Harpsichord - Multiple Choirs of Strings

Multiple Choirs of Strings

Many harpsichords have exactly one string per note. There are several reasons why it is sometimes an advantage to have more. When there are two choirs of strings at the same length, it is possible to arrange for them to give different tonal qualities, and thus to increase the variety of sound produced by the instrument. This is done by having one set of strings plucked closer to the nut, which emphasizes the higher harmonics, and produces a "nasal" sound quality. When two strings tuned to be the same pitch, or to an octave apart, are plucked simultaneously by a single keystroke, the note is louder and richer than one produced by a single string. The qualitative distinction is particularly noticeable when the strings are tuned an octave apart.

When describing a harpsichord it is customary to specify its choirs of strings, often called its disposition. Strings at eight foot pitch sound at the normal expected pitch, strings at four foot pitch sound an octave higher, and sometimes harpsichords have the rare 16-foot pitch (one octave lower than eight-foot) or two-foot pitch (two octaves higher).

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.

More flexibility in selecting which strings play is available in harpsichords having more than one keyboard or manual, since each manual can control the plucking of a different set of strings. In addition, such harpsichords often have a mechanism to couple manuals together, so that two can be used while actually playing on only one. The most flexible system is the French shove coupler, in which the lower manual can slide forward and backward, so that 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.

The English dogleg jack system (also practised in Baroque Flanders) does not require a coupler. The jacks labeled A in Figure 5 have a "dogleg" shape that permits A to be played by either keyboard. 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). Find full details in Hubbard 1967, p.133 ff., Russell 1973, p.65 ff. and Kottick 2003.

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; for discussion see History of the harpsichord.