∞Open Rack · polyphonic synth
Helm synth
The sound engine of Helm, an open-source subtractive synthesizer, running in your browser. Two oscillators with unison, a sub and noise, a resonant filter, three envelopes, LFOs, an arpeggiator, a step sequencer and effects. The panel is our own; every patch here is free to share (21 in all).
Loads about 200 KB the first time.
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Edited · changes are not saved
C3
Computer keys: A W S E D F T G Y H U J K play notes, Z / X change octave. Tap a key nearer the bottom to play it louder. Double-click a slider to reset it.
About this page
What's here
- Helm's synthesis engine (the mopo DSP library and Helm's voice, filter, envelope, LFO, arpeggiator, step sequencer and effects code), compiled to WebAssembly from the GPL-3.0-or-later source.
- 5 patches from Helm's own collection that their author released under GPL-3.0-or-later. They were saved by an older Helm version and are converted the same way Helm itself converts them.
- 16 new patches made for ∞Open Rack, released as CC0 (public domain).
- A new interface, drawn for ∞Open Rack. Helm's own interface and artwork are not used.
Left out on purpose
- 269 factory presets that are licensed CC BY 4.0. This page only ships patches that are GPL or CC0.
- The plugin's own interface, skins, fonts and graphics, and the JUCE framework it uses (not needed in the browser).
- Saving patches: edits last until you change patch or reload the page.
Sound runs on a separate audio thread in your browser. Nothing you play is recorded or sent anywhere.