Hold a note. Shape the air. Save the atmosphere.

A microtonal drone instrument in your browser.
Hand-authored voices, long-form motion, recordable scenes.
No install. No account. Free.

https://mdrone.org/

• Holds a drone in the browser — pick a tonic, a mode, layer voices, and the sound is there. Open the page, press play, leave it on for an hour.
• Shapes sound slowly — macros, a breathing LFO, a second flicker LFO, and an XY WEATHER pad for brightness and motion.
• Builds real texture — eight authored voice models (TANPURA, REED, METAL, AIR, PIANO, FM, AMP, NOISE) and a 15-effect chain with plate, shimmer, freeze, hall, cistern, granular, and harmonic-bloom HALO engines.
• Evolves on its own — preset morphing, deterministic self-evolution, one-shot mutation, authored multi-phase JOURNEYs, a sympathetic PARTNER voice, and recordable gesture replay.
• Tunes microtonally — 6 built-in tuning tables, 20 curated authored tunings (Pythagorean, Kirnberger III, 31-TET, Yaman, Bayati, the house mdrone Signature hybrid…), 6 relation presets, a Scale Editor for your own 13-degree tables, per-interval ±25 ¢ fine detune, and a GOOD DRONE one-click guided-randomize.
• Visualises — an inline live-visualizer tile and a fullscreen MEDITATE overlay with 25 authored visualizers (harmonic, landscape, ritual, void) sharing one warm parchment / ember palette.
• Mixes — a master-bus drawer with HPF, EQ, mud trim, glue, drive, look-ahead limiter, parallel cathedral-IR room send, color saturation, M/S width, headphone-safe mode, and LUFS / peak metering.
• Saves + shares — named local sessions, share-URL encoding of the full scene (plus optional gesture recording and custom tuning cents), 24-bit WAV master capture.
• Works offline + installs — full service worker; once the page loads, you can hold a drone in airplane mode. "Add to home screen" on iOS / "Install" on desktop runs it as a standalone PWA.

• Layout
• Audio Engine
• Voices
• Effects
• Microtuning
• Motion & Evolution
• Mixer
• Visualizers
• Sessions, Sharing, Recording
• Keyboard, MIDI & Link
• Accessibility
• Privacy
• Reliability & Diagnostics
• Going Deeper
• License

mdrone is one screen — the DRONE instrument — with two surfaces that slide in on demand:

• The header ◉ MEDITATE toggle reveals an inline 16:9 live visualizer above the WEATHER pad. Tap it to expand fullscreen.
• The header MIXER button (next to VOL) slides up the master-bus drawer.

Everything else — header transport, preset library, voice stack, macros, breathing LFO, climate XY pad, effect chain, undo / redo + A/B snapshots, SCALE editor, GESTURES panel — lives in the main DRONE column.

All sound is synthesised in real time with the Web Audio API and AudioWorklet. No samples are loaded for the voices.

• Voices are AudioWorklet-backed. Each layer spawns one worklet voice per interval in the selected mode, mixed through per-layer gains. Tonic changes glide; interval changes rebuild with a short crossfade. Each voice carries a sub-Hz pitch-drift LFO so the stack breathes, and is panned across the stereo field for true separation.
• Climate — the WEATHER XY pad drives brightness on X and motion on Y. A user LFO adds slow breathing on voice gain. A second LFO (FLICKER, 0.5–45 Hz) is integer-phase-locked to the breather and offers AM, dichotic L/R detune, or both.
• Effect chain — 15 effects, drag-reorderable, each runnable serial (insert) or parallel (send) per preset.
• Master bus — HPF, 3-band EQ, optional mud trim, glue compression, drive, parallel cathedral-IR room send, color saturation + air exciter, look-ahead brickwall limiter (Chrome / FF; Safari falls back to native compression), bass-mono fold, M/S width, session-level loudness leveling, and pre/post-limiter analyser taps.
• Reverbs — PLATE uses a real EMT 140 IR (Greg Hopkins, CC-BY); HALL and CISTERN are FDN worklets; the master ROOM send uses a recording of Saint-Lawrence Church, Molenbeek-Wersbeek (Public Domain CC).
• Determinism — IR seeds and evolve drift derive from a per-scene PRNG (FNV-1a hash of the preset ID or share-URL seed). Same URL ⇒ same tail.
• Recording — the final post-limiter master is captured to 24-bit stereo WAV through a dedicated worklet tap (bit-identical, no codec).
• Adaptive stability — when the audio thread is sustainedly struggling (drift between AudioContext.currentTime and wall-clock), the engine auto-mitigates in three stages, each gated by a cooldown so the graph isn't flapped on noisy signals:
  1. Visuals — engages a low-power overlay (clamps MEDITATE FPS and the loudness meter). Composed with the user's persisted setting; never overwrites it.
  2. Heavy FX — temporarily suppresses shimmer / granular / graincloud / halo. The FxBar still shows them as ON with a striped "suppressed" cue, since user intent is preserved — autosave, share URLs, and snapshots all read user-intent state, not the runtime overlay.
  3. Voice density — progressively lowers the max active voice layers. The first reduction is decisive (7 → 4); continued struggle steps further (4 → 3) down to a musical floor of 3. The original cap is restored on recovery. Mitigation is fast (~9 s cooldown). Recovery is slow (~20 s cooldown + a 30 s underrun-free window) so a brief lull doesn't bounce a performance back into danger. Stages unwind one at a time. Notifications are calm and infrequent ("Audio under load — simplifying FX.", "Audio recovered."). Saved scenes, share URLs, and persisted settings are never mutated — mitigation is runtime-only.

Eight authored models with per-voice physicality (jawari nonlinearity, soundboard coupling, bellows AM, modal bowls, cabinet shaping, noise colour).

15 effects, click to toggle, long-press for the settings modal (AMOUNT + per-effect params). Drag to reorder.

• 6 built-in tuning tables — equal (12-TET), just 5-limit, ¼-comma meantone, harmonic series, maqam rast, slendro.
• 20 curated authored tunings — historical (Pythagorean, Kirnberger III, Werckmeister III, Young 7-limit, Just 7-limit, Partch 11-limit), xenharmonic EDOs (15-TET, 17-TET, 19-TET, 22-EDO, 31-TET), world (Yaman, Pelog, Bayati), concept (Otonal 16:32, Spectral Primes, Skewed Pythagorean, Cluster 22-Sruti, Hollow open-fifth), and the house mdrone Signature just × 31-TET hybrid.
• 6 relation presets — unison, tonic-fifth, tonic-fourth, minor triad, drone triad, harmonic stack.
• ±25 ¢ fine detune per interval, retunes voices live.
• GOOD DRONE — one-click guided randomize that picks a drone-friendly tuning + relation and adds gentle ±2–5 ¢ detune.
• Scale Editor — author your own 13-degree table in cents and save it locally; shared URLs bundle the full cents array so recipients reproduce authored microtonality exactly.

Five systems arranged by timescale. MORPH and EVOLVE are continuous macros; the rest live in the GESTURES panel.

PARTNER layers a sympathetic second voice at a fixed musical relation (fifth, octave, beat-detuned). Undo / redo + A/B slots keep a 50-entry history with two compare-and-return slots.

Master-bus drawer with: HPF, 3-band EQ, MUD trim, GLUE, DRIVE, LIMITER (look-ahead worklet on Chrome/FF, native on Safari), WIDTH (M/S with bass-mono fold under 120 Hz), ROOM (cathedral-IR send), COLOR (saturation + air exciter on one knob), SAFE headphone-safe mode, FADE (30 s → 20 min), pre-limiter CLIP LED, LUFS-S + PEAK meters, and VOL. RND clicks are loudness-aware so a string of random presets reads roughly equal-loudness.

25 authored visualizers in four function-based groups (B&W first within each):

• HARMONIC — pitch / phase / beat / voice-identity scenes (phase portrait, vectorscope, beating field, resonant body, tonnetz, harmonic ember…).
• LANDSCAPE — slow accreting fields (petroglyphs, illuminated glyphs, sediment strata, prayer rug, tape decay).
• RITUAL — ornate / painterly (iron filings, cymatics, crystal lattice, scrying mirror, Rothko field).
• VOID · HYPNOTIC — minimal or stroboscopic (void monolith, moiré, feedback tunnel, shortwave static, dream machine — 10 Hz flicker, warning shown).

Drone-native ethos: slow time, matte material, accrete over minutes rather than react per-frame.

• Sessions are named local saves in localStorage (Settings modal). They include scene, tuning + detune, voices, macros, climate, both LFOs, effect chain, mixer, evolve seed, journey, partner, and the optional motion recording.
• Share URLs compress the full scene; older URLs load with sensible defaults for newer fields. Custom and authored tuning cents travel inside the URL.
• REC WAV captures the post-limiter master to 24-bit stereo WAV via a parallel worklet tap (bit-identical, no codec). The button auto-starts HOLD if the drone isn't already playing, so you never get a silent file. Saves as mdrone-<scene>-<YYYY-MM-DD-HHMM>.wav, confirms with a WAV saved — M:SS toast, warns once per take past ~15 min (browser memory grows ~44 MB per 10 min at 48 kHz — render long sessions in passes), and prompts before close/reload while recording is active.
• LOOP bounces a short seamless-loop WAV at the selected length with a linear crossfade at the seam and a RIFF smpl chunk so samplers auto-detect the loop region.
• REC MOTION is a separate, opt-in capture of your live gestures (60 s / 200 events) that travels inside the share URL — not an audio file. Three captures, three concepts: REC WAV = audio file · LOOP = sampler-ready loop WAV · REC MOTION = gesture replay encoded into a share link.

Keyboard — A W S E D F T G Y H U J for tonic, Z / X for octave, Space for HOLD, Cmd/Ctrl+Z / Shift+Z for undo / redo, < / > for previous / next preset.

MIDI — Web MIDI note-in retunes tonic + octave. The header MIDI ▾ dropdown holds INPUT toggle, an Ableton-style LEARN MODE (click any control, wiggle a CC to bind), and a MAPPING… modal with templates and JSON import / export. ~52 assignable targets across macros, weather, mixer, voices, effects, triggers, and preset stepping. Multiple CCs per target are supported. Defaults: CC1 → WEATHER Y, CC2 → WEATHER X, CC7 → VOL, CC64 → HOLD, CC71–76 → DRIFT, AIR, TIME, BLOOM, GLIDE, SUB.

Ableton Link — the breathing LFO RATE syncs to Link tempo via a small chip (FREE / 1/1 / 1/2 / 1/4 / 1/8 / 1/16). mdrone reuses mpump's Link Bridge — a tiny cross-platform companion that bridges Link (UDP multicast) ↔ browser (localhost WebSocket). Run the bridge, enable Link in Settings, and any Link-enabled app syncs automatically. Nothing leaves your machine.

• prefers-reduced-motion honoured. When your OS asks for reduced motion, the DREAM MACHINE 10 Hz strobe is replaced by a slow ~0.2 Hz breath, and looping decorative animations (header marquee, MIDI-learn pulses, weather glow) are muted. Audible content is unaffected.
• Screen-reader labels on every icon button and canvas (MEDITATE visualizer, WEATHER pad, VU meter).
• 44 × 44 touch targets on touch devices — the compact mouse UI is preserved on desktop.
• Top-level error boundary so a render exception in one panel doesn't blank the whole app.
• Low-Power Mode (Settings → SESSION → LOW-POWER MODE, off by default) — for older laptops, low-end Windows machines, and weak tablets. Clamps the MEDITATE visualizer to 15 fps, throttles the loudness meter to 5 Hz, and skips the master-bus preset-change duck.

mdrone has no accounts, no cookies, no ads, no fingerprinting, no third-party trackers. Sessions, custom tunings, and recordings stay on your device. Anonymous, cookieless page-view counting via GoatCounter; a handful of feature events are deduped once per page-load. DNT disables all counting. Hosted on GitHub Pages.

Three layered systems exist for keeping audio stable and debugging it when something slips.

• Adaptive stability — described under Audio Engine. Reactive: the engine itself responds to sustained struggle by dropping visuals → heavy FX → voice density and restoring conservatively after a stable window.
• LIVE SAFE — explicit user-initiated mode in Settings → LIVE SAFE. Trades richness for reliability before stepping on stage: clamps the voice cap to 4, suppresses the heaviest FX (halo / granular / graincloud / shimmer / freeze), engages low-power visuals. Conservative revert — if you change something while LIVE SAFE is on, your change wins. Saved scenes and share URLs are not modified.
• Copy Audio Report — when the CPU warning indicator appears, tapping it opens a detail modal with a COPY AUDIO REPORT button. Produces a structured Markdown payload (browser/device, AudioContext, load monitor, adaptive + LIVE SAFE state, voice cap, user-intended vs effective FX, mixer state, audio-debug flags, optional trace ring). The same report is available in the console as await __mdroneAudioReport(). URLs are reduced to origin + path so share-encoded scene data is never included; localStorage / session names / custom tuning arrays are not read.

If the audio thread hashes or crackles, reload with ?audio-debug=trace in the URL to enable a 512-event ring buffer. Underruns auto-dump it; __mdroneDumpTrace() triggers a manual dump. Per-stage bypass flags (?audio-debug=no-fx, no-master, no-limiter, no-glue, no-eq, etc.) help isolate which DSP stage is responsible.

If you want to dig past the overview:

• Parameter reference — docs/parameters.md is auto-generated; regenerate via npm run docs:params.
• Source layout — src/components/ (React UI), src/engine/ (audio engine, voices, FX, worklets, presets, MIDI), src/scene/ (scene model, share/snapshot codec), src/microtuning.ts (tuning tables + custom registry), scripts/ (worklet bundle, doc + version generators), tests/ (node:test suites).
• Local dev — standard Vite app: npm run dev for the dev server, npm run build for a production bundle, npm run test / npm run test:unit / npm run test:e2e for the three test suites.
• CI — every push to main and every PR runs lint + typecheck + node tests + vitest + Playwright E2E + build via .github/workflows/ci.yml. Status visible from the badge above.
• Releases — tag-gated, not push-to-main. To cut a release:

  npm run release           # bumps patch (or `release minor` / `release major` / `release X.Y.Z`),
                            # regenerates CHANGELOG.md from git history, stages both files
  git commit -m "X.Y.Z — release: <summary>"
  git tag vX.Y.Z
  git push origin main --tags
  

  The --tags push triggers .github/workflows/deploy.yml, which re-runs every CI check and only then publishes dist/ to the gh-pages branch (mdrone.org). Push to main without a tag never deploys — every commit is checked but doesn't ship until you cut a release. npm run deploy still exists as a manual escape hatch from a developer machine.
• Code — full source on GitHub.

AGPL-3.0

"mdrone" is an unregistered trademark of the author. Use of the name or logo for derivative projects or services may cause confusion and is not permitted.

Built with Claude Code. Design, architecture, UX, audio chain, and creative direction by gdamdam.