open-source hybrid piano

Description

A hybrid digital piano combines the physical action of an acoustic piano with MIDI, sound generation, and other features of a digital keyboard. Kawai and Yamaha sell hybrid pianos. A few years back I decided to build my own. With a custom hybrid, I can use any piano action and even install it as a piano silent system. It gives me complete control over my piano’s features and performance. The boards and sensors could also be used to invent new musical instruments. The project started in 2020. I experimented with several architectures and its presently on third iteration. Everything to build a fully functional piano is on GitHub, although it needs a separate piano action. Related project references are listed on GitHub. Repositories: https://github.com/gzweigle/open-hybrid-piano https://github.com/stem-piano Historical short videos after each milestone: https://www.youtube.com/@gzpiano88

Project Logs

Collapse

completed 176 sensors on the open source hybrid piano
Greg Zweigle • 06/01/2025 at 17:45 • 0 comments

Now have 88 hammer sensors + 88 damper sensors.
Also fixed bugs with integration of hammer and damper sensor data.
Its a milestone and sets the piano up for the next stage of project.
Project History Log
Greg Zweigle • 05/03/2025 at 11:29 • 0 comments

May 2, 2025 - New Sensors

Convert all piano hammer position sensors to the latest hardware design.

November 29, 2024 - First Independent Build

A second open-hybrid-piano, directly from GitHub artifacts. Independent validation I got everything pushed to GitHub correctly.

April 21, 2024 - Accuracy Improvement Improve note-to-note consistency.

Eliminate trimming resistors (see above: continued to use many of old sensors until May 2, 2025).

November 26, 2023 - Open Source Hybrid Piano, Digital Architecture

Finished pushing all files to the repository.

November 10, 2023 - Finish "Stem Piano G"

First time a full 88 key piano with the simpler architecture is functional. This is the architecture on GitHub on Nov 26, 2023 and documented on GitHub.

March 16, 2023 - First 88 Key Piano

First time my full 88 key piano is functional, including pedals. Built from a mix of two architectures. Neither of these designs is presently in use. But they remain interesting for future development.

March 7, 2023 - Single Board Architecture

First piano subset for the single board architecture.

January 15, 2023 - Pedals First working with three pedals.

July 8, 2022 - High Performance Architecture

First piano subset with the high performance architecture. Expensive and complex.

January 2, 2022 - Started Open Source

Created repository.

July 24, 2021 - Eight Piano Keys

My first working piano with more than one note.

June 11, 2021 - First Datapath

Full data path is functional, one note.

December 5, 2020 - Start Project