YM engine

All engines · Modes and shared controls

Use YM for Genesis-style FM bass, brass, reeds, bells, and sharp arcade leads.

How the sound is made

Four operators use YM2612-style algorithms, envelopes, feedback, and pitch or amplitude modulation. The operator envelopes use chip rates and attenuation levels. This engine is separate from FM6.

YM HOME page showing its four main sound controls and first factory preset.
YM on HOME. These knobs apply to the selected track unless HOME LEVELS is enabled.

HOME knobs

Knob 1 Knob 2 Knob 3 Knob 4
ALG FB D2R LEVEL

For HOME LEVELS, see HOME and mixer.

Engine controls

Press the panel EDIT button to cycle the engine pages. Pause between presses to avoid opening its shortcut layer. The musical EDIT key is a different control.

FM4 page

YM FM4 page from the running firmware, including its four control labels.
FM4 is engine page 1.
Control What it changes
ALG Select one of eight operator algorithms, numbered 0–7.
FB Set chip feedback from 0–7.
D2R Set the shared second decay rate, 0–31. Higher rates decay faster; zero holds this stage.
SSG Select OFF or one of eight special envelope shapes.

OPN page

YM OPN page from the running firmware, including its four control labels.
OPN is engine page 2.
Control What it changes
LFO Select OFF or a chip LFO rate.
PMS Set pitch-modulation sensitivity, 0–7.
AMS Set amplitude-modulation sensitivity, 0–3.
LEVEL Set the engine output gain.

Operator envelopes and tone

The common track ADSR does not set YM's amplitude envelope. Use the four OP ENV pages and OP LEVEL.

Control Meaning
AR Attack rate, 0–31. Higher is faster. Zero does not produce a normal rising attack.
D1R First decay rate, 0–31. Higher is faster.
D1L First decay attenuation, 0–15. Higher is quieter.
RR Release rate, 0–15. Higher is faster.
TL Total attenuation, 0–127. Higher is quieter; zero is the loudest setting.
MUL Operator frequency multiplier, 0–15. Zero means one-half, not silence.
DT Fine detune, −3 through +3.
KS Shared key scaling, 0–3. Higher settings make envelopes speed up more on higher notes.
AMOPS Operator mask, 0–15. Enables amplitude modulation on selected operators.

OP1 TONE through OP4 TONE select each operator's MUL, DT, and TL. KS is shared even when shown on an operator page. D2R and SSG are also shared across the operators.

AMOPS uses bits 1, 2, 4, and 8 for operators 1, 2, 3, and 4. For example, 5 enables operators 1 and 3; 15 enables all four. AM needs LFO, AMS, and an enabled operator. PMS controls pitch modulation separately. An SSG shape can repeat or hold an envelope stage. Try it first on a held note.

Try these changes

Change bass bite

Load MD BASS. Compare FB values while repeating a short note. Then change D2R to adjust the held part of the envelope.

Add vibrato

Load MD REED. Select a slow LFO rate and increase PMS from zero. For tremolo, use AMS and enable the required operators with AMOPS.

Factory presets

MD BASS, FM BRASS, METAL BELL, MD SLAP, MD REED, ARCADE LEAD, MD EPIANO, MD CHIME.

See the inspired preset catalogue for the references behind the newer sounds.

Limits and useful checks

YM has at most six voices per track within the shared eight-voice budget. The instrument includes the chip ladder DAC behavior. It does not expose PCM streaming, channel-3 special mode, or CSM timer playback.

Save a user preset or project before loading another sound if you want to keep your edits.