Boomstar SEM V2 Semi-Modular Analog Synthesizer Module

Born from a loving recreation of Tom Oberheim's legendary SEM filter, this semi-modular beast delivers that iconic 12dB/octave character—boxy, reedy, and boomy—in a compact desktop module built to evoke the golden age of analog synths.

Two discrete voltage-controlled oscillators offer saw, triangle, square, and pulse waves with sub-oscillator, OSC1-OSC2 sync, and extensive mixing options including white noise and ring mod, all feeding into the hand-matched transistor filter with five classic types and sweepable low-pass to high-pass modes. Dual ultra-snappy ADSR envelopes—one for filter, one for the voltage-controlled amplifier—feature invert, loop, drone, and master modes, while a flexible software LFO and 18+ toggle switches unlock deep modulation routing via oscillator cross-mod, envelope, or LFO sources. Hands-on control comes from over 29 metal-shafted pots with fluted knobs for precise tweaks, quick-turn shafts for ring mod, noise, feedback (now diode-based for richer distortion), and VCO levels, plus overdrive for added warmth and edge. The 206x180mm steel chassis with stunning handcrafted wooden bookends (Bocote, Marblewood, or Pau Ferro) houses CV/gate inputs, MIDI I/O, external audio in, and stereo out, making it a perfect Eurorack companion or standalone powerhouse.

Players dig its intuitive layout and pure tone after the V2 refinements—clearer panel markings, improved signal flow, and that dynamic diode feedback bring vintage vibe with modern reliability, though some note the monophonic voice keeps it focused on leads and basses rather than chords.