In the construction of the Harpsichord each string is wound around a tuning pin. When rotated with a wrench or tuning hammer, the tuning pin adjusts the tautness so to make the instrument sound the correct pitch. Tuning pins are confined tightly in holes bored in the pinblock or wrestplank, an oblong hardwood board.

The case holds in position the pinblock, soundboard, hitchpins, keyboard, and the jack action. It normally includes a solid underside, and also built-in bracing to keep it from warping under the tension of the strings. Cases vary, the Italian harpsichords are frequently of light construction; where the Flemish instruments and those derived from them, have a heavier construction.

Starting at the tuning pin, a string next runs over the nut, a sharp edge piece of hardwood and is connected to the wrestplank. The part of the string beyond the nut is what creates its vibrating duration.

At the opposite end of its vibrating length, the string passes over the bridge, which is made very much like the pinblock. As with the nut, a vertical pin entered into the bridge establishes the placement of the string along the bridge.

The bridge itself rests on a soundboard a fine panel of wood normally made of spruce or (in Italian harpsichords) cedar. The soundboard sends the vibrations into the air; without a soundboard, there would be no amplification.

The string is attached at its end by a loop to a hitchpin, which secures it to the case.

Many harpsichords have exactly one string per note. When there are strings at the same distance, they can be given different tonal timbers, which gains a diversity of sound. Having one set of strings plucked closer to the nut, creates higher harmonics and makes a "nasal" sound timbre. When two strings tuned to be the identical pitch, or to an octave apart, are plucked at the same time by a single keystroke, the note is louder and richer than a single string. Strings at eight-foot sound at the regular pitch, strings at four-foot pitch sound an octave higher, and sometimes, even though rare, some have a 16-foot pitch or two-foot pitch creating higher octaves.

When there are multiple strings, the player is often able to control which choirs sound. This is usually done by having a set of jacks for every choir, and a way to "turn off" each set, often by moving the upper-level register (through which the jacks slide) sideways a short length, so that their picks escape the strings. In more simple instruments this is done by manually moving the registers. Later, builders invented levers, knee levers and pedal mechanisms to make it easier to change. In addition, some harpsichords have a mechanism to pair manuals together, so that two can be used while actually playing one. The easiest is the French shove coupler, in which the lower manual can slide forward and backward. Depending on choice of keyboard and coupler position, the player can select any of the positions of jacks.