Late 16th - Early 17th Century


Two typical Italian meantone keyboards, ca.1620-30 having 14 keys per octave through the middle register, with split keys for G/ A, and D/ E. The top keyboard at left belongs to a virginal now residing in Stockholm, Sweden. The lower is from a Florentine harpsichord of anonymous origin. Each of these keyboards also features a short octave at the lower end of its compass.

Cembalo Cromatico

A modern reconstruction of Faber's (also Fabbri, Fabri) 1631 instrument, tuned in extended meantone with 19 keys per octave, built by Denzil Wraight. Listen to a CD recording of the historical Italian cembalo cromatico repertoire performed by Christopher Stembridge.


A modern version of Nicolo Vicentino's 16th century extended meantone harpsichord, the archicembalo, having 36 keys per octave spread over two manuals, built by Marco Tiella. The top manual has 17 keys to the octave and the lower manual has 19, which are together intended to produce a tuning system of 31 unequally spaced pitches within an octave. See the literature concerning this remarkable reconstruction. A sketch of the lower keyboard design can also be found in the Vatican.

Clavemusicum Omnitonum

A single manual harpsichord having 31 keys per octave, built by Vido di Trasuntino in 1606. This instrument was apparently a reworking of an earlier instrument built in 1601 having 28 keys per octave. The earlier instrument has been compared to Zarlino's 24 key per octave harpsichord described in his Institutioni harmoniche (1558).

18th Century

A Six Rank 'All-White-Keys' Pianoforte

An instrument residing in Vienna, built by Koennicke. It would appear that this instrument is based on previous experiments of Francesco Nigetti, who built three extended meantone harpsichords sharing the name Instrumentum omnisonum in the mid 17th century.

19th Century

Enharmonic Reed Organ

According to Harry Partch, in his Genesis of a Music, this 19th century English organ built by Thomas Perronet Thompson produces 40 pitches per octave, tuned in just intonation.

Voice Harmonium

According to Harry Partch in his Genesis of a Music, this 19th century harmonium built by Colin Brown is tuned in just intonation using harmonics 24 through 48, having over 40 tones per octave.

Von Janko Keyboard

Paul Von Janko's 1875 generalized piano keyboard was not intended for microtonal purposes, but the layout has inspired similar microtonal keyboard patterns. A similar design appeared as early as 1843 as the sequential keyboard of William A.B. Lunn. The advantage of the design is that scale patterns in all keys can be played using the same fingering pattern.

Bosanquet Organ

According to Harry Partch in his Genesis of a Music, this seven-tier version of Robert H.M. Bosanquet's design allows for 53 pitches per octave. This design has been reworked in many ways, notably by the theorist Erv Wilson, whose designs have been constructed by Bob Moog, Scott Hackelman and Harvey Starr.

Play a virtual Bosanquet keyboard online at ii4i.

20th Century

Fokker Organ

Based on the theoretical work of Christian Huygens and built according to the specification of Adriaan Fokker, this 31-tone pipe organ resides in the Netherlands. A CD (samples online) featuring performances on the organ by Joop van Goozen is available from the Huygens-Fokker Foundation.

Play a virtual Fokker keyboard online at ii4i.


This 31-tone electronic organ was built as an electronic analog of the Fokker Organ.

Quarter Tone Piano

Manufactured for Ivan Wyschnegradsky by August-Foerster in 1928.

Sixth Tone Harmonium

Manufactured for Alois Hába by August-Foerster in 1927.


A just intonation keyboard by Alain Danielou.

Enharmonic Pipe Organ

This 7-limit just intonation lattice keyboard was designed by Martin Vogel for his Enharmonic Pipe Organ. Excerpts from performances on this instrument by renowned organist Hans Andre Stamm are available online.

Wilson/Daoud Keyboard

The Wilson/Daoud just intonation keyboard built by Bob Moog and Erv Wilson. The layout is a modified version of Bosanquet's design.


The Microzone is a custom programmable keyboard from Starr Labs and Erv Wilson. Another modified Bosanquet layout.

Try it out with 31ET online at ii4i.

Japanese Chromatone

A modern Japanese synth version of the Von Janko keyboard.

21st Century

Just Intonation Harpsichord

A just intonation 22 key per octave keyboard including split naturals, built in 2001 by Willard Martin for Christopher Stembridge, based on the 17th century work of Salinas and Ban.

Self-Tuning Piano from England

An invention by Geoff Smith.

Self-Tuning Piano from The USA

An invention by Don Gilmore.