PM‑1 — Stage
A foot‑operated polymeter stompbox for the stage: drive it hands‑free with two heavy footswitches and an expression pedal, read it off the floor from a big RGB beat light, and run your instrument through it with the click mixed in. (For a desk/lesson unit with a full screen, see the Teacher.)
Live widget (embedded). Open the full Stage page ↗ · embed this
Designed for
Live use, hands‑free. The controls are built for feet: the left footswitch taps tempo (hold to start/stop), the right steps through your set list (hold for previous), and a 1/4″ expression‑pedal input sweeps tempo on the fly. A large RGB beat light is readable from standing height, with a small angled TFT for the BPM, item name and beat. Your instrument passes through (1/4″ in) with the click summed in the analog domain and sent to a balanced 1/4″ TRS out for the desk. Powered over USB‑C — with a second USB‑C "thru" port so several pedals daisy‑chain off one charger or power bank.
Bill of materials
Rough parts list — a foot‑operated RP2040 stompbox (USB‑C, dual‑port) with analog click injection. Ballpark one‑off prices (USD); cheaper at volume.
| Part | Qty | ~$ |
|---|---|---|
| Brain & display | ||
| RP2040 board, USB‑C — e.g. Waveshare RP2040‑Zero | 1 | 4 |
| 1.3″ IPS TFT, ST7789 — SPI; angled BPM / item readout | 1 | 6 |
| High‑bright diffused RGB beat indicator — floor‑readable | 1 | 1 |
| Controls | ||
| Heavy‑duty momentary footswitch (soft‑touch) — Tap · Next | 2 | 6 |
| 1/4″ expression‑pedal input jack (TRS) — tempo sweep | 1 | 1 |
| Audio — analog click injection | ||
| PCM5102A I²S DAC — line‑level click | 1 | 3 |
| Dual op‑amp, NE5532 / OPA2134 — hi‑Z instrument buffer + summing mixer | 1 | 1 |
| Balanced line driver, DRV134 — → 1/4″ TRS out | 1 | 4 |
| Connectors & power | ||
| 1/4″ jack — Inst In (TS) · Out (TRS) · Trig In (TS) | 3 | 3 |
| 2× USB‑C (data+power & power‑thru) + power‑path/protection + PWR LED — daisy‑chain pedals | 1 | 3 |
| Build | ||
| Custom PCB (or perfboard) | 1 | 5 |
| Passives, headers, wire — R/C for the analog stage + decoupling | — | 3 |
| Die‑cast aluminium stompbox (Hammond 1590BB‑style) — bead‑blasted, matte‑black Type II anodise, laser‑etched | 1 | 12 |
| Total (one‑off) | ≈ $52 | |
No built‑in speaker — the Stage feeds your amp / PA. The click is summed in the analog domain (hi‑Z instrument buffer + DAC → balanced line driver), so your instrument is never re‑digitised (no added latency).