4TRAX is four synthesizer tracks, one step sequencer, shared effects, and a mixer — all in one page, fully offline. Click Start once to wake the audio engine (browsers require a click before sound).
| Control | What it does |
|---|---|
| System | Opens the System page: MIDI, audio device, recording, file handling, this manual. |
| Save · Load | Write the current work to a file, or open one. 4TRAX sniffs the format, so any 4TRAX file goes in through Load. |
| Creator | Your 3-letter creator tag and vibe — who the community library sees you as. Shows the tag once you have one. |
| Library | Opens the Library: your sound pool on the left, everything the community has shared on the right. Press again to go back. |
| Share | Publishes your sound pool, or the current project as a song, to the community library. |
| Map | Shows the MIDI CC number assigned to each control, on the controls themselves. |
| 🎹 | Shows / hides the on-screen keyboard. |
| ▶ / ■ | Transport — starts and stops the sequencer. All four tracks start together on the downbeat. |
| REC | Records the master output to a WAV file. Options live on the System page. |
| LCD | The single readout: every control you touch announces its name and value here, plus time, pattern length, BPM, and the clock source (INT / EXT). |
| Tempo · Length | Global BPM and pattern length. Tempo changes keep all tracks aligned, even mid-bar. |
| Master | Master output level. |
| Reset | Returns everything — sounds, patterns, transpose lane, tempo — to factory defaults. |
| Panic | Cuts all sounding notes immediately. |
The keyboard always plays the selected track — the lit tab above the synth panel. Use the mouse on the on-screen keys, or the computer keys A W S E D F T G Y H U J K laid out like a piano octave. Z and X shift the octave down / up.
While the sequencer is running, the keyboard changes role: keys transpose the playing patterns live instead of triggering notes — and so do notes arriving over MIDI on the selected track. To play a track instead while everything else keeps running, use either of its own switches: turn its Run off (silence that track's sequence and play it yourself) or its Transpose off (keep the sequence, play over the top). Stopping the transport plays everything directly again.
4TRAX has four tracks. Each holds one complete sound (every synth setting on the panel) and one pattern per track in the sequencer. The four sounds together are a Kit.
Voices (1–8) sets polyphony. Mode picks how they're used: Mono (one voice, last-note priority, glide), Poly (chords spread across the voices), or Unison (all voices stacked on one note — widen with Detune and Spread). Glide slides between pitches; Legato makes overlapping notes glide without retriggering. Drift adds subtle vintage-style pitch instability. The toggle in the title row switches the whole track on or off.
The dropdown in the Track module is the sound pool — a shared preset list all four tracks load from. + saves the current sound: type a name and press Enter for a new slot, or overwrite the loaded one so everything referencing it follows. Init resets the track to the default sound. The dice rolls a random sound — press + if you want to keep it.
Saving asks for a type tag too — Bass, Lead, Pad, Kick and so on. At least one is required, because the tags are what make the Library browsable once there are hundreds of sounds in it. A heart marks a favourite. Single sounds can also travel on their own as .itsapatch files via File ▸ Save Patch.
The synth page is one track's full voice. Turn any knob and the LCD shows its exact value; hover to peek without changing anything. Double-click a knob to reset it.
| Module | Summary |
|---|---|
| Oscillators | Three oscillators plus a noise source. Per oscillator: waveform, octave, fine tune, pulse width + PWM, level, filter routing, cross-modulation (OSC FM) and Free (free-running phase — important for kick drums and FM). Noise has its own type, pitch and keytracking. |
| Filters | Filter 1 with cutoff, resonance, keytracking and a dedicated modulation slot; Filter 2 (switchable) with selectable slope. Oscillators can be routed to either or both. |
| Envelopes | Three ADSR envelopes with draggable curves. Env 2 shapes the amp by default (selectable in Amp); Env 1 typically drives the filter; Env 3 is free for modulation. Toggles: Exp (exponential curves), Multi (retrigger on every note even when legato), Loop. |
| LFO 1 · 2 | Shape, rate (or tempo-synced ratio), phase, one-shot mode. LFO 1 also feeds the Track module's Vibrato knob directly. |
| Mod Matrix | Ten slots, each a source → destination → amount. Sources include the LFOs and envelopes; destinations cover pitch, filters, pan, levels and more. Select a slot in the grid to edit it. |
| Amp | Which envelope drives the VCA, drive amount, and velocity sensitivity. |
| Mix | This track's sends into the three shared effects, pan, and track level — the same controls as the mixer strip. |
Each track has its own lane of up to 64 steps, viewed one bar (16 steps) at a time — the bar buttons pick which bar you're looking at. Click a cell to place a note; drag its slider to set pitch. The playhead lights the current step while running.
Each track has its own Rate (¼, ⅛, 1/16, 1/32) and its own length. They're independent per track: a 4-step bass at ¼ against a 16-step hat at 1/16 loops together; a 12-step lane against a 16-step lane drifts through phases and realigns at the global pattern boundary. That's the polymeter engine — use it deliberately.
Scale filters played and sequenced pitches into a key. Swing and the Euclidean generator work per track.
Swing runs 50–80%, the same scale as a hardware groovebox. The number says where every second step falls between its neighbours: 50% is dead centre — straight — 54–58% is where most house and techno grooves live, and 66.7% lands the off-beat exactly two-thirds of the way along, which is a 2:1 triplet — the classic shuffle. It steps in whole percent, so a groove you like is a number you can write down and dial back.
The transport starts the whole machine, but each track has its own Run switch beside Length. Turn it off and that track goes quiet while the others keep playing — so you can leave a bassline and a hat running and play a solo live over the top on track 3. A stopped track keeps counting silently in the background, so switching it back on drops it in in phase with the others rather than restarting it at step 1. The pips on the track tabs show which tracks are armed.
Select a step (click its number) and the step panel opens. Besides the note, every step carries:
| Setting | Effect |
|---|---|
| Velocity | How hard the step plays (0–127). Scaled by the sound's velocity sensitivity. |
| Length | How many steps the note holds — notes can tie across steps. |
| Ratchet | Retriggers the note several times inside its step. |
| Glide | Slides into this step's pitch from the previous note. |
| Trig probability | Chance the step fires each pass — 100% is always, lower makes it a dice roll. |
| Trig condition A:B | Fires the step on pass A of every B loops of this track's own lane. See Fig. 3. |
| Copy / Paste / Clear | Move a whole step (locks and all) elsewhere, or wipe its locks and settings while keeping the note. |
Steps can hold chords: with a Poly track selected, play a chord onto a selected step (or record one) and all its notes are stored on that one step.
A parameter lock gives one step its own value for almost any sound control — a different cutoff on step 3, a shorter decay on step 7 — without changing the sound itself. This is the deep end of the sequencer, so here is the full recipe:
To record locks onto a step:
1 · Select the step in the grid.
2 · Press Param Rec in the step panel — the arm state is shown in pink.
3 · Turn any knobs on the synth panel. Each edit is written to that step only; the control gains a pink marker and you hear the change immediately.
4 · Leave the step or disarm — the sound's own settings come back, and the locked values now play only when that step fires.
A locked control shows its pink marker whenever the step is selected. Clear in the step panel removes a step's locks (the note stays). Locks stack on top of sound locks (next section): the sound loads first, then the step's locks override it.
A step can also load a completely different sound from the pool, just for that step — a sound lock. Pick it from the dropdown in the step panel: the step plays that pool sound, then hands the voice back. One hat track can spit out kicks, stabs and noise hits per step. Parameter locks stack on top, so a sound-locked step can still have its own tweaks.
Sound locks follow the pool by slot — overwrite a pool slot and every step locked to it plays the new sound.
Arm record with the transport stopped and the grid becomes a step-entry tape: play a note (or chord) and it lands on the current step, which then advances. Two navigation rules worth knowing:
Below the grid sits the transpose lane — a 16-step lane with its own rate and length that shifts the pitch of all participating tracks in semitones. Draw values into its cells to build chord-progression movement over bars; empty cells hold the previous value. Toggle it with On; each track opts in or out with its own Transpose switch (a drum track typically opts out). Its steps take the same A:B trig conditions as note steps.
Each track has a trance gate: a 32-cell volume-chop lane running at 1/32, drawn directly under the note grid — two gate cells per note step. It's part of the sound, so a gated pad saved to the pool chops the moment it's loaded anywhere.
With the transport running, the lane locks to the grid and resyncs at the pattern boundary. With the transport stopped, it free-runs at the current tempo — and the first key you press restarts it from the top, so the chop always opens with your note. Held keys have precedence: change one note of a held chord and the running gate does not reset; release everything and the next note starts it fresh.
The fold-out mixer has a strip per track: a fader in dB with a post-fader meter, pan, and the three effect sends. Beside them sit the three aux strips (which effect each slot hosts, its return level and mute) and the master strip with EQ (low / mid + frequency / high), stereo width, the single Compress knob (the bus compressor's parallel dry/wet — 0% leaves the master untouched, a little adds glue, full wet is classic insert squash), and the master fader.
The FX button opens the effect editors. The three send effects are global — each track chooses how much to send from its Mix module or mixer strip:
| Effect | Controls |
|---|---|
| Chorus | Off / I / II modes, level. Classic ensemble thickening. |
| Delay | Time (free or tempo-synced), feedback, modulation speed & depth, level. |
| Reverb | Five flavours as tabs — Room, Hall, Plate, Spring, Cloud. A shared Sound spine (pre-delay, decay with a live RT60 readout, tone, mod, level) plus that flavour's own character controls. Every parameter is on the panel; nothing is hidden behind a fold-out. |
| Bus Comp | The console-style master bus compressor (feedback detector, mono-summed key): In, gain-reduction meter, threshold, ratio (1.5/2/3/4/5/10), attack, release + Auto (program-dependent dual time constant), sidechain HPF (Off/30/60/105/125/185 Hz), Key source (Self, or any track for keyed pumping), makeup and Mix. Autopump stamps a ready-made pump — fast attack, a release matched to the tempo, and enough reduction to hear it — keyed from whatever the Key selector points at; turn it off to get your own settings back, and moving any comp control by hand simply drops the lamp and keeps your sound. Full controls here; the mixer's master strip carries the one Compress knob (= Mix). |
The Library button opens a page with your own sound pool on the left and everything the community has shared on the right, in two tabs — Patches and Songs. Press the button again to go back to where you were.
Browsing costs nothing. Preview auditions a shared sound on the selected track and puts your own sound straight back afterwards. Songs go further: clicking one plays it without touching your project — your sequences, sounds and tempo are put back exactly as they were when you leave. Load is the only thing that replaces your work, and it asks first.
Sharing needs a name to put on things, so 4TRAX asks for two small ones: a 3-letter tag and a vibe — Geek, Goth, Zen, Punk and so on — describing how you make things. Set them from the creator icon in the top bar. That is the whole of it: no account, no email, no password. They live in this browser.
Tags are deliberately not unique. There can be fifty creators called NLX and any number of patches called Bass1, exactly as there would be on a wall of cassettes. 4TRAX tells them apart behind the scenes, so nobody's upload is ever swallowed by someone else's identical name. Hover any shared item to see who made it, their vibe and when it went up.
Because the tag lives in the browser, sharing from a different browser or machine makes you a new creator. Set the same tag and vibe there and it will look right — it just won't be linked to your earlier uploads.
The Share icon publishes either your sound pool (every tagged sound in it — untagged ones are skipped) or the current project as a song, which needs a name and at least one genre tag. Re-sharing a pool you have added to publishes only the new sounds, so you can share as often as you like without flooding the list.
Sharing is one-way. Shared songs and sounds are forever in the community library and cannot be deleted or edited. There are no accounts, so there is nobody for a "remove mine" request to prove itself to. Share things you are happy to leave behind.
Everything you share is public the moment it is accepted. Names are screened, and there are limits on how much can be sent at once — but the real safeguard is the sentence above. If the server is unreachable, 4TRAX simply says so and nothing is lost; the Library keeps working from what it already has.
Everything saves as small JSON files from the System page. Files are the only thing that never leaves your machine — sharing to the Library is always a deliberate, separate act:
| File | Contains |
|---|---|
| Project (.itsaall) | The complete session: kit, pool, patterns, tempo, effects, MIDI map, channels. The one to use for a whole song. |
| Kit (.itsakit) | The four track sounds, the pool, and the global effect settings. |
| Patch (.itsapatch) | A single sound, for passing one preset to someone. |
| Sequence (.itsaseq) | All four patterns, the transpose lane, tempo and pattern length. |
| MIDI Map (.itsamap) | Your MIDI CC assignments. |
There is only one Load, in the top bar and at the foot of the System column: 4TRAX reads which kind of file it is, so any of the five goes in through the same door.
4TRAX boots with the factory song loaded, so there is always something to play with. Nothing is saved automatically: if you've made something you like, save a Project file before closing the page. Reset returns everything to the blank init state.
Everything MIDI lives in the System page's MIDI I/O column.
Tempo changes from the tempo knob keep all running tracks phase-aligned — sweep it live without the tracks flamming apart.