FM6SOUNDplays six-operator FMlight / dark

FM6

FM6 is six-operator FM synthesis (frequency modulation: sine oscillators, called operators, bending each other's pitch to make harmonics), in the family of the 1983 Yamaha DX7. Each part holds a whole patch; the knobs reshape it without opening it up.

plays six-operator FM

Half

SOUND

Reach it

white key C4 in the wheel

ALGORITHM

ALG

Engine

FM6

Factory sounds

8

Playing it

The keys play notes, up to six at once on a part. PRESETS walks the factory patches, then any you have saved. ALGORITHM picks the algorithm, the wiring of the six operators; PAT keeps the one the patch was made with.

MAIN's four knobs are macros that act on the whole patch:

• MLVL raises or lowers every modulator at once. Up is brighter and harsher, down is closer to sine waves.
• MRAT shifts the modulators' frequency ratios, which changes the harmonic series. Small moves are the useful ones.
• MEG stretches or shortens the modulators' envelopes: positive values slow the attack of the brightness, negative values make it snap.
• SLOT loads a factory patch (F), a voice from the bank in flash (B), or OWN, the part's own patch.

The screen draws the algorithm. Carriers, the operators you hear, are drawn in gold; modulators are white. The number beside each operator is its frequency ratio.

Try TINE EP with MLVL turned down for a softer electric piano, then up for a bell-like bark. On BELL, small MRAT moves give a different metal each step.

MAIN

Pages

OPS

FB is feedback, an operator modulating itself for a buzzier tone. It adds to the patch's own feedback.

Knob	Label	Range	Starts at
1	ALG	PAT .. 32	PAT
2	FB	-7 .. 7	0
3	MLVL	-100% .. +100%	0%
4	MRAT	-16 .. 16	0

PATCH

VMOD raises the modulators' velocity sensitivity, and DTUN spreads the carriers apart in pitch for a chorused sound.

Knob	Label	Range	Starts at
1	MEG	-100% .. +100%	0%
2	VMOD	-7 .. 7	0
3	DTUN	0% .. 100%	0%
4	SLOT	F1 .. B32	F1

OPERATOR

These pages edit one operator at a time. The first knob, OP, picks the operator; the selected one gets a double ring in the picture. OPERATOR sets its RATIO, FINE tuning and output LEVEL. OPERATOR 2 sets MODE (a ratio of the note, or a fixed frequency), DTUNE and VEL, its velocity sensitivity. OP ENV edits its envelope: STAGE picks one of the four stages, RATE and LEVEL set it, and the envelope is drawn over the picture.

Edits here change the part's own patch, and a factory patch you edit shows OWN in SLOT from then on. SAVE stores it as a user preset.

OPERATOR 2

OP ENV

Where it comes from

The synthesis is msfa, the core of the Dexed DX7 emulator, ported to integer C (Apache-2.0). The FM6 engine around it is Felucca's (GPL-3.0), in firmware/src/eng_fm6.c and firmware/src/fm6_core.c.