OctaSine – Modulation Synthesizer

A free and open source frequency modulation synthesizer plugin (VST2, CLAP). Runs on macOS, Windows and Linux.

Four operators

Four FM operators with parameters for wave form (sine, square, triangle, saw and noise), volume, panning, feedback and frequency (ratio, free and fine), with visualizations of stereo wave forms after modulation.

Flexible routing

Flexible routing allows setting the operator modulation targets (with some limitations) as well as the amount of signal that is simply added to the final output, enabling additive synthesis.

Four LFOs

Four LFOs with multiple waveforms, oneshot and loop modes and optional DAW BPM sync. They can target most operator parameters and most parameters of lower-index LFOs.

ADSR envelopes

Each operator is connected to an attack-decay-sustain-release volume envelope with logarithmic slopes. Envelope groups make synchronizing changes a breeze.

Modulation panning

A unique feature of OctaSine is that modulation can be panned, enabling FM positioning within the stereo image. Additionally, true stereo panning is implemented, not just balance.

Cross-platform

Runs on macOS, Windows 10/11 and Linux (X11) in VST2- and CLAP-compatible DAWs on 64-bit computers. Synthesis is SIMD-accelerated on x86_64 (SSE2, AVX).