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 (map ...

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 piano ...

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 keyboard. This activates a row of levers that turn a trigger mechanism ...

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 compositi ...

, or

organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic keyboard instrument ** Hammond ...

. 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, sho ...

(the "

black keys Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ha ...

" on a modern piano). Split sharps served two distinct purposes. First, in the broken octave, they allowed an instrument to include deep bass notes while retaining a short, compact keyboard. Second, in older music,

tuning Tuning can refer to: Common uses * Tuning, the process of tuning a tuned amplifier or other electronic component * Musical tuning, musical systems of tuning, and the act of tuning an instrument or voice ** Guitar tunings ** Piano tuning, adjusti ...

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, wh ...

, 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 different ...

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 Interval may refer to: Mathematics and physics * Interval (mathematics), a range of numbers ** Partially ordered set#Intervals, its generalization from numbers to ...

. 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