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Pianos, harpsichords and organs are suited for microtonal music insofar as the strings/pipes can, within limits, be tuned to anything desired. The probability that tuning issues arise with these instruments is even slightly higher than average since there is often "old" music (baroque and older, from the pre-well-tempered age) being played on them.

For electronic instruments (synthesizers), there is, in theory, absolute freedom for the pitches anyway — not in practice, though. But nowadays, many synthesizers have a built-in retuning functionality.

A potential source for troubles is the traditional keyboard design, the Halberstadt keyboard, which is optimized for diatonic scales and 12 tones per octave. For microtonal music with not more than 12 tones per octave, this is not such a problem — fingerings for non-standard scales can be learned. But it can become a problem if you need more than 12 tones per octave, or even want a nonoctave tuning, such as Bohlen-Pierce or one of Wendy Carlos's equal-step scales. Fortunately, there exist several solutions to this problem.

Strategies for more than 12 tones per octave

Multiple keyboards

One solution is to use several keyboards whose keys are slightly detuned against each other. This solution was namely used by several classical composers in the 20th century, including Alois Hába, Charles Ives and Ivan Wyschnegradsky, usually with a 12edo tuning on each keyboard, but with different reference pitches. 24edo can be achieved by tuning two keyboards a quarter tone apart from each other, 36edo by tuning three keyboards separated by sixth tones, and so on.

Of course, each keyboard's tuning does not have to be 12edo, but choosing a 12-tone octave-repeating scale has its advantages. The keyboard layout keeps the familiar property that 12 key steps span one octave, and the pitches typically need only minor retuning. This is not unimportant for acoustical instruments, where we usually have physical limits to the amount a pitch can be retuned. For this reason, this approach is widely used, especially in the field of contemporary classical music. As for synthesizers, a compatibility list for various models can be found at Microtonal Synthesis.

The main disadvantage of this solution is, of course, that you need several keyboards. In the case of acoustic pianos, this means in practice that the maximal number of pitches per octave you can obtain is limited - to the number of pianos you can put on the stage together... Arc-en-ciel by Ivan Wyschnegradsky, for example, a piece in 72edo, is written for six (!) pianos, and [ "Limited approximations" by Georg Friedrich Haas, in 72edo as well, needs the same number of pianos and moreover a whole orchestra...

Electronic keyboards sometimes have the possibility to play in "split" mode, i.e. the upper and the lower half of the keyboard can send to different midi channels. Some keyboards offer up to 4 split areas. In this case, you need only one keyboard - but you still have the disadvantage of having to jump between the areas.

Full keyboard retuning

Tune each key of the keyboard to a different pitch. The pitches of the keys keep the property of being arranged in ascending order, but the octave pattern will be different, and there are larger amounts of retuning required. In addition, this method usually reduces the interval size you can play with a single hand, because pitches are more spaced out.

Some synthesizers support full keyboard retuning, but not all. A compatibility list for various models can be found at Microtonal Synthesis. Synthesizers supporting only 12-tone octave-repeating scales can be brought to support full keyboard scales with the help of the Midi Integrator software, or the alt-tuner software. Some virtual instruments, such as PianoTeq, also provide support for full keyboard retuning regardless of the physical controller used with it.

A possible "full keyboard scales" piano tuning for 22edo, mapping two keyboard octaves to one acoustic octave, is described in Paul Erlich's paper on 22edo, on page 11.

In the case of acoustic instruments such as pianos, tuning full keyboard scales may even require major changes in construction. It has been done, however, to build instruments such as 96edo pianos.

Modulation wheel

Synthesizers, even without retuning functionality, often have a special functionality that is principally also suited for microtonality: the modulation wheel. Here are a few impressive examples of how to make microtonal music with the modulation wheel:

This is, however, not a particularly easy way to do it...

Dynamic tunings

Some instruments allows their tuning to be changed "on the fly", allowing access to more than 12 notes, although not all at once. The main advantage is that the keyboard layout keeps the familiar property that 12 key steps span one octave. The main disadvantages is that certain melodies will be unplayable, such as a rapid passage using more than 12 notes.

For example, the Turkish kanun is a diatonic instrument like a hammer dulcimer, but plucked, not struck. Each set of strings has a set of mandals, a tiny lever which when flipped changes the length of the string and microtonally changes the pitch. It's analogous to the sharpening levers on the celtic harp, but there are mote than one lever per string, and they sharpen considerably less than a semitone.

The easiest way to experiment with dynamic tunings is with midi keyboards and software. Scala and Lil' Miss Scale Oven have limited dynamic tuning ability. Alt-tuner allows retuning of individual notes (choosing among various ratios or among various EDO degrees), modulating to different keys (either by a specific interval, or to a specific note, or to the current bass note), and switching to completely different tunings. All this can be done via keyswitches, foot pedals, the mod wheel, or any control that generates a midi signal. These midi signals can come from any midi device, such as a 2nd keyboard, or even the computer's QWERTY keyboard. Technique-wise, using keyswitches would be similar to using mandals or sharpening levers, and using footpedals would be similar to using the classical harp's pedals.

Alternative keyboards

English Wikipedia has an article on:
English Wikipedia has an article on:

This is actually quite an old idea, since in many historical temperaments, there was a demand for differing between flats and sharps. Minor variations to the common Halberstadt layout, sometimes known as an enharmonic keyboard, have been used to accommodate extra keys for such purposes, such as split sharp keys. Denzil Wraight's website has some beautiful examples of historical harpsichords with up to 24 keys per octave. A list of existing church organs all over the world with split semitone keys can be found on Ibo Ortgies' homepage.

In modern times, the idea of alternative keyboards has come up again. Most alternative keyboard layouts can host the same fingering for multiple tunings, since most of them have been designed with 12edo in mind and can be generalized using the corresponding diatonic intervals. Many alternative keyboards are isomorphic keyboards, which allow layouts where each interval or chord has the same shape in every key. Any layout may be arranged in multiple ways on an actual instrument by changing the orientation of the layout, the number of keys, the angle between the axes, the key colors, etc.

Isomorphic keyboard layouts
Layout Tiling 1st axis 2nd axis Complementary axis
Bosanquet/Jankó Hexagonal Major 2nd Minor 2nd Augmented 1sn
Harmonic table Hexagonal Perfect 5th Major 3rd Minor 3rd
Wicki-Hayden Hexagonal Perfect 5th Major 2nd Perfect 4th
Chromatic accordion (types B/C) Hexagonal Minor 3rd Major 2nd Minor 2nd
Array mbira Hexagonal-ish Perfect 8ve Perfect 5th Perfect 4th

Another way to generalize the Halberstadt layout is to use a different MOS scale to determine the layout of white and black keys. Stephen Weigel has used such layouts in several of his YouTube videos, including hanson (4L 3s) and porcupine (7L 1s) layout for 15edo, mavila (7L 2s) layout for 16edo, etc.

For electronic music, there is meanwhile a number of generalized keyboards that are available or are soon to be available, see following list.

List of synthesizers with alternative keyboards

Generalized keyboards

Product Manufacturer Layout No. of keys Availability Price
Thummer Thumtronics Wicki-Hayden 114 Never produced
Tonal Plexus U-PLEX, TPX2, TPX2s Hπ Instruments Square tiling, 17\205 × 1\205 422 No longer produced (as of 2014)
Tonal Plexus TPX4 Hπ Instruments Square tiling, 17\205 × 1\205 844 No longer produced (as of 2014)
Tonal Plexus TPX6, TPX6s Hπ Instruments Square tiling, 17\205 × 1\205 1266 No longer produced (as of 2014)
MiniMod Hπ Instruments Various (hexagonal, rectangular, 1-dimensional et al.) XXX XXX
AXiS-49 C-Thru Music Harmonic table 98 No longer produced
AXiS-64 C-Thru Music Harmonic table 192 No longer produced
Opal Chameleon, Opal Gekko Opal Harmonic table 192
monome grid monome Square tiling, mapping by coordinates (no default mapping) 128 (formerly 64, 128 or 256) In production $600
Lippens Keyboard Lippens Jankó 198 Prototype
Daskin 5 Daskin Manufacturing Jankó 203
Daskin 6 Daskin Manufacturing Jankó 243
Vertical keyboard (Elaine Walker) Elaine Walker 1-dimensional, 2 tiers of keys (black/white), with customizable black/white pattern 61, 76 or 88
Metatonal Keyboard Metatonal Music (Ron Sword) 1-dimensional, 2 tiers of keys (black/white), with customizable black/white pattern Never produced
Lumatone / Terpstra keyboard Cortex design Hexagonal tiling, customizable layout (default: Bosanquet) 280 In production $3,999
ZBoard 24×24 Starr Labs Square tiling, customizable layout (default: perfect 4th × semitone) 576 In production $7,995
ZBoard 12x24 Starr Labs Square tiling, customizable layout (default: perfect 4th × semitone) 288 In production $3,495
Microzone U-648 Starr Labs Bosanquet 288 In production $3,495
Microzone U-990 Starr Labs Bosanquet 810 Bosanquet
Dualo Du-Touch S Dualo Hexagonal tiling, multiple layouts: dualo (major 3rd × semitone), diatonic dualo, Jankó, chromatic accordion 52 In production €499
Striso board Striso Wicki-Hayden (but the tiling angle is not 60°) 61 In production €480
Exquis Dualo Hexagonal tiling, dualo layout (major 3rd × semitone) 61 Taking preorders, announced for end of summer 2023 €269

Keyless controllers

Product Manufacturer
Continuum Fingerboard Haken Audio
R2M Ribbon Controller Doepfer
LinnStrument Roger Linn Design
SoundPlane A Madrona Labs

Pad controllers

External links

DIY links

Touchscreens in general:

Touchscreen approaches:

Gesture-based controllers:

Apple Magic Trackpad:

Mechanical keyboard switches:



Other MIDI controllers:

Keyboard concepts