A synthesizer builds sound from scratch. Play notes with the on-screen keys, the
computer keys shown on them, or by tapping — then shape the sound and watch it change.
On a wide screen the graphs and keyboard sit on the left and Sound Design on the
right, with Studio & Trim and Multi-track across the bottom. On a phone it all
stacks into one column. The Filter has a None setting if you want the raw sound with
no filtering at all.
Your settings are remembered on this computer, so when you come back everything is the way
you left it — the sound you designed and your sequencer pattern. Top-right you'll find 💾 Save
and 📂 Load to keep a setup in a file (to share it or move it to another computer), and
↺ to reset back to the start. (Your recordings and tracks aren't part of a saved setup.)
Source — what the keys play
Pick a Source (the buttons above the keys). Oscillator (🎹) plays the tone you build.
Sample (🔊) plays a
sound you recorded or uploaded in the Studio, pitched up and down by the keys (its original pitch
is C4) — turn Loop (the 🔁 button) on to hold a short clip while a key is down. Tone (〰️) is a steady
frequency generator — a clean sine on its own, unaffected by the oscillator/filter/LFO settings.
Drag the Low↔High slider to sweep the frequency from a low rumble to a high whistle, and
the Quiet↔Loud slider to change the amplitude — watch the wave get taller and shorter on
the scope while the pitch (how fast it wiggles) stays put. A tidy way to show frequency vs.
amplitude.
Two ways to pitch a sample. With ⏱ Keep length off the clip plays like a
tape or record — a higher note runs faster and so the sound is also shorter (and a
low note is slower and longer). Turn ⏱ Keep length on and it pitch-shifts
instead: the sound stays its original length at every pitch, the way autotune or a DAW does it. It
works by chopping the sound into tiny overlapping grains and re-spacing them, so you may hear a
slight granular “shimmer” — that's the trick showing its seams. Drag the Grain
slider to change the grain size and hear the trade-off: smaller grains sound rougher and
more echoey, larger ones are smoother but smear fast attacks like drum hits.
MIDI keyboard — play with real keys
Plug a USB MIDI keyboard into the computer and it plays the synth straight away — the
MIDI chip above the keys turns purple and shows your keyboard's name (the little dot flashes
as you play). How hard you press each key sets how loud the note is, and a
sustain pedal holds notes while it's down. The on-screen and computer keys keep working too.
Needs Chrome or Edge on a computer — Safari and iPads don't support MIDI, so there the on-screen
keyboard is the way in.
Oscillator — the raw tone
Pick a waveform. A sine is a single pure pitch; saw and square
are bright and buzzy because they stack up many harmonics. Watch the spectrum change as you switch.
You can stack up to three oscillators. The Editing: Osc 1 · 2 · 3 selector at the
top of Sound Design chooses which oscillator the Oscillator and Filter controls edit
(the two panels show an Osc N tag); Osc 2 and 3 have an On/Off button.
Pitch shifts an oscillator by whole semitones (try Osc 2 an octave down, −12,
for a fat bass) and Detune nudges it a few cents for a thick, chorus-y sound when two are
slightly apart. Every enabled oscillator plays together — the scope and spectrum show the combined
wave.
Filter — remove frequencies (per oscillator)
A low-pass filter removes the high harmonics above the cutoff — the sound gets
warmer/duller. Resonance emphasises the frequencies right at the cutoff. Each oscillator has
its own filter, so you can keep Osc 1 bright and open while Osc 2 is dark and
mellow underneath — pick the oscillator in the selector, then set its filter. The Envelope
and LFO (marked shared) shape the whole voice at once.
The Filter Env is a second envelope that sweeps the filter cutoff over each note instead
of the volume — the classic synth move where a sound starts bright and gets darker (or the
reverse). Turn Amount up (right = brighter, left = darker) with a low Cutoff and hear the
filter "open" on every note; it's the same A/D/S shape you know from the volume Envelope, pointed at
timbre instead of loudness.
When a filter is on, the spectrum marks its cutoff with a dashed
orange line (e.g. LP 4.0k) — drag Cutoff and watch it slide across
the harmonics, so you can see exactly which ones the filter is cutting.
Envelope — how the sound starts and stops
Attack is how fast it fades in, Decay/Sustain the level it settles to while
held, Release how it fades out. Slow attack = a soft pad; instant attack = a pluck.
The little graph beside the knobs draws the shape as you turn them.
LFO — slow wobble
A slow wave that wiggles the pitch (vibrato) or the filter (wah/wobble).
Hold — keep a tone going
Turn on Hold (the 🔒 button above the keys) and a key you press keeps sounding
after you let go — so you can move the sliders and freeze the wave without holding a key down.
Press the same key again, or turn Hold off, to stop it. When a button is purple it is on.
Studio & Trim — bring in a sound clip
The Studio is for one sound clip to inspect, trim, and use — from outside the synth.
🎤 Record mic records from your microphone (and shows your voice on the graphs); Upload
loads any sound file. Play hears the clip back through the synth's graph, and Save WAV
downloads it. ➕ Track drops the clip into a Multi-track lane. (To record what you play on
the keyboard, use ⏺ Record in Multi-track — that's where performances and layering live.)
Once you have a clip, the Trim clip strip shows its whole waveform. Drag the edges of
the highlighted region to pick the good part, press ▶ Selection to hear just that, then
✂ Trim to selection to keep it. Auto-trim silence chops the quiet ends off in one
click. A trimmed clip is what Play, Save WAV, and the Sample source all use — handy for
grabbing just one clean sound to play across the keyboard.
Multi-track — layer sounds
Press ➕ Track to drop the current clip into a lane (up to four), or ⏺ Record to
capture what you're playing — the keyboard or the sequencer — straight into a new lane
(this leaves your recorded clip alone, so a sequenced sample isn't overwritten). Hit ▶ Play to
hear them all at once, or 🔁 Loop to repeat the whole stack — great for building a beat
with a bass line and a voice on top. All lanes share one timeline (as long as the longest clip), with
faint beat and measure lines, and a bar sweeps across them as it plays. Each lane has a Mute
button (🔊/🔇) and Volume and Pan knobs.
💾 Save mix renders the layers into one WAV, and → Mix to clip loads the mix back
up top so you can trim it or play it across the keyboard.
Playing in time. Turn on 🥁 Click for a steady metronome to play along to (you hear
it, but it never gets recorded into your track), and set the speed with Tempo — it's shared
with the sequencer, so the whole piece runs at one tempo. Leave ⏺ Count-in on and the recorder
gives you one bar of clicks (4·3·2·1) before it starts, so your first note lands right on the
beat. If a take comes in a little early or late, drag it left or right on its lane to slide it
in time; with 🧲 Snap on it jumps to the beat grid so lanes line up.
Step Sequencer — make a beat
Click cells in the grid to turn them on, then press ▶ Play — a moving line sweeps the
16 steps and plays every lit cell. The top rows (C4–C5) are notes that play the exact
sound you designed with the oscillator, filter and envelope, so change the sound and the sequence
changes with it. If the Source above is set to 🔊 Sample, the melody rows play your
recorded or uploaded clip pitched to each note instead. They're a pentatonic scale, which
means any pattern you click sounds good.
The bottom rows are drums: Kick, Hat and Clap. Each row has its own
volume slider on the left — turn the drums up, a melody down, or pull one all the way to zero
to mute it. Turn on 🔗 Link melody to move all the melody volumes together (handy for making
the whole tune louder or softer at once). Use Tempo to speed it up or slow it down, Swing for a bouncy, shuffly
groove (it nudges the off-beats a little later), 🔊 Metronome to add a click on every beat
(a higher click on beat 1) so you can hear the pulse, ↻ Example for a starter beat, and
Clear to start fresh. The Octave ▲ ▼ buttons move the whole melody up or down an octave
(the pattern stays put — just the pitch shifts), so you can go from a deep bass line to a high twinkle.
⏺ To Track records the loop straight into a new track in the Multi-track panel, in time
with the beat. It starts the loop from the top and keeps recording round and round for as many
measures as you like — play the keyboard along with it if you want. Press ⏹ Stop and it
finishes the current measure before stopping, so the take is always a whole number of bars and
lines up perfectly with your other tracks. Record a drum beat, tweak the pattern or the sound,
record a bass line on top — they'll all stay locked together when you press ▶ Play in the
Multi-track panel.
Zoom & Range — see more detail
The Zoom slider sets how many cycles of the lowest note the oscilloscope shows. Turn
Hold on, play one note, then add a second (try an octave or a fifth up): zoom out to watch
the two notes build a repeating combined pattern, or zoom in to see the detailed shape.
The Range slider zooms the spectrum: drag it left to shrink the highest frequency
shown, spreading the low harmonics out so you can see them clearly; drag right to see the whole
range up to 16 kHz.
Freeze & label — study the wave
Press ❄ Freeze and the scope clears and waits (“listening…”). Now play a
sound: it fills the whole buffer and then freezes on a full waveform you can zoom into and
study. Press ❄ again to go back to live. When frozen, the spectrum labels the
fundamental (f₀, with its frequency and note) and marks its harmonics (2×, 3×, …), so
you can see exactly which frequencies make up the sound. The scope locks its timebase to the pitch it
detects, so the waveform stands still whether you play a note, a sample, or your own voice on the mic.
Compare before & after. Turn on 👻 Ghost, then freeze a sound, change one setting,
and freeze again — the new capture shows in blue (“now”) with
the previous one behind it in violet (“before”), on
both the oscilloscope and the spectrum, so you can see exactly what your change did to the
shape and the harmonics. Play the two at the same pitch and they line up cycle-for-cycle.
Turn 👻 off to hide the ghosts again.
In the spectrum, height is loudness in decibels (the labelled lines up the side) and
left→right is frequency (low to high). A pure sine makes one peak; a saw or
square makes a whole row of them — those extra peaks are the harmonics. It's the same idea as
the Fourier Camera, for sound.
📖 Go deeper — the Sound Manual
For the full science behind all of this — waveforms, harmonics, envelopes, filters, stereo and a
little music theory — with diagrams and live “hear it” examples, read the
Sound Manual.