README from GitHub, MIT

Tracelistener's SP-404MKII Sound Generator mod

The patcher builds Sound Generator + Kits v9.52 for the SP-404MKII: Sound Generator v9.9.3 (four live voices, 17 new waveforms, nine volume/filter-envelope presets, 34 scale choices and an arpeggiator) plus thirteen synthesized machine kits. It also adds bounce in place, pad envelopes, note repeat, chromatic scales, settings saved with the project, SUB PAD on the Sound Generator, hidden effect settings and a faster start-up. It is built on, and includes, DOOM OS 0.6.1 (build ED5E), Klangfeld Labs' pattern sequencer for the SP: hold REMAIN and press SUB PAD to open it (DOOM OS quickstart). Drop in the original, unmodified Roland firmware 5.52 file and press Patch; there is nothing to choose (an already-patched file or another version is refused). Firmware processing happens locally in your browser; nothing is uploaded. Kit controls, reproduction and validation.

Keep your volume low when you try the hidden effect settings. Some of them can make the sound suddenly very loud, loud enough to hurt your ears or your speakers. Turn the volume down first, especially on headphones. The Compressor and Super Filter settings that did this in v9.47 and v9.48 are removed. If you installed v9.47 or v9.48, patch again with v9.52.

New in v9.52

Hidden settings on and off: hold HOLD and press VALUE, on any screen, to switch all hidden effect settings off (the effects sound as they do on a stock SP) and on again (your edits come back). The SP shows HIDDEN FX OFF or HIDDEN FX ON. While they are off, VALUE on the effect screen does its usual job.
Edits kept: your hidden effect settings, and whether they are on or off, are saved and come back after you turn the SP off and on.
Always there: the hidden settings now come up every time you press VALUE on the effect screen, also after you have been on other screens. Before, they sometimes stayed away until you switched the effect off and on.

New in v9.51

ROLL on START/END and PITCH/SPEED: ROLL does its usual job on those screens again: on START/END, hold it to hear the end of the sample; on PITCH/SPEED it opens Groove. It no longer switches the roll latch on or off there. If the latch is on, it waits until you leave the screen.
Stop one roll: hold EXIT and press a rolling pad to stop just that pad. The other pads keep rolling.

New in v9.50

Input FX hidden settings: hold VALUE and press EXT SOURCE, on any screen, to open the hidden settings of the input FX. For the Gt Amp Sim that includes AMP TYPE (14 steps; its standard screen has 6 amps), SP TYPE (16 cabinets) and the mic position. Each VALUE press shows the next page, CTRL 1-3 change the settings, and any other button closes them. This doesn't switch EXT SOURCE on or off. Turn your volume down before you try them.

New in v9.49

Safety fix: the Super Filter's hidden settings are gone: one of them could make the sound suddenly, dangerously loud.

New in v9.48

Safety fix: the Compressor's hidden MODE setting is gone: changing it could make the sound suddenly, dangerously loud.
No more "NO EXTRA SETTINGS": on an effect without hidden settings, VALUE works as it normally does.

New in v9.47

DOOM OS included: the firmware this patcher makes already contains DOOM OS 0.6.1 (the pattern sequencer). Everything below is added on top of it. You don't install DOOM OS separately.
Bounce in place: turn a pad's sound, with its effects, into a new sample.
1. Hold RESAMPLE and tap the pad.
2. Tap where the new sample goes: the same pad to replace it (the original moves to an empty pad), or an empty pad to put the new sample there. The pad you picked lights up. A pad that already has a sample says PAD NOT EMPTY.
3. Turn VALUE to choose NO TAIL (stop when the sound ends) or TAIL (keep the echo or reverb until it fades out).
4. Press RESAMPLE to record.
To undo a replace: hold RESAMPLE, tap that pad, press VALUE, then press RESAMPLE. BOUNCE.md
Pad envelopes: shape how each pad's sound starts and fades. Press SHIFT + PITCH/SPEED, then turn VALUE to move through eight pages: finer attack, hold and release with curves (pages 1-4), a pitch sweep and a filter with its own sweep (pages 5-7), and the curve shapes (page 8). On page 1, press VALUE for finer timing. Each pad keeps its own settings. To put a pad back to normal, press DEL on these pages, then VALUE. PAD_ENV.md
Note repeat: hold ROLL and a pad, and the pad repeats in time with the tempo. Turn VALUE while holding ROLL to make the repeats faster or slower (triplets included). Tap ROLL to keep repeat switched on. Press HOLD to keep a pad repeating after you let go. Hold EXIT and press a rolling pad to stop just that one. In chromatic mode each pad remembers its own speed. NOTE_REPEAT.md
Chromatic scales: in chromatic mode, hold VALUE and turn it to choose one of 34 scales (a quick press steps to the next one). Hold SHIFT as well to change the key. The pads now reach an octave higher. CHROMA.md
Saved with the project: the drum kits and their settings, the MIDI channel, the arpeggiator, the envelopes, the scale and the Sound Generator's sound settings now come back after you restart. Drum mode and melodic mode each keep their own arpeggiator settings. KITS_SAVE.md
SUB PAD on the Sound Generator: plays the last pad again, in melodic and drum mode. SG_SUBPAD.md
Hidden effect settings: press an FX button, then VALUE. The effect screen stays up, and each VALUE press shows the next page, including extra settings the SP normally keeps hidden (for example Tape Echo's tape distortion). Turn CTRL 1-3 to change them. Turn your volume down before you try them: some can make the sound suddenly very loud. Your edits are kept when you turn the SP off. Hold HOLD and press VALUE to switch them all off (the stock sound) and on again. FX_DEEP_EDIT.md
Faster start-up: once the project has loaded, the SP goes straight to the main screen and skips DOOM OS's start-up animation (about 4 seconds faster). BOOT_ANIM.md
Cleaner resampling: a resampled sample now starts just before its first sound, so its beginning isn't cut off.

How the build is put together, and its test status: COMBINED.md.

Synthesized kits v9.46

Thirteen kits: TR808, DR110, KPR77, Lel' UDS, FM, TR909, TR606, SDS-V, Mini Pops 7, CR78, CR8K, TR707 and TR727, every voice fitted to recordings or plug-in captures. SHIFT+PATTERN EDIT opens Kits; SHIFT+RECORD SETTING opens melodic mode. Tap SHIFT to toggle the two parameter pages. KIT selects only machines, never OFF. The modes have separate VALUE menus and share the arpeggiator. In drum mode REC records the last drums struck together (up to four within 100 ms), each to its own ring-out. All sounds are synthesized, with sixteen assignments per kit and same-machine variants marked +. These are independent models, not recovered Roland ACB. APP0 is unchanged. See KITS.md.

New in v9.46:

MIDI: sequence the kits and the melodic Sound Generator from a DAW or a hardware sequencer. Notes 36–51 play pads 1–16, the M.CH menu item sets the channel (default 16), CCs control every kit and synth parameter, and CC 120/123 stop hung notes. It works while the Sound Generator is open. Note map and CC chart.
BOUNC: write the current kit, with every pad's settings, into the sixteen pads of a sample bank. A bank that has samples asks once: FILL keeps them and fills the empty pads, OVER replaces them all, then SURE? confirms.
Drum REC length: a drum recording runs until its drums have rung out (at most 10 s). It no longer takes the melodic Pad Length, which saved only a blip when Pad Length was set to waveform cycles.
Every recording loads: the SP leaves a pad empty when its sample is shorter than 21 ms. Melodic REC with a Pad Length of a few cycles of a high enough note now becomes the fewest whole cycles that reach 21 ms, and drum recordings are never shorter.
Resample and looper: SHIFT + PATTERN EDIT opens the kits from the RESAMPLE screen while a take is armed, and from the LOOPER screen (MARK with MARK Function set to Looper). With the looper on, REC on the Sound Generator screen records the loop, in kits as in melodic.
RESAMPLE start fix: a resampled take starts on its first sound instead of keeping a few milliseconds of silence from the round trip through the effects.
Clean starts: UDS, MP-7, TR-707 and TR-727 hits start their noise filters at rest, so the same pad sounds the same every time.

Using the kits (v9.46)

Control	In drum mode
SHIFT + PATTERN EDIT	Open the kits with the last kit used
SHIFT + RECORD SETTING	Back to the melodic Sound Generator
CTRL1 / CTRL2 / CTRL3	Tune (±12 semitones) / Decay / Tone
Tap SHIFT, then CTRL1–3	Sweep / Noise / Attack; tap SHIFT again to go back
Hold a pad, turn VALUE	Step through that machine's sounds
VALUE menu	ARP, RATE, HOLD, BPM (a readout), KIT, PAD, SOUND, LEVEL, M.CH, BOUNC

Tune at 0 and the other knobs at 50 play the machine's own sound. Kit edits are saved with the project (v9.47).

Record a drum: play, press REC, pick an empty pad (it blinks), press REC again. It records the last pad you hit plus up to three others hit within 100 ms before it, each with its own timing and velocity, until the last one has rung out (21 ms to 10 s). You don't need to hold the pads.
Bounce a kit into a bank: turn VALUE to BOUNC, press VALUE, turn to a bank (A–J), press VALUE. An empty bank fills at once. A bank with samples asks FILL (keep them, fill the empty pads) or OVER (replace them all), then SURE?: NO writes nothing, YES starts. The value counts the pads and shows DONE. EXIT stops a bounce; the pads already written stay.
Resample the kits: press RESAMPLE, pick an empty pad, then SHIFT + PATTERN EDIT. The kits open with the take armed, and the first hit starts it. RESAMPLE stops it. SHIFT + RECORD SETTING on the RESAMPLE screen opens the Sound Generator as you left it.
Loop the kits: set MARK Function to Looper, press MARK, then SHIFT + PATTERN EDIT on the LOOPER screen. REC starts and stops the loop recording, and MARK goes back to the LOOPER screen. SHIFT + RECORD SETTING there opens the melodic Sound Generator.
Sequence over MIDI: set M.CH in the VALUE menu to a free channel, such as 11. Notes 36–51 play pads 1–16. Each pad has Tune, Decay and Level CCs (pads 1–4: 20–31, pads 5–12: 40–63, pads 13–16: 102–113); the last pad heard takes Tone 114, Sweep 115, Noise 116 and Attack 117. Melodic mode: TYPE 70, FREQ 71, LEVEL 72, DUTY 73, BALANCE 74, ENV 75, TUNE 76. Arp: ARP 33, RATE 34, A.OCT 35, HOLD 36. CC 123 lets go of MIDI notes and stops the arp; CC 120 also fades every voice. Full note map and CC chart.
Resampled takes start on time: in this build a take made on the RESAMPLE screen starts on its first sound. Only START moves, so you can pull it back in sample edit.

What this mod adds

Four live Sound Generator voices with shared controls and held-pad LEDs.
17 added waves: FM1:1, FM1:2, FM1:7, CZSaw, CZSqr, CZRes, Sync, Fold, Drive, LPSaw, LPSqr, Organ, Vowel, Table, Logic, Metal and Grit.
Nine timed ENV presets; four also have a resonant low-pass/filter envelope.
34 scales (27 added in v9.6): with a SCALE set, the 16 pads play only scale notes, so one bank spans two to three octaves.
An arpeggiator (v9.9.3) in the Sound Generator VALUE menu: six motifs, seven rates, octave range and HOLD, following the project or bank tempo.
MIDI IN on all four voices. When all four are busy, a new note takes one after a 2.8 ms fade-out, reducing chord-swap clicks in emulator tests.
Held-chord REC with fades at the end and when REC starts, voice stealing and fixes for release, OCT note-off, FREQ/ENV/START-END, the FREQ readout and stale TYPE selection/display.
Loudness/DC matching and quieter Pulse/Noise, while retaining raw DUTY jitter and Sync/CZRes aliasing grit. Stock waves, including Saw2, remain.
v9.6 fixes out-of-range pad releases after large OCT/ROOT/SCALE changes and FREQ bounds for wide MIDI chords. Fitting chords keep their intervals; chords wider than 84 semitones stay unchanged when FREQ is adjusted.

This does not turn normal sample pads or patterns into live synth pads. No ZEN-Core/MC-101 engine is included.

Sound Generator envelopes (v9.9.3)

In Sound Generator, select ENV and choose a preset. Play a new note after changing ENV: each voice takes its preset when the note starts. These replace the nine original non-OFF ENV shapes and work with stock and added waveforms, four-voice playback and held-chord REC.

ENV	What it does
OFF	Stock behavior; no added volume or filter envelope.
Pluck	Fast attack, short decay to silence.
Perc	Fast attack, longer decay to silence.
Keys	Fast attack, decay to a quieter held level, release tail.
Pad	Soft attack, full held level, long release.
Swell	Slower fade-in and longer release than Pad.
Bass	Fast attack with a closing resonant low-pass filter and short release.
Acid	Fast attack, stronger resonance/filter drive and very short release.
Sweep	Quick volume attack with a slowly opening resonant low-pass filter.
FPad	Soft volume attack, slow filter movement and long release.

Bass, Acid, Sweep and FPad have both volume and filter envelopes; the other five non-OFF presets shape volume only. The filter tracks note pitch. Release tails continue after note-off, while all-stop still uses the short stock fade. ENV is a preset selector, not separate ADSR/filter parameter knobs. REC renders the held chord with its selected envelope, not a live performance. See the envelope and previous v9.x notes.

Scale pads (v9.9.3)

Set SCALE to anything other than Chrom and the 16 pads play only notes of that scale, one scale step per pad, from the bottom row (lowest) to the top row (highest), left to right. Pad 9 plays the first scale note at or above its usual note. One bank then spans two octaves and a step with a 7-note scale, or three octaves with a pentatonic one. The pad lights keep their meaning (root, below and above the root). Chrom, NOTE, OCT and the other screens work as before. MIDI IN now plays all four voices, and a held MIDI note lights the pad with the same pitch.

The original scales retain their IDs. New choices include the remaining modes, blues, bebop, harmonic/melodic minor, whole tone, diminished, several pentatonics and more. Full scale list and v9.6 fixes. Added choices act as Chrom outside Sound Generator. Extreme OCT settings can put pads outside the existing playable pitch range; no new save/load persistence has been established.

Arpeggiator (v9.9.3)

Five items follow TUNE in the Sound Generator VALUE menu. Use them like the others: move to the item, enter edit, turn.

Item	Values
ARP	OFF, UP, DOWN, UP&DN, RAND, ORDER (as pressed), CHORD (all held notes each step)
RATE	1/4, 1/4T, 1/8, 1/8T, 1/16 (default), 1/16T, 1/32 of a beat
A.OCT	-3..+3: also play the held notes that many octaves below/above
HOLD	OFF, ON: latch; the next key after letting go of everything starts a new chord
BPM	Read-only: the tempo the arp plays at

With ARP on, pads and MIDI IN feed the arp instead of playing directly. Each step is released half a step later, so the ENV preset shapes every step and release tails overlap across the four voices. The arp follows the tempo BPM-synced samples in the current bank follow: the PROJECT BPM, or the bank's own BPM when the tempo is set to BANK, the MIDI clock when synced, or a playing pattern's tempo. It runs free from the first key and is not locked to the pattern's beat grid. Turning ARP on stops notes you were playing directly; leaving the Sound Generator page stops the arp. Settings are saved with the project (v9.47); a project without them starts with ARP OFF. Arpeggiator notes, build and tests.

How to install

Use this fork's web patcher, which includes the new synth options:

Open the patcher

You can also download this repository as a ZIP file (under the Code button), unzip it and open index.html in your browser. Just follow the instructions on the page.

Manual installation

Download the 5.52 system update from Roland's support page and unzip it.
Open our patcher, load the stock SP404MKII_APP1.bin and press Patch firmware. It builds Sound Generator + Kits v9.52. The patcher only accepts official 5.52 and checks the result against the fork's checksums.
Download the patched SP404MKII_APP1.bin and use it with the unchanged official 5.52 SP404MKII_APP0.bin for your test update. Back up first and keep your known-good update for rollback.
Insert the card, hold SHIFT while you turn the SP on, and press the VALUE knob when the update menu appears.
When the update is done, turn the SP off and on again.

To go back to the original firmware, just run the updater with the original Roland firmware.

Questions

I already have DOOM OS, or an older version of this mod. Can I install this? Yes. Patch the file as above, then run the normal update on your SP. Whatever your SP runs now (the original firmware, DOOM OS or an older version of this mod), the update replaces it.

Which file do I need? Roland's original firmware 5.52 update, on your computer: SP404MKII_APP1.bin and SP404MKII_APP0.bin. Load the APP1 file into the patcher. It won't take a file that is already patched, or another firmware version. Your SP doesn't need the original firmware installed first.

Will I lose my work? No. Updating the firmware doesn't erase your projects or samples, but back up before any update anyway. Projects you make with this firmware still open on the original firmware or DOOM OS; the extra settings are just ignored there. If you have a newer DOOM OS than 0.6.1, this takes you back to DOOM OS 0.6.1: your projects and samples stay, but settings or patterns from the newer DOOM OS might not carry over.

Status

v9.52 (2026-10-24) is combined-test17: v9.51 with FX deep edit test14. Hold HOLD and press VALUE to switch the hidden effect settings off and on; the edits and the switch are saved and come back after a restart; and the hidden settings come up every time, also after other screens. Its APP1 SHA-256 is e7b75421…be79. Only the FX deep edit module differs from v9.51; this exact firmware was tried on an SP-404MKII as combined-test17 before this release. COMBINED.md, FX_DEEP_EDIT.md.

v9.51 (2026-10-24) is combined-test13: v9.50 with note repeat test6. On START/END and PITCH/SPEED, ROLL does its stock job again (previewing the end of the sample, opening Groove) instead of switching the roll latch, and EXIT + pad stops that pad's roll. Its APP1 SHA-256 is 1ef31cb7…7fca. Only the note repeat module differs from v9.50; it was tried on an SP-404MKII in test builds before this release. COMBINED.md, NOTE_REPEAT.md.

v9.50 (2026-10-24) is combined-test11: v9.49 with FX deep edit test10. Hold VALUE and press EXT SOURCE, on any screen, for the input FX's hidden settings (the SP edits the input FX on its own screen, where the hidden pages never came). The combo is caught where every key press arrives, before any screen. Its APP1 SHA-256 is b7662d50…31c5. Only the FX deep edit module differs from v9.49; it was tried on an SP-404MKII in a test build before this release. COMBINED.md, FX_DEEP_EDIT.md.

v9.49 (2026-10-23) is combined-test9: v9.48 with FX deep edit test8. A user reported that CTRL 2 on the Super Filter's hidden settings spiked the volume, so all six of its hidden settings are left out. Its APP1 SHA-256 is 8f285b01…4750. Only the FX deep edit module differs from v9.48, and the change was checked in the emulator; every other module is v9.47's byte for byte. COMBINED.md, FX_DEEP_EDIT.md.

v9.48 (2026-10-23) is combined-test8: v9.47 with FX deep edit test7. A user reported that the Compressor's hidden MODE setting made the sound dangerously loud, so it is left out of the hidden effect settings; an effect without hidden settings no longer shows NO EXTRA SETTINGS. Its APP1 SHA-256 is fbcff606…e9f0. Only the FX deep edit module differs from v9.47, and the change was checked in the emulator; every other module is v9.47's byte for byte. COMBINED.md, FX_DEEP_EDIT.md.

v9.47 (2026-10-22) is combined-test7: every feature's latest test build in one APP1 (build_combined.py), plus fast boot (build_fast_boot.py) and no "SHIFT: PAGE" on the drum kit screen (build_kit_footer.py). Its APP1 SHA-256 is be758f67…34b4. Each module is byte for byte its own test build's, and the branch rebuilds the APP1 exactly. It was played on an SP-404MKII as a whole, with no bugs found, after each feature was tried on the unit in its own test builds. COMBINED.md.

Kits v9.46 (2026-10-13) is build v9.46-test3 plus the RESAMPLE start fix (APP1 SHA-256 7b5fbcb4…684a). Its test builds were played on hardware (drum REC, BOUNC and the looper), and those reports shaped the release. v9.47 carries it. Kit test status.

v9.9.3 (2026-10-07) fixes the reproduced BANK-tempo mismatch: the arp now uses the active sample bank, matching the normal TEMPO SEL screen. v9.9.2 read an independent pad-selection dialog bank, which could remain at 90 BPM.

All 71 emulator checks pass on the exact build: 21 arpeggiator checks, the 32-check v9.5 suite, 14 voice-fix checks and four new native bank-tempo checks. The new checks compare the arp with the real TEMPO SEL drawing code across all 100 active/dialog bank combinations. The build reproduces byte-for-byte; with ARP OFF it plays bit-identically to v9.6 in the emulator. Earlier builds had hardware reports confirming menu layout, step timing and PROJECT tempo. The exact v9.9.3 build is not yet hardware-tested; CPU headroom remains unmeasured. This remains experimental; four loud voices can clip. The patcher no longer offers v9.9.3 on its own: it is the Sound Generator inside Kits v9.46. APP0 stays unchanged stock.

See the arpeggiator notes, the v9.6 scale changes, the wave list and integration notes. Report synth bugs with the build, waveform, ENV preset, number of held notes and steps to reproduce. Preserve your backups and known-good firmware pair.

Disclaimer

Unofficial; not affiliated with Roland or Klangfeld Labs. Firmware modification is at your own risk. Keep your volume low when you try the hidden effect settings: some can make the sound suddenly very loud. Synth additions are by tracelistener; the underlying DOOM OS 0.6.1 ED5E base is by Quintus Oostendorp / Klangfeld Labs under the MIT License (LICENSE), retained unchanged. FX deep edit's parameter table comes from DM-404's core/fx/fxmap.json by Nicholas Petty and the dm-404 contributors, under the MIT License (THIRD-PARTY-NOTICES.md).