pi-multifx-pedal/docs/test-plan-focusrite.md

Pi Multi-FX Pedal — Focusrite 2i2 Test Plan

Prototype validation before ordering I2S HAT boards. Tests the complete software stack — DSP, 4CM routing, NAM, FX, Web UI — with hardware you already own.

Wiring

Mono Mode (Standard Pedal)

Guitar → Focusrite Input 1 (front)
Focusrite Output 1 (rear) → Amp or Audio Interface

4CM Mode (Four Cable Method)

Guitar → Focusrite Input 1 (front)         ← ADC ch0
Amp FX Send → Focusrite Input 2 (front)    ← ADC ch1

Focusrite Output 1 (rear) → Amp Input       ← DAC ch0 (Send / pre-amp)
Focusrite Output 2 (rear) → Amp FX Return   ← DAC ch1 (Output / post-amp)

Config

Edit ~/.pedal/config.yaml on the RPi. Two profiles:

config-mono.yaml — Standard pedal test

audio:
  mode: mono
  hat_type: focusrite
  input_device: "hw:1,0"
  output_device: "hw:1,0"
  jack_enabled: true
  auto_connect: true
  profile: standard

presets:
  dir: "~/.pedal/presets"
  install_factory: true

config-4cm.yaml — 4CM stereo test

audio:
  mode: stereo_4cm
  hat_type: focusrite
  input_device: "hw:1,0"
  output_device: "hw:1,0"
  jack_enabled: true
  auto_connect: true
  profile: standard

presets:
  dir: "~/.pedal/presets"
  install_factory: true

Test Sequence

Phase 1 — Mono Mode (Basic Signal Chain)

#	Step	Expected	Check
1	SSH into RPi: ssh pi@pedal.local	Connected	✅
2	Wire guitar → Focusrite Input 1, Output 1 → amp	Physical	✅
3	Start pedal: python3 main.py --config ~/.pedal/config-mono.yaml	Boots, JACK starts	✅
4	Play guitar	Sound through amp, clean bypass	✅
5	Open browser to http://pedal.local:8080	Web UI shows dashboard	✅
6	Click bypass toggle on web UI	Pedal mutes → unmutes	✅
7	Check preset name shows on dashboard	"Default" or first preset	✅
8	Press preset up/down on footswitch or web UI	Changes preset, different sound	✅

Phase 2 — FX Block Tests (Mono)

#	Step	Expected	Check
1	From web UI, open a preset or start fresh	Chain visible on dashboard	✅
2	Toggle Noise Gate on/off	Noise floor drops when active	✅
3	Adjust compressor threshold	Compression amount changes	✅
4	Turn on Overdrive, adjust drive slider	Distortion increases	✅
5	Try Distortion, Fuzz	Different clipping textures	✅
6	Load a NAM .nam file via Models page → Upload	Model loads	✅
7	Enable NAM block	Amp-modeled sound from uploaded model	✅
8	Load an IR .wav file via IRs page → Upload	IR loads	✅
9	Enable IR block (after NAM in chain)	Cabinet sound	✅
10	Try Delay, adjust time + feedback	Echoes	✅
11	Try Reverb, adjust size + decay	Room sound	✅
12	Try Chorus, Flanger, Phaser	Modulation effects	✅
13	Try Tremolo, Vibrato	LFO-based FX	✅
14	Try EQ — boost/cut lows, mids, highs	Tone shaping	✅
15	Try Octaver — play on low E string	Sub-octave follows playing	✅
16	Try Bitcrusher — reduce bits	Lo-fi digital artifact	✅
17	Try Ring Modulator	Metallic bell-like tones	✅
18	Try Ping-pong Delay (stereo output)	Alternates left-right	⚠️ Needs stereo monitoring

Phase 3 — New FX (Full Palette)

#	Step	Expected	Check
1	Auto-Wah — play with pick attack	Filter sweeps with playing dynamics	✅
2	Envelope Filter	Similar to auto-wah, different curve	✅
3	Expander — set low threshold	Quiet parts get quieter	✅
4	De-esser — set freq to ~6kHz	Sibilance reduced	✅
5	Transient Shaper — boost attack	Picking attack pops more	✅
6	Wavefolder — increase fold	Harmonic saturation	✅
7	Rectifier — full wave	Octave-up fuzz	✅
8	Parametric EQ — boost 800Hz +3dB	Mid bump	✅
9	High-Pass Filter — sweep up	Low end cuts off	✅
10	Low-Pass Filter — sweep down	High end rolls off	✅
11	Formant Filter — cycle vowels	Vowel sounds (aaa-eee-iii-ooo-uuu)	✅
12	Multi-tap Delay — try triplet pattern	Rhythmic repeats	✅
13	Reverse Delay	Played-backward effect	✅
14	Tape Echo — increase wow	Wobbly vintage echo	✅
15	Rotary Speaker — slow/fast	Leslie cabinet swirl	✅
16	Uni-Vibe — adjust rate	Hendrix-style phaser	✅
17	Auto-Pan — stereo output	Moves left-right	⚠️ Needs stereo
18	Stereo Widener	Bigger stereo image	⚠️ Needs stereo
19	Detune — short delay time 0.5-3ms	Thickened, chorus-like	✅
20	Whammy — sweep pitch bend	Pitched expression	✅
21	Early Reflections	Small room ambience	✅
22	Shimmer Reverb — add shift	Ethereal, pitch-shifted reverb	⚠️ BETA - watch for xruns

Phase 4 — 4CM Mode

#	Step	Expected	Check
1	Wire per 4CM diagram above		✅
2	Switch config to config-4cm.yaml		✅
3	Start pedal: python3 main.py --config ~/.pedal/config-4cm.yaml	Boots with 2ch I/O	✅
4	Open web UI → Settings → toggle 4CM ON	Routing badge shows "4CM"	✅
5	Verify: guitar input goes through pre blocks only	Pre effects (gate/comp/drive/NAM/IR) through Send	✅
6	Verify: return input goes through post blocks only	Post effects (mod/delay/verb) through Output	✅
7	Adjust breakpoint slider	Moves which blocks are pre vs post	✅
8	Disable 4CM → back to mono	Full chain, no split	✅
9	Save preset with 4CM routing	Reload — routing preserved	✅

Phase 5 — Presets & State

#	Step	Expected	Check
1	Create new preset via web UI	Saved	✅
2	Name it, set FX chain, save	Round-trips	✅
3	Load preset — verify all params restored		✅
4	Delete preset	Removed from list	✅
5	Save a preset in 4CM mode	routing_mode saved	✅
6	Restart pedal — last preset restores	State persistence	✅

Phase 6 — MIDI (optional, needs MIDI controller)

#	Step	Expected	Check
1	Connect MIDI controller via USB	MIDI LED on controller?	✅
2	Send Program Change 0-3	Switches presets	✅
3	Assign expression pedal (CC 11) → volume	Volume follows pedal	✅
4	MIDI Learn: CC → parameter	Parameter controllable via MIDI	✅

Phase 7 — Performance / Stability

#	Step	Expected	Check
1	Play for 30 min straight	No xruns, no crackle	✅
2	Switch presets rapidly 20x	No crash	✅
3	Toggle bypass rapidly 20x	No crash	✅
4	Load heavy preset (NAM + IR + delay + reverb + chorus)	CPU stable, <80% load	✅
5	Check CPU: top or htop	< 70% on RPi 4B	✅
6	Check JACK xruns: cat /proc/asound/card0/pcm0p/sub0/status | grep xruns	0 xruns	✅
7	Cycle power — pedal boots to last state		✅

Known Limitations (BETA FX)

These effects were tagged as CPU-heavy — test on your rig and report xruns:

Effect	Risk	Mitigation
Shimmer Reverb	High — pitch shift + re-verb loop	Increase JACK period to 256 frames
Pitch Shifter	Medium — overlap-add granular	Keep shift < 3 semitones
Looper	Medium — large buffer (~6MB)	Not yet implemented — stub only

Reporting Issues

If an effect doesn't sound right or causes xruns:

1. Note which effect + parameter settings
2. Check /var/log/pedal.log for errors
3. Run hermes kanban --board pi-multifx-pedal create "Fix: [effect name] — [issue]" and I'll handle it