Editing Harpsichord (section)

==Multiple manuals and choirs of strings==
[[File:Klikli.jpg|thumb|right|200px|A two-manual harpsichord]]

While many harpsichords have one string per note, more elaborate harpsichords can have two or more strings for each note. When there are multiple strings for each note, these additional strings are called "choirs" of strings. This provides two advantages: the ability to vary volume and ability to vary tonal quality. Volume is increased when the mechanism of the instrument is set up by the player (see below) so that the press of a single key plucks more than one string. Tonal quality can be varied in two ways. First, different choirs of strings can be designed to have distinct tonal qualities, usually by having one set of strings plucked closer to the nut, which emphasizes the higher [[harmonic]]s, and produces a "nasal" sound quality. The mechanism of the instrument, called "stops" (following the use of the term in [[pipe organ]]s) permits the player to select one choir or the other. Second, having one key pluck two strings at once changes not just volume but also tonal quality; for instance, when two strings tuned to the same pitch are plucked simultaneously, the note is not just louder but also richer and more complex.

A particularly vivid effect is obtained when the strings plucked simultaneously are an [[octave]] apart. This is normally heard by the ear not as two pitches but as one: the sound of the higher string is blended with that of the lower one, and the ear hears the lower pitch, enriched in tonal quality by the additional strength in the upper harmonics of the note sounded by the higher string.

When describing a harpsichord it is customary to specify its choirs of strings, often called its [[disposition (harpsichord)|disposition]]. To describe the pitch of the choirs of strings, pipe organ terminology is used. Strings at [[eight-foot pitch]] (8') sound at the normal expected pitch, strings at four-foot pitch (4') sound an octave higher. Harpsichords occasionally include a sixteen-foot (16') choir (one octave lower than eight-foot) or a two-foot (2') choir (two octaves higher; quite rare). When there are multiple choirs of strings, the player is often able to control which choirs sound. This is usually done by having a set of jacks for each choir, and a mechanism for "turning off" each set, often by moving the upper register (through which the jacks slide) sideways a short distance, so that their plectra miss the strings. In simpler instruments this is done by manually moving the registers, but as the harpsichord evolved, builders invented levers, knee levers and pedal mechanisms to make it easier to change registration.

Harpsichords with more than one keyboard (this usually means two keyboards, stacked one on top of the other in a step-wise fashion, as with pipe organs) provide flexibility in selecting which strings play, since each manual can be set to control the plucking of a different set of strings. This means that a player can have, for instance, an 8' manual and a 4' manual ready for use, making it possible to switch between them to obtain higher (or lower) pitches or different tone. In addition, such harpsichords often have a mechanism (the "coupler") that couples manuals together, so that a single manual plays both sets of strings.

The most flexible system is the French "shove coupler", in which the lower manual slides forward and backward. In the backward position, "dogs" attached to the upper surface of the lower manual engage the lower surface of the upper manual's keys. Depending on choice of keyboard and coupler position, the player can select any of the sets of jacks labeled in "figure 4" as A, or B and C, or all three.

[[File:Shove Coupler.svg|center|thumb|800px|Figure 4. French shove coupler. To the left: uncoupled keyboards. The depressed upper key lifts the jack A upwards. The depressed lower key lifts jacks B and C. To the right: The upper keyboard is coupled to the lower one by pulling the latter. The depressed upper key lifts the jack A upwards. The depressed lower key lifts jacks A, B and C.]]

The English "dogleg" jack system (also used in Baroque Flanders) does not require a coupler. The jacks labeled A in Figure 5 have a "dogleg" shape that permits either keyboard to play A. If the player wishes to play the upper 8' from the upper manual only and not from the lower manual, a stop handle disengages the jacks labeled A and engages instead an alternative row of jacks called "lute stop" (not shown in the Figure). A lute stop is used to imitate the gentle sound of a plucked [[lute]].<ref>Find full details in {{Harvnb|Hubbard|1967|p=133 ff.}}, {{Harvnb|Russell|1973|p=65 ff.}}, {{Harvnb|Kottick|2003}}.</ref>
[[File:Dogleg shove coupler.svg|center|thumb|400px|Figure 5. Dogleg jack, English coupler system. When depressed, the upper key lifts the "dogleg" jack (jack A) upwards. The lower key lifts all three jacks A, B, and C.]] The use of multiple manuals in a harpsichord was not originally provided for the flexibility in choosing which strings would sound, but rather for [[transposition (music)|transposition]] of the instrument to play in different keys (see ''[[History of the harpsichord]]'').
[[File:ShortOctaveOnC.svg|thumb|right|200px|Some early harpsichords and organs had a [[short octave]] in the lowest register. It replaced rarely used bass notes with more widely used notes.]]

Some early harpsichords used a [[short octave]] for the lowest register.{{citation needed|date=March 2025}} The rationale behind this system was that the low notes F{{Music|#}} and G{{Music|#}} are seldom needed in [[early music]]. Deep bass notes typically form the [[inversion (music)|root]] of the chord, and F{{Music|#}} and G{{Music|#}} chords were seldom used at this time. In contrast, low C and D, both roots of very common chords, are sorely missed if a harpsichord with lowest key E is tuned to match the keyboard layout. When scholars specify the pitch range of instruments with this kind of short octave, they write "C/E", meaning that the lowest note is a C, played on a key that normally would sound E.  In another [[Short octave#Second type|arrangement]], known as "G/B', the apparent lowest key B is tuned to G, and apparent C-sharp and D-sharp are tuned to A and B respectively.