Duet concertina

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).