When Dave Smith released the Tetra in 2009, he essentially squeezed half a Prophet 08 into a box smaller than a shoebox—four voices of pure analog synthesis in a desktop unit that weighs less than a kilogram. It became the rare kind of synth that proved you don't need keys or a massive footprint to create seriously deep, evolving sounds.
The Tetra runs a 100 percent analog signal path with four independent voices, each equipped with two digitally controlled oscillators offering sawtooth, triangle, square with variable pulse width, and noise. Each oscillator gets two sub-oscillators tuned one and two octaves below, which is where the Tetra's bass character really shines. The filter section uses classic Curtis ladder chips in switchable 12dB or 24dB per octave modes with self-oscillation and feedback, paired with three HADSR envelope generators and four LFOs per voice for serious modulation depth. The modulation matrix gives you 20 sources and 47 destinations to route control signals wherever you want them to go.
The front panel keeps things manageable with four assignable parameter knobs that can control any patch element, while a free Mac and Windows editor lets you dig deeper into the architecture without menu diving. You get a 16-step, four-row sequencer per voice, an arpeggiator with multiple modes, and three operational modes: Program mode for traditional four-voice polyphony, Combo mode for stacking different sounds across voices, and Multi mode for multitimbral work across separate MIDI channels. Four individual quarter-inch outputs plus stereo headphone out give you routing flexibility, and the Polychain feature lets you link multiple Tetras or Prophet 08s together for expanded voice count.
The Tetra earned respect from the community for its warm, characterful sound and surprising versatility despite its compact size. Users consistently praised the bass response from those sub-oscillators and the ability to create thick unison patches or run four completely different sequences simultaneously. The main trade-off is the limited front panel real estate, though the editor solves that for deeper editing sessions.
