Parameters
Filter
Filter Envelope
These knobs move the module's published schema, but the preview engine only renders a few modules so far — OSC Mini, FX Mini, Amp Rig, Space Mini and the OSC-1 chain — so they won't change what you hear yet.
Keyboard
Filter
Play the module directly — nothing to cue.
Filter
The knob everybody reaches for first.
A stage of OSC-1. It works the same on its own page as it does in the chain — same parameters, same paths.
About
A resonant multimode filter - low-pass, high-pass, band-pass, notch - with an envelope contour. Nothing else in a subtractive synth changes the sound this much per degree of rotation.
Take it into your DAW.
Same DSP as this page. The plugin isn't a rebuild — it's the identical kernel from the identical TypeScript source, compiled native instead of to WASM.
Free forever, no account, and playing it in the browser will never ask you for one. VST3 and standalone today; AU and CLAP are on the roadmap.
How it works.
A second-order biquad in one of four modes. Cutoff sets its corner and Resonance sets the Q, which is emphasis at that corner rather than a separate resonance circuit - a real analogue ladder behaves differently at the extremes, and this does not pretend otherwise.
The contour is its own ADSR, separate from the amplitude envelope, sweeping from Base Freq upward by Env Octaves. That separation is the difference between this and OSC Mini, where one envelope does both jobs.
It's yours to read and to fork.
Research preview
npx codex clone filter
npm run devThe codex CLI name is proposed, not shipped. That command gives you this module's DSP, schema, presets and UI as a local project — change a number, hear it immediately.