Sismo Synths is a small electronic instrument workshop based in Porto, Portugal, with South American roots, that has been building handcrafted analog synthesizers in small series since the early 2010s. The brand grew out of an instrument-making art project, and its devices favor an experimental, DIY-leaning aesthetic — colorful enclosures, exposed knobs and patch points, and a focus on tactile, performance-oriented sound design rather than traditional keyboard interfaces.

Its catalog centers on compact analog noise-makers, drum and bass voices, and semi-modular desktop units. Notable products include the Iter, an analog synth voice driven by two 8-step round sequencers (one for triggers feeding a deep bass, one for CV controlling oscillators and decay); the Qadrox, a square-wave generator built around three analog oscillators and an 8-step sequencer with CV and sync I/O; the Tapbum, a three-voice unit pairing a bass drum, woodblock, and synth/noise/cymbal section; the Magyrus, a semi-modular desktop with three audio outputs, external clock in, and clock dividers; and the Samba desktop synth. Smaller pocket-style instruments like Mr. Knob ONE round out the line.

Sismo sells direct through its own webshop and via Etsy, Tindie, and Reverb, shipping from Portugal. The brand sits in the same niche as other boutique builders catering to experimental electronic musicians, modular enthusiasts, and players looking for affordable, character-driven analog voices outside the mainstream synth industry.

Sismo has 2 products cataloged on Equipboard, including Modular Synthesizers.