SP-404 MKII+P-6·COMPANION
A touchscreen brain for your grooveboxes.
Compa is a Raspberry Pi app that gives the Roland SP-404 MKII and P-6 a real screen. Live FX and granular control, chromatic MIDI keyboard, recording with recall buffer, and a full kit-build pipeline that exports to Akai MPC, Akai Force, and Ableton Live.
Runs on
Pi 3B+ and up
Status
Free, open source
License
MIT
Record → Slice → Build → Push
One workflow, four stops.
Compa connects the whole beat-making loop — from capturing a sound on the box, to landing it inside your DAW — without leaving the touchscreen.
01
Record
Capture audio from any connected device. 60-second recall buffer — forgot to hit record, you still got it.
02
Slice
Visual waveform slicer with auto-detect. Place markers by ear or let Compa find the transients.
03
Build
Drop slices onto a 128-pad grid across 8 banks. Preview, rearrange, name.
04
Push
Export to Akai MPC (.xpm), Akai Force, or Ableton Live (.adg). Push over USB or the network.
SP-404 MKII Workspace
Live FX in the orange.
Compa mirrors the SP-404's 5-bus architecture — Bus 1–4 plus Input FX — with full knob control, per-bus FX chain editing, and a Twister grid that lets you slam effects from 16 knobs with color feedback. The sequencer, looper, and DJ mode are all right there.
P-6 Workspace
Granular without the menu-diving.
The P-6's granular engine is the reason you bought it, but the hardware interface makes tweaking it a chore. Compa gives you the full 14-parameter engine on one screen, pattern selection without scrolling, and a chromatic keyboard that plays your current pad across two octaves.
MIDI controller support
Plug in any MIDI keyboard. Plug in a Twister. Compa adapts.
Compa auto-detects any USB MIDI device within 2 seconds. Known controllers get deep integrations — the Midi Fighter Twister, ATOM SQ, and Spectra all have dedicated routing. Everything else is treated as a chromatic keyboard that plays the focused device melodically.
Midi Fighter Twister — SP-404 page
K1
To-Gu-Ro
K2
Scatter
K3
Tape Echo
K4
Ko-Da-Ma
K5
Downer
K6
Ha-Dou
K7
Zan-Zou
K8
Stopper
K9
Reverb
K10
Vinyl Sim
K11
Crusher
K12
Filter+Drive
K13
JUNO Chorus
K14
Cassette
K15
Isolator
K16
Flanger
Press a knob → load that FX on the bus. Turn → sweep the effect. LED color = effect family. Switch to P-6 and the same 16 knobs now control the granular engine.
Midi Fighter Twister — P-6 page
K1
Position
K2
Size
K3
Density
K4
Pitch
K5
Spray
K6
Reverse
K7
Freeze
K8
Filter Cutoff
K9
Filter Reso
K10
Envelope A
K11
Envelope D
K12
LFO Rate
K13
LFO Depth
K14
Pan
K15
dynamic
K16
dynamic
14 knobs for the full granular engine, 2 dynamic slots that adapt per screen. Every tweak sends CC on the P-6's Auto channel, so it's captured as automation.
Chromatic keyboard
Two-octave range, pad selector across all banks, LATCH mode, octave shift ±3, touch-to-play when no keyboard is plugged in. The blue key marks the sample's natural pitch. Routes to SP-404 Ch16 or P-6 Ch4 based on focus.
Everything on the box
Real features. Already in the repo.
Chromatic keyboard
Plug in any USB MIDI keyboard — Alesis, Arturia, AKAI, Novation. Play any SP-404 pad or P-6 sample melodically across two octaves with a visual piano, latch mode, octave shift, and touch-to-play.
Midi Fighter Twister
Deep integration. 16 knobs with RGB feedback — SP-404 FX slots on one page, P-6 granular parameters on another. Press to activate, turn to sweep. Auto-retargets when you switch focus.
Recording & recall
Every take from every connected device lands in one browser. 60-second recall buffer grabs the last minute even if you forgot to hit record. BPM auto-detect, threshold recording, star/rename/delete.
Kit builder + export
128 pads across 8 banks. Drag samples on, preview, rearrange, export. Targets Akai MPC (.xpm), Akai Force, and Ableton Live (.adg). Smart auto-import from slice markers.
Internet radio capture
Built-in browser for 90+ curated stations — jazz, lo-fi, hip-hop, ambient, world. Route the stream into any connected device for instant resampling.
Network transfer
Compa-to-Compa peer discovery over mDNS. Send recordings, kits, or samples between Compas on the same LAN without cables. SMB share for Mac/PC too.
Every screen · Real UI
What you actually see on the Pi.
Captured directly from the app. No placeholder mockups — this is what Compa looks like when you're using it.
Free · MIT · Community driven
Flash an SD card. Plug in. Ship.
Compa OS is a complete Raspberry Pi image — Pi OS Lite plus the Compa app, autostarting on first boot. Grab the latest build below, write it to an SD card with Raspberry Pi Imager, and you're live.
~720 MB compressed (~4–5 GB on the card). Boots on Pi 3B and up. Manual install path (existing Pi OS) is in the README.