Indie synthesizer plugin · v2.4
One instrument.
Every voltage.
Voltline is a hand-built synth with dual oscillators, a deep modulation matrix, built-in FX, and MPE support. Below is a real, playable browser edition of the engine — no install, no account, no checkout.
VST3 · AU · AAX · Standalone — macOS & Windows · demo runs entirely in your browser
VOLTLINE MK II · browser edition · 44.1 kHz
Oscillators A + B
Wave A
Wave B
Filter & Amp LP24 · ADSR
FX & Master DELAY · OUT
Sound starts only after you press power, play a key, or run the sequencer. Output is gain-limited for hearing safety.
Presets factory + user bank
Sequencer 16 steps · 3 lanes
Under the hood
Four systems, one signal path.
Every block below is live in the browser edition above you just played. The desktop plugin adds the modulation matrix and MPE voice handling on top of the same core.
01 · VOICES
Dual oscillators with hard-sync-flavored detune
Two oscillators per voice — sawtooth, square, triangle or sine — drift apart by up to 50 cents. Osc B sits at 55% level under a shared waveshaper, so drive thickens the pair together instead of stacking two dry signals. Twelve-voice polyphony with oldest-voice stealing keeps CPU flat during dense chords.
- 4 waveforms each
- ±50ct spread
- 12 voices
- 2× oversampled shaper
02 · FILTER
Resonant lowpass with an envelope pluck
The cutoff knob is only half the story: every note-on fires a short envelope that snaps the filter upward and decays back, scaled by your decay time. Resonance climbs to a self-oscillating 12 dB Q. On the desktop version, six sources — both envelopes, LFO, velocity, aftertouch and the sequencer gate — can modulate cutoff, drive or pan.
- 60Hz–12kHz range
- Q×12 resonance
- Env-pluck per note
- Matrix on desktop
03 · SHAPE
ADSR that behaves differently per preset
Attack runs from 1 ms percussive snaps to two-second swells; release reaches four seconds for ambient tails. The browser edition applies the same curve math as the plugin — exponential attack/decay into a linear sustain plateau — so patches you save here translate directly. Try Amber Pad versus Acid Lead above: same keys, opposite envelopes.
- 1ms–2s attack
- up to 4s release
- exp→lin curve
- saves in presets
04 · SPACE
Delay built into the voice bus, not bolted on
Each voice sends into a shared 320 ms feedback delay whose wet level rides the master limiter — tails compress with the dry signal, exactly like running the whole synth through one bus on a desk. The sequencer's PERC lane hits the same bus, which is why hats sparkle with the patch instead of sitting dry on top.
- 320ms base time
- 42% feedback
- post-limiter send
- per-voice routing
Reference
Specifications & release history.
The browser edition on this page implements the marked subset of the desktop engine, so what you hear here is honest about what ships.
| Voice architecture | 12-voice polyphonic, dual oscillator per voice, oldest-voice stealing |
|---|---|
| Oscillators | Sawtooth · square · triangle · sine, ±50 ct detune spread, shared 2× oversampled waveshaper |
| Filter | Resonant lowpass, 60 Hz – 12 kHz, Q up to self-oscillation, per-note envelope pluck |
| Amplifier envelope | ADSR — attack 1 ms – 2 s, decay 5 ms – 3 s, sustain 0 – 98 %, release 10 ms – 4 s |
| FX (browser) | 320 ms feedback delay bus (42 % fb), drive/waveshaper, master limiter |
| FX (desktop) | Adds stereo reverb, chorus, bit-crusher, EQ and a 6-source modulation matrix |
| Expression | MPE per-note pitch/pressure on desktop; velocity + aftertouch routing |
| Formats | VST3 · AU · AAX · Standalone — macOS 11+ / Windows 10+ |
| Sample rate | Any system rate; internal processing at native rate, no upsampling forced |
| Browser demo | Web Audio only — zero network calls, presets stored in localStorage, works offline once loaded |
- Changelog
- 2.4 Sequencer lanes + env-pluck filter. Three-lane step grid with lookahead timing; every note-on now snaps the filter before decaying into your cutoff setting.
- 2.3 Preset bank portability. Save, delete and export/import the whole user bank as plain JSON files you own.
- 2.2 Drive stage rebuild. Waveshaper moved post-mix so OSC A and B saturate together; 2× oversampling kills the aliasing.
- 2.1 Voice-stealing policy. Oldest-voice steal replaces last-played, holding sustained chords stable under dense input.
- 2.0 Dual-oscillator core. Full rewrite of the voice card; MPE handling and the modulation matrix arrived with this release.
Licensing
Three tiers, one engine.
Every tier below describes a fictional commercial product — this page has no checkout. Each button opens an honest panel explaining exactly what that tier would include, and the instrument above stays free forever.
| Capability | Browser demoFree · local | Intro$49 one-time | Standard$99 one-time | Studio$149 one-time |
|---|---|---|---|---|
| Polyphonic dual-osc engine | Yes | Yes | Yes | Yes |
| Filter + ADSR + delay | Yes | Yes | Yes | Yes |
| Step sequencer | 16 × 3 | 32 × 4 | 64 × 8 | 64 × 8 |
| Factory presets | 6 | 64 | 240 | 240 |
| User preset slots | localStorage | 128 | 512 | Unlimited |
| FX modules | Delay · drive | 3 slots | All 6 | All 6 |
| Modulation matrix | — | — | Yes | Yes |
| MPE per-note expression | — | — | Yes | Yes |
| VST3 / AU / AAX plugin formats | — | Yes | Yes | Yes |
| Commercial-use license | — | — | Yes | Yes |
| Priority support | — | — | — | Yes |
| Choose tier |
No payment happens on this page. Tier buttons open an information panel only. Perpetual licenses — no subscription, updates within a major version are free. Try before any decision — the browser instrument is the real engine, not a video.
Manual
Five things to try in thirty seconds.
- Press power or any key. Audio never starts until you do — browsers require the gesture, and so does our hearing-safety design.
- Play a chord with Z X C V. Those are C D E F; S D G H J land on the black keys. The octave buttons shift the whole bed.
- Pick Amber Pad, then Acid Lead. Same keys, opposite envelopes — that difference is the ADSR section doing its job.
- Drag CUTOFF down while holding a note, then push RESONANCE past 0.9. The filter starts to sing on its own.
- Hit PLAY on the sequencer, then click steps in the LEAD lane to rewrite the melody live at 112 BPM.