Sunset Circuits

Sunset Circuits is six vintage synthesizers in one instrument, completely free. A row of six mode rockers picks the engine, and each mode is a different classic circuit with its own voice, its own signature controls, and its own panel color.

Six circuits, one instrument

The layout stays the same in every mode, so you always know where things are. Only the color, the mode sub-panel, and a few mode-specific controls change when you switch circuits.

• Cosmos is an early-80s six-voice poly built on digitally controlled oscillators, with rock-steady tuning, a clean filter, and a built-in bucket-brigade chorus for that lush warm pad sound.
• Oracle is a late-70s five-voice analog poly with two true oscillators, a self-oscillating filter, and poly-modulation routing for pitched attacks and inharmonic bells.
• Mono is an aggressive monophonic voice with two oscillators plus a sub, a fat driven filter, ring modulation, and hard sync, built for basses and leads with weight.
• Modular is a 70s semi-modular voice with three oscillators, a transistor-ladder filter, linear FM, a sample and hold, and a real dispersive spring reverb, at its best on drones and sequences.
• Prism is a mid-80s four-operator FM engine with eight algorithms, per-operator envelopes, and operator feedback: glassy electric pianos, chiming bells, punchy basses, and metallic brass.
• Acid is the silver bass box: one oscillator through a screaming diode-ladder filter, with accent, slide, and a sixteen-step pitch pattern sequencer.

FM done right (Prism)

Prism gives you four sine-wave operators, eight classic routing algorithms, a full envelope on every operator, and operator feedback. The mode panel draws the active algorithm live and highlights the carriers, so the wiring is never a mystery. Build tine electric pianos, inharmonic bells, growling basses, and formant leads from scratch.

Acid with a real sequencer

Acid mode expands the sequencer into three lanes: pitch, accent, and slide. Hold one note and the sixteen-step pattern transposes with it. The diode-ladder filter screams near self-oscillation, and the accent circuit makes accented steps jump. It is a complete acid bassline machine.

Modulation and effects

An eight-slot modulation matrix routes LFOs, envelopes, velocity, aftertouch, key tracking, sample and hold, and more into pitch, filter, amplitude, pan, and effects. The built-in effects chain gives you drive, chorus, a tempo-syncable delay, and a reverb that becomes a spring reverb in Modular mode.

Presets

Sunset Circuits ships with 54 factory presets across all six modes, from warm poly pads and FM electric pianos to acid basslines and evolving modular drones. Save your own patches to a personal user preset library that follows you between projects and hosts.

Open Source

Sunset Circuits is open source under the GPL. View the source, report issues, or contribute on GitHub.

Sunset Circuits emulates the character of several classic vintage synthesizers. This project is not affiliated with or endorsed by any hardware manufacturer.