HMMM
A drone machine for the CHOMPI, after the SOMA Lyra-8.
It has eight voices. Each is a triangle that SHARP bends towards a square.
- Pairs and groups: the voices are tuned by ear, and arranged in four pairs (12 34 56 78) and two groups (1234 5678).
- FM: pairs can frequency-modulate each other in a ring, or be modulated by the Hyper LFO. With TOTAL FB on, the instrument's own output modulates them.
- Signal chain: everything runs into a two-line modulated delay that can sing by itself, then a fuzz.
Beta. Download from Releases.
Controls
CHOMPI is shift.
| Do | Does |
|---|---|
| White keys 1–8 | The eight voices: hold to sound |
| LOOP | Latch: tap a voice on, tap it off |
| PLAY | TOTAL FB on/off |
| Toggle switch | FM ring: up = one big loop, down = two loops (12↔34, 56↔78) |
| Big purple knob | Delay feedback (CHOMPI: delay mix). It turns white once the delay sings by itself |
| Volume knob | Volume (CHOMPI: distortion drive). Click: everything off |
| CHOMPI + black key | Page |
| CHOMPI + white key | Load patch 1–15. Hold 1 s to save |
| CHOMPI + PLAY / LOOP | Octave down / up |
| CHOMPI + click a knob | Reset it |
Pages
Italics = CHOMPI + turn.
| # | Page | Knob 1 | Knob 2 | Knob 3 | Knob 4 |
|---|---|---|---|---|---|
| 1 | TUNE 1–4 | voice 1 | voice 2 | voice 3 | voice 4 |
| 2 | TUNE 5–8 | voice 5 | voice 6 | voice 7 | voice 8 |
| 3 | SHARP | pair 12 FAST 12 | pair 34 FAST 34 | pair 56 FAST 56 | pair 78 FAST 78 |
| 4 | MOD | depth 12 source 12 | depth 34 source 34 | depth 56 source 56 | depth 78 source 78 |
| 5 | GROUPS | HOLD 1234 vibrato | HOLD 5678 | PITCH 1234 | PITCH 5678 |
| 6 | HYPER LFO | freq A | freq B | OR / AND | LINK |
| 7 | DELAY | mix mod 1 | time 1 mod 2 | time 2 SELF / LFO | feedback TRI / SQUARE |
| 8 | DISTORTION | drive | mix | ||
| 9 | VOICE | attack | release | character | stereo spread |
| 10 | TUNE | octave | transpose | fine | MIDI bend range |
Notes on the pages:
- Voice TUNE knobs: a plain turn moves 2 cents a click, and fast turns move further. CHOMPI + turn moves in whole semitones. Each voice covers ±1 octave around its home note: voices 1–2 low, 3–6 middle, 7–8 high.
- MOD source: off / FM (the neighbouring pair in the ring) / LFO (the Hyper LFO, or the whole output when TOTAL FB is on).
Building
cd code/src
PATH=/path/to/gcc-arm-none-eabi-10.3-2021.10/bin:$PATH make
build/CHOMPI.bin ships as HMMM.bin.
Desktop harness: make -C host && host/render host/out.
Credits
By hiwatts (@sfaber02). The hardware layer comes from CHOMPI Club's open-source firmware (MIT); see LICENSE.chompi-club. Not affiliated with SOMA Laboratory: HMMM is an homage, not a clone of their circuit.