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Introducing the Synharmonium


Imagine an instrument that can play in perfect just intonation on any melody, in any harmonic context, in any key, with any tuning offset, with an interface that makes it dead easy to make good music. Now imagine that it can act as a midi controller for your other instruments, bringing that same great tuning and usability with it.

That is what the Synharmonium aspires to be: the beginning of a new era of music making. Or at the very least, a fun little synthesizer with a unique control scheme that you can put together yourself.

This instrument will be what you make it. That is to say, you have the oppurtunity to help design and develop it. So if you are interested and have the time, head over to our GitHub and contribute, or send us an email for other ways to help.


The Synharmonium includes aspects of the accordion, the Omnichord, and the piano to give you several easy ways to play. It has a bass keyboard like an accordion, which allows you to play any chord with a single key. From the Omnichord, it takes the strum plate, allowing you to give your chords texture. A familiar piano keyboard is included for playing melodies. With this combination, you can play solo or accompany other instruments. With USB and MIDI output, it can also be connected to a computer to control any digital or software instrument.

This instrument is programmed with an algorithm that uses just tuning to ensure that each note is mathematically related to each chord played, unlike other instruments that use equal temperament. This can always be disabled in order to accompany and play alongside other instruments.

Every part of the Synharmonium is open source. The algorithm and synthesis runs on an Arduino compatible microcontroller, which is beginner-friendly and easily modifiable. This gives any musician the ability to cater to their own needs and modify their instrument as they see fit. This also means that anyone could build their own version of the Synharmonium. An official version is in the making as a preassembled machine and a kit.

State of Development

The Synharmonium as it is pictured in the render is a long, long way away. That is a machine made up of many components; it has been decided to break the machine down into those components and develop each one or two at a time, at each stage building up a more complex and capable instrument. There will be two product releases; one at the end of the first stage of development, at which point a minimum viable product will have been created (A "Synharmonium Mini" or something like that), and a second at the end of the second stage, at which point the instrument will look more like that render, with all of the extra features needed to make it a self-sufficient solo instrument.

We'll be developing the components in roughly this order:

  1. Stradella Keyboard & Basic Midi output via MCU
  2. Tuning algorithm and MPE output
  3. Strum plate
  4. Midi throughput and Midi-MPE conversion
  5. User Interface and Hardware packaging (End of Stage 1)
  6. Piano Keyboard and relevant UI and firmware additions
  7. Onboard synthesis and relevant UI and firmware additions
  8. Hardware packaging, optimization (End of Stage 2)

We are in need of a programmer and someone with experience running an open source project, either as major contributors or someone who can be consulted as needed. If you have time to kill and find this idea as intriguing as we do, send us an email.