ThreeTom Modular Steve's MS-22 — Matte Black Panel

ThreeTom Modular — Steve's MS-22 | 4HP Dual VCF

A dual voltage-controlled filter inspired by the Korg MS-20's OTA design, with one of the highest function-to-HP ratios in Eurorack.

Unlike most MS-20 clones, the MS-22 packs two dedicated filter circuits — a 12dB/oct low-pass feeding into a 6dB/oct high-pass, in series. That configuration gives you a duophonic "fighting resonance" behaviour you won't get from a single-filter clone. Both cutoff frequencies are individually CV-able, and resonance pushes considerably further than the original MS-20 — well into self-oscillation, with genuinely surprising results when the two filters compete.

What sets it apart:

• Modulation matrix — a row of switches routes the Aux CV input to spread, resonance and gain, individually or all at once, without patching a single cable. Designed to encourage happy accidents.
• Link switch — ties both cutoffs together at two different ratios, giving two flavours of band-pass with tweakable, CV-able bandwidth. Flip it mid-performance for an instant drop.
• CV over input gain — modulate filter overdrive, or use it as a built-in VCA feeding the filter.
• Bipolar monitoring LEDs on every CV destination — green positive, red negative.

Controls: cutoff, spread (distance between the two peaks), resonance, gain (from full attenuation to gritty distortion), plus an attenuator for the FCV input and a second attenuator for the ACV input.

Sweeps go from buttery smooth to screaming, and the gain stage delivers real grit when pushed. Covers a lot of the same territory as Mannequins' Three Sisters, plus those unmistakable Korg tones — all in 4HP.

Specs:

• 4 HP wide, 45mm deep (skiff friendly)
• 4-layer PCB sandwich, 350+ components
• Power: 100mA @ +12V / 100mA @ -12V
• Reverse power protection, buffered high-impedance inputs, 1K output resistor
• Recessed power header keeps the module shallow
• Machined aluminum knobs, 2mm matte black panel

Build:

Assembled and tested by a working electronics technician — precision soldering and component-level PCB repair is my day job. All joints inspected under magnification, fully calibrated and tested across both filter sections before listing.