Red Panda Randomizer

A randomizer and full parameter editor for the Red Panda Particle 2 granular delay, talking to the pedal directly over Web MIDI SysEx. One self-contained HTML file, no dependencies, no build step.

The point is to find sounds you wouldn't have dialled in yourself — but usable ones. A sanity control keeps rolls inside bounds derived from the pedal's own manual, and a NO LIMITS switch throws that away when you want it. Presets on the pedal are listed in a sidebar you can load, name and overwrite from.

Not affiliated with, endorsed by, or supported by Red Panda. Particle is their trademark. This is an independent tool built by reverse-engineering the SysEx protocol from the source map their web editor publishes. It only sends the same parameter and preset messages the official editor sends — it does not touch firmware. Use at your own risk; back up presets you care about before writing over slots.

Run it

Web MIDI needs a secure context, so open it over localhost (not file://):

git clone https://github.com/jeremyblanchard/RedPandaRandomizer.git
cd RedPandaRandomizer
python3 -m http.server 8731

Then open http://localhost:8731/ in Chrome, click Connect, and allow MIDI (including SysEx) when prompted. Pedal connected by USB, powered on.

Close Red Panda's own editor tab first — two pages fighting over the same MIDI port gets confusing, though it won't break anything.

Using it

Randomize (Space)	Throw away the current sound, roll every unlocked parameter from scratch
Mutate (m)	Keep the current sound and nudge every unlocked parameter by amount. Mode is held
amount	How far Mutate moves things. Boxed with Mutate because it has no effect on Randomize
sanity	How hard to keep the roll inside usable territory — see below
history ◀ ▶ ([ ])	Walk back through every roll this session and forward again
★ Bookmark	Store the current sound in this browser's Bookmarks list. Does not touch the pedal
padlock (left of each row)	Hold that parameter — Randomize and Mutate leave it alone
Sync ← Pedal	Read all current values back off the pedal
⏻ Bypass	Disengage the pedal (CC 81). Changes nothing about the sound, so re-engaging brings the same patch straight back. Follows the pedal's own footswitch

Any slider or dropdown also works as a plain editor — moving it sends immediately. Hover a parameter name for a description of what it does.

The toolbar is grouped by scope: whatever sits inside a bordered box is what the labelled control acts on. amount lives in the dashed box with Mutate because it affects Mutate alone; sanity sits in the outer box because it shapes Randomize and Mutate alike.

Randomize and Mutate are coarse and fine. Measured on the default settings, Randomize moves each parameter 36% of its range on average; Mutate at amount 25% moves it 2.7% and leaves Mode alone. Randomize to find a neighbourhood, Mutate to search inside it.

The intended loop

1. Hit Randomize (or tap Space) repeatedly while playing. Every roll goes straight to the pedal, so you hear each one immediately.
2. Something catches your ear — hit ★ Bookmark before you roll past it.
3. Roll a few more. Went one too far? history ◀ walks back through everything you rolled this session and ▶ walks forward again, so a sound is never lost to an itchy trigger finger.
4. Close but not right? Lock the parts that work — the square at the left of each row — and hit Mutate to jiggle only the rest by amount.
5. Keeper? Write to pedal puts it in a preset slot with a name.

Locks are how you steer. Lock Mode and every roll stays in one kind of sound — lock it to Delay + Rev and you get nothing but reverse patches. Lock Mode and Delay Time and you're auditioning grain and pitch behaviour over a fixed rhythmic bed; lock everything except Pitch and Detune and you're auditioning harmony.

Locking Mode also redirects the neutralisation described below, so the roll stays built around the mode you pinned rather than one it picked at random.

The sanity slider

Default 80. Uniform randomization sounds bad on this pedal for one structural reason above all others: Expert Mode is on, so every randomization source is live at once. Delay Rnd, Pitch Rnd, Detune and LFO Rate all run simultaneously no matter which Mode you picked — four sources of chaos stacked on each other. On the stock pedal the Mode switch neutralizes the ones it isn't using; in expert mode nothing does.

So the slider does two things. It narrows each parameter's range, and it neutralizes the motion parameters the chosen mode isn't about, leaving each roll with one clear idea:

Mode	is about	everything else goes neutral
Pitch + Dens	Density, Pitch	Delay Rnd 0, Pitch Rnd 0, Detune ~0, LFO off
Pitch + LFO	LFO Rate, Pitch	"
Pitch + Detune	Detune, Pitch	"
Delay + Rnd	Delay Rnd, Delay Time	"
Delay + Pitch	Pitch Rnd, Delay Time	"
Delay + Rev	Direction, Delay Time	"
Delay + LFO	LFO Rate, Delay Time	"
Delay + Dens	Density, Delay Time	"

It also snaps Pitch to consonant intervals (unison/octave/5th/4th/3rd/min7, weighted toward the first three) instead of landing between notes, and couples the note divisions — Chop is set to the same division as Delay or a shorter one, per the manual's own advice, rather than rolling independently into polyrhythmic mush.

Not every rule matters equally, so they don't all reach full strength together. One slider drives three curves:

	rules	full strength at
hard	Freeze 0, blend ceiling, feedback ceiling	40%
mid	motion neutralization, consonant pitch, Direction, Pitch Qnt	80%
soft	curated feedback modes, coupled divisions	100%

Measured over 3,000 rolls per setting: unusable rolls (freeze engaged, too wet, runaway feedback) hit 0% by 50%; mushy rolls (2+ competing motion sources, or off-key pitch) hit 0% by 80%. Variety survives — even at 100% you still get all 8 modes, 13 pitch intervals, 25 division pairings and 5 feedback modes.

At 0 it behaves as it did before. NO LIMITS overrides it entirely.

There was a character dropdown here (Ambient, Glitch, Reverse …). It is gone: sanity lerps every range toward the musical one, so at any usable sanity setting almost nothing of a character survived except which modes it allowed — and locking Mode does that more directly.

Sanity ranges

The bounds the slider pulls toward, and why:

Parameter	Musical	Reason
Blend	25–60%	dry stays at unity to 50% — keeps a dry anchor under the effect
Feedback	10–55%	recycle feedback stacks pitch and re-chops grains; runs away above this
Fdbk Tone	45–90%	dark enough to sit behind the dry, bright enough to still be heard
Chop (grain)	28–78%	very short grains give glitch tremolo and noise
Density	55–100%	high = grains overlap into a continuous sound; low = disconnected blips
Freeze	0	it's a threshold — above 0 the pedal holds a buffer instead of your playing
Delay Time	100–800 ms	of the full 0–2500 ms range
Delay Rnd	0–22%	unless the mode is Delay + Rnd, then 25–85%
Direction	100% fwd	mid values flip each grain at random; reverse belongs to Delay + Rev
Detune	5–30%	unless Pitch + Detune, then 15–70%
Pitch Rnd	0–15%	unless Delay + Pitch, then 20–65%
LFO Rate	off (noon)	unless an LFO mode, then it commits to one side rather than idling
Pan / Spread	near centre / 15–65%	full ping-pong on every grain is exhausting
Fdbk Mode	Auto, Post Delay, ±PP, Recycle, ±PP	the Repeat #/% family is inherently stuttery
Pitch Qnt	Semitones, 5th & Octave, Intervals, ±Inv	Free lands between notes

Constraints

• NO LIMITS — ignores the character and every other setting on this row. Each parameter is rolled uniformly across its whole legal range: all 8 modes, all 11 feedback modes, all 7 pitch quantizations, every note division, and 0–100% on every continuous parameter. The controls it overrides grey out so you can see it's active. Locks still apply, so you can pin one or two things and let everything else go wild.

  Two things stay fixed even here, because moving them makes a roll less varied:

  • Expert Mode stays on. With it off, the pedal resets the previous mode's parameters every time Mode changes — it would silently overwrite most of the roll the moment it landed.
  • The metaparameters are never sent. Chop/Freeze, Delay/Pitch and Param are aliases for the individual parameters, and each overwrites several of them. Leaving them out is what makes the full space reachable, not a restriction on it.

  Blend is the one exception: it never rolls below 1%, NO LIMITS included. At 0 the pedal is 100% dry, so the roll happened but none of it reaches your ears — that isn't a sound, it's a silent failure.

• max blend / max feedback — hard ceilings on the two parameters that make a roll unusable rather than interesting.

• allow freeze / drone — off by default. The Freeze parameter is a threshold; roll it high and the pedal sits on a held buffer instead of passing your playing through.

• snap pitch to semitones — quantizes the Pitch parameter to the semitone grid.

• firmware 2.2+ params — turn off for firmware < 2.2 (Pan, Spread, Fdbk Mode, Pitch Qnt didn't exist yet).

• always tempo-synced — forces musical note divisions on delay/chop/density/LFO.

Presets

The sidebar lists all 127 pedal slots, the way the official editor's Preset tab does. On connect it walks the pedal asking each slot whether it holds anything, then asks for a name for the ones that do — so the list shows real names, not just numbers.

• click a slot — number or name — to load it, which also pulls its values back into the parameter list
• ✎ renames it in the pedal's flash
• write overwrites that slot with the current sound and offers to name it
• Refresh re-walks the pedal, e.g. after saving presets from the front panel
• Backup ZIP reads every occupied slot and downloads one .syx file per preset in a dated ZIP
• Restore ZIP writes all .syx files in a backup ZIP to their original slots

The .syx files are the pedal's complete preset-data messages, byte-for-byte in the format downloaded and accepted by Red Panda's official editor. Filenames begin with the 1-based slot number so they sort in pedal order. Restore reads the destination from each file itself, confirms the affected slots, and spaces out writes to protect the pedal's MIDI/flash handling. It overwrites only those slots; presets absent from the backup are left alone.

Presets 1–4 are the front-panel ones. The first row, live, returns the pedal to its live knob settings. Overwriting an occupied preset asks first, naming what's there so you know what you're about to lose.

A numbering wrinkle

The pedal counts programs from zero: wire program 0 is the first preset, 126 is the last, and 127 is the live buffer. The manual and the front panel count presets from one, and so does this list — so preset n is MIDI program n−1, and the manual's "MIDI program 128" is wire 127.

The official editor shows the raw 0-based number in its # column, which is why its first row is 0. If you are driving the pedal from a MIDI controller, use the program number in each row's tooltip rather than the label.

Bookmarks below it are a different thing, and the distinction matters: ★ Bookmark stores a sound in this browser only, so you can shortlist a dozen candidates without burning through the pedal's 127 slots. Nothing is on the pedal until you hit write on a preset row. Clearing browser data loses the bookmarks — Export writes them to JSON.

Bypass

⏻ Bypass disengages the pedal with CC 81 rather than touching the patch, so engaging it again returns the same sound. The pedal reports its own state on CC 88 when you use the footswitch, so the button follows the pedal instead of drifting out of sync.

Bypass is not silence: your dry signal still passes through, unless the pedal's Bypass Mode is set to Kill Dry. And with Trails on, existing repeats keep decaying after it.

Notes on how it drives the pedal

Expert Mode is forced on for every roll. Outside expert mode the pedal resets the previous mode's parameters when you change Mode, which would wipe a roll. Messages are also ordered Expert → Mode → everything else for the same reason.

The three metaparameters are deliberately never randomized. Chop/Freeze (35), Delay/Pitch (36) and Param (37) are the front-panel knobs; each overwrites one or more of the individual parameters depending on mode. This tool drives the individual parameters (Chop, Freeze, Delay Time, Pitch, Detune, Density, Direction, …) directly, which is the only way to get combinations the knobs can't reach.

Protocol

Reverse-engineered from the official editor at redpandalab.com/content/apps/particle-editor/, which ships a source map — the original rpl_midi.js is recoverable from static/js/main.*.js.map. The randomizer's output was diffed byte-for-byte against it.

F0 00 02 23 <family> <product> <msgver> <type> <propHi> <propLo> <data…> F7
   00 02 23 = Red Panda manufacturer ID
   family   = 0x01, product = 0x01 (Particle), msgver = 0x00
   type     = 0x34 get · 0x35 reply · 0x36 set

Parameter values are 24-bit: trunc(value01 * 8388608) sent as four 7-bit bytes, MSB first. Property IDs with bit 0x2000 set carry a raw integer instead (mode, feedback mode, note divisions, …) rather than a normalized value.

Property IDs

Parameter	ID	CC		Parameter	ID	CC
Blend	0	12		Mode	8226	102
Chop (grain size)	1			Freeze Mode	8224
Freeze threshold	2			Delay Div	8233
Feedback	3	15		Chop Div	8234
Fdbk Tone	4	27		Density Div	8235
Delay Time	5			LFO Div	8236
Delay Rnd	6			Fdbk Mode	8238
Pitch	7			Pitch Qnt	8242
Detune	8			Expert Mode	33	119
Pitch Rnd	9			Trails	45
Density	10			Chop/Freeze (meta)	35	103
Direction	11			Delay/Pitch (meta)	36	104
LFO Rate	13			Param (meta)	37	105
Pan	20	32		Save preset	0x7F13
Spread	26	33		Program name	0x7F1C

Note divisions: 0 = off, 1–9 = 8 bars … dotted whole, 10–31 = whole note … 1/128. Delay/Chop/Density accept 0 and 10–31; LFO accepts 0 and 1–26.

Other Red Panda pedals

The repo is named broadly because the same protocol covers Red Panda's other pedals — family/product IDs and the property map differ, but the framing, the 24-bit value encoding and the 0x2000 indexed-parameter bit are shared. Adding Raster, Tensor or Bitmap means a new parameter table and a new set of musical ranges, not new plumbing. PRs welcome.

License

MIT — see LICENSE.