M5 Editor

A small browser tool for the Line 6 M5 Stompbox Modeler. It shows all 24 presets of a DUMP ALL at once, lets you rename and reorder them, shows each preset's knob settings (including the expression-pedal heel/toe range), and sends the result back to the pedal.

Use it: open M5 Editor in Chrome or Edge (Safari has no Web MIDI). Everything runs in your browser; nothing is uploaded.

What it does

• Load a DUMP ALL from a .syx file, or receive it straight from the M5 over MIDI
• See all 24 presets in two rows of 12, with the effect type and the real effect name
• Rename presets (16 characters) and swap them by dragging
• View the knobs of each preset, with heel and toe markers where the expression control moves a knob
• Save as .syx, or send all 24 presets back to the M5

Backing up and restoring the M5

• Dump: M5 MIDI OUT → interface IN. Setup page 2, Model Select to DUMP ALL?, then hold ON/OFF and press Model Select (Line 6 notes the Pilot Guide is wrong about this step).
• Restore: interface OUT → M5 MIDI IN, then just send the file. The M5 receives automatically.
• Sending a DUMP ALL replaces all 24 presets. Keep a backup.

How the format works (short version)

• 244 SysEx messages: 24 presets × 10, plus 4 for global settings
• Data is 7-bit packed (1 high-bits byte + 7 data bytes); each message ends with (length byte + data) & 0x7F
• Each preset unpacks to 1,200 bytes and starts with a checksum: the sum of all 32-bit little-endian words from byte 4 onward
• Name at byte 256 (16 chars), effect family at 334, model at 332, knob count at 336, knob values as floats from 340 (4 per knob: flag, current, heel, toe)

Not yet

• Single-preset dumps (DUMP PRE)
• Real knob names per effect
• Effect names for models not in the factory set (click the triangle to name one; it's remembered in your browser)

Credits

Made by Maurice Hissink (harmonicworks): idea, design and testing on my own M5, with Claude (Anthropic's AI) doing most of the reverse-engineering and coding from dumps I made. Built in one evening.

MIT licence.