Isomorphic Instruments

The instruments listed here and on the websites linked below follow the principle of isomorphism, the identical or similar appearance of intervals in all transpositions. This means they are key-neutral and scale-neutral. Isomorphism is also found in many alternative notation systems.


Intuitive Instruments for Improvisers (Paul Hirsh) –  A website about isomorphic instruments, isomorphic panpipes, Janko keyboards, and more…

Keyboards, Accordions, Button Instruments

Generalized keyboard, a predecessor of the Janko keyboard that accommodates microtonal tunings (invented by R. H. M. Bosanquet, extended by Erv Wilson and others) – ,

Janko Keyboard Layout with two whole tone scale rows

Daskin brand Janko Keyboards (Paul Vandervoort) –

Lippens keyboard derived from Janko’s design

Chromatone brand Janko-style keyboards (Japanese company) –

Chromatone Lite for iPad –

Dodeka Keyboard –

The Balanced Keyboard (Bart Willemse) –

Chromatic Button Accordions –

C-thru music’s “Axis” instruments using the isomorphic harmonic table note layout – ,

Wicki-Hayden Note Layout

Musix for iPad – One of the layouts is the Wicki-Hayden.

AltKeyboards website on isomorphic keyboards, focusing on the Wicki-Hayden note layout (Ken Rushton) –

The DIY Keyboard Project (Drew Wagner) –  Focuses on building alternative, isomorphic keyboards. It is an open-source hardware development project with the goal of making all of the CAD files, microcontroller code, etc. necessary for a hobbyist to build a digital keyboard freely available.

6-6 Colored Traditional (7-5) Keyboard (on this wiki)


Isomorphic Saxophones and Flutes (Jim Schmidt) –

String Instruments

Many traditional string instruments are isomorphic in their usual tunings (violin, viola, cello, double bass, mandolin, bass guitar). The guitar is mostly isomorphic in its usual tuning, with the exception being the major third between the G and B strings. Some people tune the guitar with all neighboring strings a major third apart, or all a perfect fourth apart, making the tuning completely isomorphic. Wikipedia page on regular tunings for guitar

The Harpejji, an alternative, isomorphic string instrument (like a combination of a Janko keyboard and an electric guitar) – Page

Chromatic harp – (Page in German)


Isomorphic Vibraphone with a Janko-style layout, and three-color pattern (Roy Pertchik) – see Tri-Chromatic Keyboard Pattern