dx7

dx7 · sources · schema v1

Pure-TypeScript 6-operator DX7-style FM synthesizer. 32 algorithms, 5-voice polyphony via the polyPitchGate cable, bundled bank of factory-inspired patches (E.PIANO 1, BASS 1, HARMONICA, STRINGS 1, MARIMBA, etc.), and a .syx file picker for loading custom 32-voice cartridge dumps (in-memory only). On top of the six per-operator DX7 envelope generators, a per-voice master OUTPUT-VCA ADSR (Attack / Decay / Sustain / Release) gives a player-dialable amplitude swell / long-release without editing the SYX: one envelope per voice multiplies the summed-carrier output, gated by the same note-on/note-off as the operator EGs (soft/click-safe retrigger). Defaults are ~pass-through (fast attack, full sustain, fast release) so loaded patches sound identical until you touch the master ADSR; a long master release now outlives operator-EG silence (a voice frees only once both the operator EGs and the master amp envelope have faded). NOT a Plaits-backed implementation — see .myrobots/plans/dx7-and-polyphony.md for the design rationale.

A 6-operator FM synthesizer modeled on the Yamaha DX7. Each of its six operators is a sine oscillator with its own pitch ratio and 4-stage envelope; instead of filtering a rich waveform, the operators modulate each other's frequency — one of 32 fixed ALGORITHM wiring diagrams decides which operators are CARRIERS (heard at the output) and which are MODULATORS bending a carrier's pitch faster than you can hear, which is what sculpts FM's metallic, bell-like, and electric-piano timbres. Pick a classic DX7 voice from the PRESET menu (or load your own .syx cartridge), choose an algorithm, and play it polyphonically: it allocates up to 5 voices, one per incoming note. A player-dialable master ADSR sits on top of each loaded patch's built-in operator envelopes for extra swell and release shaping.

the faceplate

3 inputs · 1 outputs · 8 params

about this module

Hover a control, or open the patch panel and hover a jack.

inputs

id	cable	what it does
`poly`	polyPitchGate	The polyphonic note source and the preferred way to play this synth: a poly cable carrying up to 5 pitch+gate voice pairs (patch a poly sequencer, MIDI LANE, or keyboard here). Each lane drives one voice — a rising gate on a lane triggers a fresh note-on at that lane's pitch, the falling gate releases it, and while a lane's gate stays high its pitch is tracked live so the note glides. When all voices are busy a new note steals the oldest. poly pitch+gate bus; 10-channel poly bus (5 pitch + 5 gate lanes)
`pitch_cv`	cv	Mono V/oct pitch for legacy single-voice playing — used only when nothing is patched into POLY. It drives voice 0's pitch, paired with the mono GATE input. 0 V is middle C; transpose and the patch's own transpose offset it. control voltage (CV)
`gate`	gate	Mono note-on/off gate for the single-voice (PITCH CV) path — level-sensitive: the rising edge triggers a note-on on voice 0, the note sustains while the level stays high (and follows PITCH CV for glides), and the falling edge releases it. Patch an envelope/clock gate or a keyboard gate here; the POLY input is preferred for polyphony. gate / trigger; gate — acts while the level is high (reacts to both edges)

outputs

id	cable	what it does
`out`	audio	Mono audio: the summed carrier output of every active voice, after the per-voice master ADSR and the LEVEL control. It's attenuated internally so all 5 voices sounding at once stay clear of clipping. Patch it into a VCA, filter, mixer, or straight to the output. audio signal

params

id	label	range	default	curve
`algorithm`	Algorithm	1..32	5	discrete
`voiceCount`	Voices	1..5	5	discrete
`level`	Level	0..2	0.7	linear
`transpose`	Transpose	-24..24st	0	linear
`attack`	Atk	0.001..5s	0.001	log
`decay`	Dec	0.001..5s	0.1	log
`sustain`	Sus	0..1	1	linear
`release`	Rel	0.001..5s	0.005	log

controls

control	what it does
Algorithm	Which of the 32 DX7 algorithms wires the six operators together (1–32) — each algorithm fixes the carrier/modulator routing, so this is the biggest single shaper of the timbre's character (stacked FM chains vs. parallel additive tones). Editable live while playing; the loaded preset starts from its own stored algorithm. Shown on the ALG readout above the knobs.
Atk	Master output-VCA attack time (per voice) layered on top of the preset's built-in operator envelopes: how long each note takes to swell to full amplitude after note-on. Near the 0.001 s minimum it's effectively instant (the default, so loaded patches sound as designed); raise it for a slow fade-in.
Dec	Master-VCA decay time — how long each note takes to fall from its peak to the sustain level after the attack. Part of the player-dialable amplitude envelope on top of the patch's operator EGs.
Dx7 preset select {n}	Voice/preset selector — pick a built-in DX7-style patch (e.g. E.PIANO 1) or, once you've loaded a .syx cartridge, one of its voices. Choosing a preset loads its operators, feedback, and stored algorithm into all voices. Use the LOAD .SYX BANK button below to import real DX7 cartridge files, which then appear in this menu.
Dx7 syx input {n}	Load .syx bank — import a real Yamaha DX7 cartridge (.syx) file; its 32 voices are parsed and added to the preset menu above so you can select them. A status line reports how many voices loaded (or any parse warnings).
Level	Master output gain for the whole synth, 0 to 2 (1 = unity); scales the summed voice bus feeding OUT.
Rel	Master-VCA release time — how long a note takes to fade to silence after its gate falls. Near the 0.001 s minimum (default) the note ends quickly; raise it for long tails. The voice frees only once both this master envelope and the operator EGs have faded.
Sus	Master-VCA sustain level (0 to 1) — the amplitude a held note settles at after attack+decay, maintained until the gate releases. 1 (default) is full level, i.e. effectively pass-through of the patch's own envelopes.
Transpose	Global pitch offset in semitones (-24 to +24) applied to every voice on top of the preset's own transpose — shift the whole instrument up or down by up to two octaves.
Voices	Polyphony cap, 1 to 5 — how many notes can sound at once before a new note steals the oldest voice. Set it to 1 for a strictly monophonic patch, or up to 5 for full chords.

source

dx7.ts on GitHub.