A split sharp is a kind of

key Key or The Key may refer to: Common meanings * Key (cryptography), a piece of information that controls the operation of a cryptography algorithm * Key (lock), device used to control access to places or facilities restricted by a lock * Key (ma ...

found in some early

keyboard instrument A keyboard instrument is a musical instrument played using a keyboard, a row of levers which are pressed by the fingers. The most common of these are the piano, organ, and various electronic keyboards, including synthesizers and digital pianos ...

s, such as the

harpsichord A harpsichord ( it, clavicembalo; french: clavecin; german: Cembalo; es, clavecín; pt, cravo; nl, klavecimbel; pl, klawesyn) is a musical instrument played by means of a musical keyboard, keyboard. This activates a row of levers that turn a ...

clavichord The clavichord is a stringed rectangular keyboard instrument that was used largely in the Late Middle Ages, through the Renaissance, Baroque and Classical eras. Historically, it was mostly used as a practice instrument and as an aid to composit ...

, or organ. It is a musical key divided in two, with separately depressible front and back sections, each sounding its own pitch. The particular keys that were split were those that play the sharps and flats on the standard

musical keyboard A musical keyboard is the set of adjacent depressible levers or keys on a musical instrument. Keyboards typically contain keys for playing the twelve notes of the Western musical scale, with a combination of larger, longer keys and smaller, s ...

(the " black keys" on a modern piano). Split sharps served two distinct purposes. First, in the

broken octave The short octave was a method of assigning notes to keys in early keyboard instruments (harpsichord, clavichord, organ), for the purpose of giving the instrument an extended range in the bass range. The rationale behind this system was that the l ...

, they allowed an instrument to include deep

bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Music * Bass (sound), describing low-frequency sound or one of several instruments in the bass range: ** Bass (instrument), including: ** Acoustic bass gu ...

notes while retaining a short, compact keyboard. Second, in older music, tuning was generally not done by

equal temperament An equal temperament is a musical temperament or tuning system, which approximates just intervals by dividing an octave (or other interval) into equal steps. This means the ratio of the frequencies of any adjacent pair of notes is the same, ...

, which treats note pairs such as A and B as the same pitch. Instead, they were assigned slightly different pitches on

enharmonic keyboard An enharmonic keyboard is a musical keyboard, where enharmonically equivalent notes do not have identical pitches. A conventional keyboard has, for instance, only one key and pitch for C and D , but an enharmonic keyboard would have two differen ...

s (particularly in "

meantone temperament Meantone temperament is a musical temperament, that is a tuning system, obtained by narrowing the fifths so that their ratio is slightly less than 3:2 (making them ''narrower'' than a perfect fifth), in order to push the thirds closer to pure. Me ...

"). This allowed certain musical intervals, such as the

major third In classical music, a third is a musical interval encompassing three staff positions (see Interval number for more details), and the major third () is a third spanning four semitones. Forte, Allen (1979). ''Tonal Harmony in Concept and P ...

, to sound closer to their ideal

just Just or JUST may refer to: __NOTOC__ People * Just (surname) * Just (given name) Arts and entertainment * ''Just'', a 1998 album by Dave Lindholm * "Just" (song), a song by Radiohead * "Just", a song from the album ''Lost and Found'' by Mudvayne ...

value, hence more closely tuned to

just intonation In music, just intonation or pure intonation is the tuning of musical intervals as whole number ratios (such as 3:2 or 4:3) of frequencies. An interval tuned in this way is said to be pure, and is called a just interval. Just intervals (and ...

. Split sharps present advantages and disadvantages: "Obviously this would have its advantages under some circumstances in terms of intonation. However, the complexities of fingering and hand position dictated by such a keyboard configuration presented problems." Specifically: "Such devices were obviously an impediment to rapid scale work in the lowest bass register, but this does not matter greatly as Italian seventeenth-century music generally avoids writing of this kind." In modern usage, split sharps are usually the method of choice for custom keyboards that play

19 equal temperament In music, 19 Tone Equal Temperament, called 19 TET, 19 EDO ("Equal Division of the Octave"), or 19 ET, is the tempered scale derived by dividing the octave into 19 equal steps (equal frequency ratios). Each step represent ...

, which, like meantone, uses different pitches for sharps and flats that are enharmonic in the standard 12 tone.See
www.n-ism.org
"Historically, 19-tone keyboards have been constructed...with the rear of the divided black keys often raised."

Notes

References

Further reading