Tonnetz is a two dimensional arrangement of musical pitches, first discovered by Euler. One of it's special properties, is the fact that specific harmonies always retain their geometric shape, regardless of which key they are played in.
First commercial product to apply the principle was probably the Opal Sonome keyboard, but in recent years (somewhere after 2008) the C-Thru Axis appears to have become synonimous with the technique. This is the first QWERTY keyboard incarnation.
- It costs nothing
- Plays sounds with WebAudio API
- Mirrors the current chord on a traditional piano keyboard
- Clicking a piano key reflects it on the keyboard
- Send out MIDI
- Recording and playback