The Duet concertina is a family of concertinas, distinguished by being unisonoric (producing the same note on the push and pull of the bellows, unlike the Anglo concertina) and by having their lower notes on the left and higher on the right (unlike the English concertina).
Instruments built according to various duet systems are the last development step in the history of the instrument and less common than other concertinas. Duet concertina systems aim to simplify playing a melody with an accompaniment. To this end the various duet systems feature single note button layouts that provide the lower (bass) notes in the left hand and the higher (treble) notes in the right, usually with some overlap (like a two-manual organ).
One of the first recorded concertina players was Alexander Prince, who as early as 1906 was recorded playing his Maccann-system Duet concertina on the Zonophone label. Fellow vaudevilleiean Percy Honri also specialized in the Maccann system.
Despite the predominance of the Anglo concertina, the instrument found a small level of adoption in the Boeremusiek of the Afrikaner people of South Africa, who refer to the Crane and Maccann duet systems as the 5-ry ("five row") and 6-ry ("six row"), respectively.
The most common key layouts within the Duet system are:
- Maccann system (or McCann), the most widely produced vintage Duet system, an improvement on Wheatstone's earlier Duette system, patented by "Professor" John Hill Maccann in 1884 and licensed to Lachenal & Co.
- Crane system, patented in 1896, and adopted by the Salvation Army in 1912 and labeled the "Triumph" system. It is said to be "easier to learn than the McCann or Jeffries".
- Jeffries system, less common than the above, and though unisonoric the layout of the buttons resembles that of the Anglo concertina. The distribution of notes is described as "splendidly haphazard".
- Hayden system, invented in 1963 and patented in 1986, is an isomorphic system in which all scales and intervals are arranged uniformly. Years after its invention, it was discovered that a nearly identical layout by Swiss designer Kaspar Wicki had been patented in 1896. Though a more recent development, the majority of newly-produced Duet concertinas since the 1980s are in the Hayden system.
There are a number of other types, far less common: a 1983 article notes patents including "Sharp's 1890, Hank's 1896, Huish's 1901 , and a number of Patents by Dr. Pitt-Taylor between 1916 and 1924." Duet concertina designer Brian Hayden has also noted the Linton, Chidley, and Piano systems, the last including variants such as the Rust system and Jedcertina.
Duet concertinas are held by placing the hands through a leather strap, with thumbs outside the strap and palms resting on wooden bars. The largest duets play bass notes down to C below the stave, and a competent performer can play solo piano music with little compromise.
- Giacomo Meyerbeer (1 January 2002). The Diaries of Giacomo Meyerbeer: The years of celebrity, 1850-1856. Fairleigh Dickinson Univ Press. pp. 138–. ISBN 978-0-8386-3844-6.
- Frank Hoffmann (12 November 2004). Encyclopedia of Recorded Sound. Routledge. pp. 1695–. ISBN 978-1-135-94950-1.
- John Shepherd (8 July 2003). Continuum Encyclopedia of Popular Music of the World: VolumeII: Performance and Production. A&C Black. pp. 298–. ISBN 978-0-8264-6322-7.
- "Musical Instruments: Concertina". Boermusiek.org. Retrieved 17 November 2014.
- Dan Michael Worrall (1 January 2009). The Anglo-German Concertina: A Social History. Dan Michael Worrall. pp. 30–. ISBN 978-0-9825996-1-7.
- English Dance and Song. English Folk Dance and Song Society. 1983. p. xlix.
- Susan Cohen (17 September 2013). The Salvation Army. Osprey Publishing. pp. 49–. ISBN 978-0-7478-1422-1.
- Canada Folk Bulletin. Vancouver Folk Song Society. 1978. p. 47.
- EDS. English Folk Dance and Song Society. 1967. p. 104.
- English Dance and Song. English Folk Dance and Song Society. 1983. p. 74.
- Maria Dunkel (1987). Bandonion und Konzertina. E. Katzbichler. p. 92.
- English Dance & Song. English Folk Dance and Song Society. 1983. p. 1983.
- Williams, Wes (15 February 2003). "A Chat with Brian Hayden". Concertina.com. Retrieved 20 June 2015.