Diapason
From Wikipedia, the free encyclopedia
The word diapason (pronounced [ˌdaɪəˈpeɪsən]) is another name for the musical interval of the octave, especially in the context of Pythagorean intervals. In other contexts, it can mean the range of a musical instrument or voice. It also has more specific uses:
Contents |
[edit] Organ stop
The diapason is the principal, or foundation, stop of the pipe organ, which has pipes throughout the entire range of the instrument. Diapason pipes give the organ its characteristic sound, and the 8-foot diapason (that is, the one which sounds middle C when middle C is pressed) may be said to be the one stop that is essential on virtually all organs of all sizes.
Diapasons come in two varieties: open, where the end of the pipe is clear, producing a bright sound; and stopped where the end of the pipe is blocked, producing a more muffled, sweeter sound. The name diapason is also used on some electronic organs for voices which imitate the pipe organ stop.
A stop of diapason tone quality is not always called diapason. "Diapason" is most commonly used in English-style organs, whereas the same type of stop is known as a "Prinzipal" or "Principal" on German-style organs and a "Montre" or "Praestant" on French-style organs. Also, stops of this tone quality at higher pitches often go by other names: for example, on English-style organs, the stops called Principal and Fifteenth sound one octave and two octaves respectively above the 8-foot Diapason; or on German-style organs, the name Octav is used to indicate the stop an octave above the 8-foot Prinzipal.
The "Tibia Clausa", which is designed much more like the organ stop known as a bourdon is the fundamental tone of the theatre organ rather than the diapason.
[edit] Pitch standard
Diapason is also used to refer to a physical implementation of a pitch standard, for instance a tuning fork used as a standard.
[edit] The diapason normal
Diapason Normal is the name given to the historical pitch standard where the A above middle C is tuned to 435 Hz. This standard was set by law in 1859 in France, and became popular throughout Europe. In 1939, A = 440 Hz was codified as the international standard of concert pitch for broadcast music, and has replaced the diapason normal.
