Show HN: I made a tiny device for automatically recording digital pianos

Original Article ↗ Hacker News Discussion ↗

Overall reception

  • Strongly positive response; many impulsive purchases and gifts for pianists.
  • Praised as a “missing feature” that digital pianos and synths should already have.
  • Design, polish, UX, and “just works” setup repeatedly highlighted.
  • Non-musicians and non-target users still found the concept delightful and well-executed.

Core functionality & technical details

  • Records MIDI only (not audio) to an SD card; supports all MIDI messages, all 16 channels, including pedals, CCs, pitch bend, SysEx.
  • Works with both USB‑MIDI and 5‑pin DIN; acts as MIDI passthrough/thru.
  • Always-on recording with bookmarking via specific key patterns; no need to press “record.”
  • Bluetooth MIDI supported; can replace dedicated Bluetooth MIDI adapters in some setups.
  • Power draw reported around 0.3W.
  • MIDI thru latency was initially variable (5–60 ms), then optimized to ~12 ms constant; acceptable but not zero, and a splitter is suggested for ultra‑low‑latency needs.
  • Local web interface and open Wi‑Fi/BLE APIs; app is optional, recordings readable directly from SD.

Use cases & workflows

  • Main draw: removing friction compared to DAWs, laptops, and complex MIDI routing.
  • Popular for improvisation capture, practice tracking, teaching, and documenting children’s progress.
  • Use with non-piano gear (synths, drum kits, sequencers) discussed and seen as promising.
  • Some want easy MIDI export into DAWs (e.g., Ableton, Reaper); device supports both live Bluetooth MIDI and historical download.

Concerns & criticisms

  • High international shipping costs (especially to parts of EU, NZ, Australia) seen as a major barrier; suggestions for EU/UK distributors and consolidated-shipping services.
  • Some prefer pure audio recorders (Zoom/Tascam) or software-only approaches; question the need for additional hardware and an app.
  • Worries about long-term viability of the app and wireless standards; reassurances point to SD storage and open interfaces but true longevity remains uncertain.
  • Ethically, always-on recording requires informing guests; some debate over adding an “off” switch vs preserving the frictionless design.

Future features & extensions

  • Planned/desired: MIDI playback back into instruments, MIDI loops, customizable bookmarks, richer search/indexing (by chords, motifs, etc.), analytics/tutor features, and broader non-piano support.
  • Separate audio-focused product and/or audio-to-MIDI processing discussed as longer-term directions.