The clavichord is one of the oldest forms of the keyboard. Clavichords first began appearing in manuscripts during the 14th and 15th centuries, as well as in illuminated manuscripts, sculptures and stained glass windows. The clavichord is generally constructed in a rectangular box, with the keyboard projecting on one of the longer sides. The strings run transversely from an anchorage point at the left-hand end, with the tuning pegs on the right-hand side of the instrument. There are two forms of clavichords: fretted, and unfretted. Fretted clavichords are older, and offer two, three, or sometimes even four different notes from one pair of unison strings (they have frets similar to a guitar that run along the strings). Fretted clavichords were common during the 16th and 17th centuries. Unfretted clavichords have a different pair of strings for each individual note (like a modern piano with one key for each note). These instruments began appearing at the end of the 17th century. Instead of hammers, clavichords have a small upright metal blade called a tangent. When a key is depressed, the tangent strikes the string, and remains in contact with the string until the key is let go of. One string of each note is left to vibrate, whilst the other is muted with a strip of felt. Once a note is played, any increase of pressure on the key stretches the string. This can alter the pitch of the note, and allows the player to create an effect similar to vibrato. The clavichord is very gentle in tone. Because of its mechanism, the clavichord is capable of great dynamic range, and much tonal nuance.
Harpsichord is a name used to describe keyboard instruments where the string is plucked to create sound. The strings of the harpsichord are arranged in a parallel manner, running in the same direction as the keys, running from the front of the instrument to the back. Harpsichords can have one, two, and sometimes even three keyboards, which are called manuals. Single manual harpsichords usually have two sets of strings per note, whilst double manual harpsichords usually have a third set of strings that sounds one octave higher than played.
Harpsichord action has remained largely unchanged throughout history. Instead of hammers like on a modern piano, there are vertical wooden shafts (called ‘jacks’) that hold a piece of bird’s quill (plectrum) that plucks the string. Cloth dampers silence the vibrating strings once they have been plucked, and the key returns to resting position. Because the force at which the strings are plucked cannot change (regardless of the force a player uses), the dynamic range of the harpsichord is fixed. Dynamics are instead changed by mechanical means, such as tempi changes in playing, and use of the double manual (use of an extra register).
There are various schools of Harpsichord manufacturing, including the Italian School, the Flemish School, the English School, the French School, and the German School. Italian harpsichords typically have a single manual. The strings are kept with a low tension, and there is a marked attack on the strings. They are described as clear and ‘vocal’ sounding instruments. The Flemish harpsichord was made famous by the Ruckers Family harpsichord makers, which are seen to be the finest and most colourful sounding instruments. Ruckers instruments generally had a double manual, with the upper manual functioning as a transposing keyboard. This keyboard would sound one octave higher than the original manual, and thus sounded like a second instrument playing along with the original harpsichord. English and French harpsichords generally also had a double manual. However, this second manual was used for expression, rather than transposing as on the Ruckers’ instruments. French instruments were also light and airy in tone, where English instruments were heavier and richer in sound. German harpsichords were a blend of all the aforementioned schools, and there was no uniform structure in the build. Germanic instruments tended to sound very unusual, and would sometimes characterise particular instruments from other schools, rather than holding their own unique tone.
The square piano is usually constructed as a rectangular box, with the keyboard set in the longer side of the instrument. Like the clavichord, the strings run from left to right, across the instrument. During the 18th and 19th centuries, the greatest diversity of design and construction occurred on the square piano, with much creativity in design emerging. The square piano was the preferred keyboard instrument during this period, because of its size and shape, and also the greater variety of tone and colour from the instrument.
The term ‘grand’ is used to describe the wing-shape of the body of the instrument. Like the harpsichord, the strings are arranged in the same direction as the keys, but with the bass strings running diagonally to converge over the centre of the soundboard. These instruments were (and still are) used mainly for performances and concert, rather than being domestic instruments.
The term ‘upright’ is used to describe the shape and positioning of the strings within the body of the instrument. Instead of the strings and soundboard running horizontally through the instrument (like in a grand or square instrument), upright pianos have vertically running strings and soundboards. The action is positioned in the middle of the strings (instead of at the head), approximately at eye-level of the performer. Upright pianos first started to appear in the 19th century, and were not popular until the 20th century, when square pianos became less and less common. They were then seen as a cheaper option to grand pianos, and also became the favoured domestic keyboard instrument as they took up less space.