nux-lite-ctl

Native Linux control for the NUX Mighty Lite BT MkII (NGA-3BT) guitar amp over USB-MIDI SysEx — no Wine, no Bluetooth, no vendor app.

The official Mighty app is mobile-only and talks BLE. The amp also has a USB port that shows up as a class-compliant USB-MIDI device (1fc9:8260, NXP), so everything the app does can be done from a shell with ALSA's amidi. This repo is the result of reverse-engineering that path and verifying it against real hardware.

Setup

Python 3 and amidi (package alsa-utils on Arch/Debian). No pip installs.

$ aplay -l           # nothing needed from PipeWire/JACK — raw ALSA MIDI
$ python nuxctl.py ports
NUX amp on hw:2,0,0

Commands

Command	What it does
ports	Find the amp's raw-MIDI port
dump [slot]	Decode and print presets (all 7 slots, or one)
backup	Dump all 7 presets to presets-backup.json
select <1-7>	Switch the active preset slot
apply <song.json> <tone>	Push a tone spec into the live buffer (audition only)
commit <1-7>	Write the live buffer to flash — permanent, no undo
tuner [seconds]	Run the amp's tuner with terminal readout

apply / commit are deliberately two steps: a tone is always auditioned before it becomes permanent, because the amp has no per-slot factory restore. (For exactly that reason, presets-factory-20260729.json is a dump of the factory presets — the restore point NUX doesn't give you.)

$ python nuxctl.py apply songs/deftones-change.json verse_dark
Applied 'verse_dark' from Deftones - Change (In the House of Flies)
  -> LIVE buffer only. Nothing written to flash.
  -> Switch slots and back to discard it.

Song tone files

songs/ holds annotated tone recipes (Deftones ×4, Nirvana). They're not just parameter dumps — each tone documents why every setting is what it is (amp-model choice per era, when the chorus effect is identity vs. atmosphere, tuning notes across a setlist so nothing needs a retune between songs):

"verse_dark": {
  "_comment": "Treble at 40 is the point - the darkest clean in any of the song files. ...",
  "amp": 2,
  "amp_params": [32, 60, 52, 46, 40],
  "_amp_params_are": "Deluxe Rvb: Gain, Master, Bass, Middle, Treble",
  ...
}

Protocol notes

Derived from tuntorius/mightier_amp (the excellent open-source replacement for the Mighty app) and verified against hardware. Messages are plain MIDI SysEx:

Constant	Value	Meaning
header	F0 43 58	SysEx start + C X (Cherub/NUX vendor bytes)
direction	00 / 01 / 02	GET / SET / REQ
MSG_PRESET	0x0B	Read/write a preset slot
MSG_CURPRESET	0x0C	Current-slot operations
MSG_SPEC_CMD	0x75	Special commands (e.g. 48 = save live buffer)
MSG_TUNER	0x6F	Tuner stream on/off

Hard-won gotchas, so you don't lose the hours I did:

1. USB is not BLE. The mobile app wraps every message in BLE-MIDI packet framing — 80 80 before F0, 80 before F7. Over USB-MIDI those bytes are not part of the message; ALSA handles packetisation. Send them raw and the amp silently ignores you. Emit bare F0 .. F7.
2. Saves that lie. The save command lives on 0x75 (MSG_SPEC_CMD), not 0x15 (kSYX_CURSTATE). The amp ignores 0x15 without erroring, so saves appear to succeed and nothing is written.
3. Live buffer vs flash. Edits are CCs into a volatile live buffer; flash is only touched by the explicit save command. That's what makes the audition-then-commit workflow possible (and safe).
4. Tuner modes lie about non-standard tunings. guitarStandard snaps readings to E standard and will misreport a Drop C# low string — chromatic is the only trustworthy mode if you don't play in standard. The tuner command defaults to a Drop C# target; edit DROP_CSHARP for yours.

compare-tone.py

"It doesn't sound the same" as a measurement instead of an argument: records the amp (or takes two WAV files) and compares octave-band energy balance, normalised for overall level, against a reference recording.

python compare-tone.py record [seconds]     # capture from the amp, then compare
python compare-tone.py compare A.wav B.wav  # compare two existing files

License

MIT. Protocol knowledge builds on tuntorius/mightier_amp — if you want full-featured control of a Mighty-series amp on mobile, use that project.