The Suzu lab

Every Suzu chapter has a live panel, and the panel is not a drawing of the synth: it is the synth. Voxo’s Suzu, the same C++ the desktop plays, is compiled to WebAssembly and runs in your browser’s audio thread. The page sends it the MIDI a controller would, receives its sound, and reads the state of every voice about sixty times a second: the pressure along a bore, the shape of a string, the opening of a reed, the energy in each mode. What you see is what you hear, drawn from the same numbers. The sound starts on each page with its button: a browser plays nothing before a click.

The lab lives beside the marble app, at /marble/suzu/ (the release candidate’s under /marble/rc/ while one is newer), composed from the same release tag — it is engine code, and the documentation site contains no second implementation of any voice, as it contains none of any operator.

Page	What it shows
The cell	the orbit and its conserved quantity; the shears; the naive update that blows up
The modal voice	each partial’s energy, the bow’s target and where the servo settles; the coupling’s refusal
The strings	the chain, the hybrid and the modal pluck side by side; the stiffness past the bound
Chaos	the rotor’s section filling the plane past the threshold; the Duffing clang
The flute	the bore’s standing wave, the jet, the overblow; the pitch against the breath
The winds	the reed’s portrait, the ledger as a live meter, CC 74’s staircase; the naive junction

Each page has a lab mode with red controls: the update that blows up, the junction that leaks, the step that breaks the stability bound. They are the reason the engine is built the way it is, and the worklet mutes full scale and restarts the engine when one runs away.

How faithful is it

The web build and a native build of the same source — the same flat surface, without fused multiply-add — render one script and are compared sample by sample, state by state. For most voices they agree to the last bit: the cell, Verlet, the hybrid, Duffing, the rotor and the sax. Where they differ — the lattice, the flute, the trumpet — it is because the two platforms’ math libraries round a sine or a power differently in the last place, and the difference stays more than 80 decibels under the sound. The negative control is red. The chaotic voices are the exception that proves the rule: a last-bit difference grows, as chaos does, and only their statistics can be compared.

The page gates run in headless Chrome: every page’s own check (the drift, the bow’s convergence, the overblow at breath 116 of 127, the ledger’s inequality) through ?gate=, and the captures the evidence keeps.

The lab’s MIDI

A page plays from its own keys and sliders; the flute page also listens to Web MIDI where the browser has it, so a wind controller’s breath blows the bore in the browser as it does on the desktop. The lab is deviceless — Voxo without an output device, the worklet pulling its blocks — so there is no latency to tune and nothing to install.