeds the chaos, and the compact black chassis packs high-voltage tube grit into a Eurorack-friendly footprint, though it's a power-hungry beast true to Metasonix's no-compromise ethos. Manual sweeps let you carve brutal, formant-like textures, while CV opens doors to animated patching in modular rigs.

Over two decades on, collectors and tube obsessives still chase these discontinued gems, praising their eerie, alive resonance that screams character—though some note the tubes demand careful maintenance to keep the magic flowing without hiccups.