Harmonic Low Pass Filter

Swell is a 14-HP valve harmonic filter at the crossroads of East and West: a precision analogue filter shaped by a Cold War-era military valve that sculpts timbre into new territories.

• A Soviet military-spec subminiature valve, actively in the signal path
• Precision 24dB/oct 4-pole analogue filter — musical, temperature-stable, and detailed
• Full control over where and how the valve shapes your sound: mode, bias, gain, and placement
• Split personality: from compressed warmth to untamed chaos — provoked by FM feedback or sheer resonance.
• Self-oscillating VCO with 1V/Oct tracking — use the valve to sculpt the waveform itself

https://www.bartolainstruments.com/product/swell/