A pentachord in music theory may be either of two things. In pitch-class set theory, a pentachord is defined as any five pitch classes, regarded as an unordered collection ( Roeder 2001). In other contexts, a pentachord may be any consecutive five-note section of a diatonic scale ( Latham 2002). A pentad is a five-note chord ( Bailey 1991, 450).
Under the latter definition, a diatonic scale comprises five non-transpositionally equivalent pentachords rather than seven because the Ionian and Mixolydian pentachords and the Dorian and Aeolian pentachords are intervallically identical (CDEFG=GABCD; DEFGA=ABCDE).
The name "pentachord" was also given to a musical instrument, now in disuse, built to the specifications of Sir Edward Walpole. It was demonstrated by Karl Friedrich Abel at his first public concert in London, on 5 April 1759, when it was described as "newly invented" ( Knape, Charters, and McVeigh 2001). In the dedication to Walpole of his cello sonatas op. 3, the cellist/composer James Cervetto praised the pentachord, declaring: "I know not a more fit Instrument to Accompany the Voice" ( Charters 1973, 1224). Performances on the instrument are documented as late as 1783, after which it seems to have fallen out of use. It appears to have been similar to a five-string violoncello ( McLamore 2004, 84).
References
- Bailey, Kathryn. 1991. The Twelve-note Music of Anton Webern: Old Forms in a New Language. Music in the Twentieth Century 2. Cambridge and New York: Cambridge University Press. ISBN 978-0-521-39088-0 (cloth). Reprinted Cambridge: Cambridge University Press, 2004. ISBN 978-0-521-54796-3 (pbk). Digital paperback reprint, Cambridge and New York: Cambridge University Press, 2006.
- Charters, Murray. 1973. "Abel in London". The Musical Times 114, no. 1570 (December): 1224–26.
- Knape, Walter, Murray R. Charters, and Simon McVeigh. 2001. "Abel: (4) Carl Friedrich Abel". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell. London: Macmillan Publishers.
- Latham, Alison (ed.). 2002. "Pentachord". The Oxford Companion to Music. Oxford and New York: Oxford University Press. ISBN 0-19-866212-2.
- McLamore, Alyson. 2004. "'By the Will and Order of Providence': The Wesley Family Concerts, 1779–1787". Royal Musical Association Research Chronicle, no. 37 (2004): 71–220.
- Roeder, John. 2001. "Set (ii)." The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell. London: Macmillan Publishers.
Further reading
- Rahn, John. 1980. Basic Atonal Theory. Longman Music Series. New York and London: Longman Inc.. ISBN 0-582-28117-2.
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