This is a "broad stroke" explanation of concertinas, the different keyboard layouts, reed types, and quality classifications. Its purpose is primarily to provide an elementary understanding of the differences between the available models.

Concertinas are available in 3 keyboard layouts

Anglo

• each button plays a different note on 'pull' and 'push', much like a (mouth) harmonica.

• keyboard: consists of 2 (20 button) or 3 (30 button) rows of buttons per side of which row 1 is in the dominant key, and row 2 in the tonic key. Row 3 consists of notes not included in the 1st and 2nd row as well as a few doubles. Row 1 and 2 are in major keys: C/G, G/D, Bb/F etc. Anglos are available in  Wheatstone/Lachenal and Jeffries.
  The majority of the anglos are Wheatstone/lachenal.

• pros: great for tonal and some modal (e.g. pentatonic) music. Initially easy to play simple tonal tunes because of the lay out of the keyboard.

• cons: partially chromatic, not possible/very difficult to play outside the primary keys or non tonal music.

• use: primarily in traditional music. (e.g. Irish, English, etc.)  

• models: Concertina Connection models: Rochelle, Rochelle-2 (R2), Minstrel, Clover,
                Wakker models: A1, A2, A3. A4, A5 and A6

English

• each button plays the same note on 'pull' and 'push', like an accordion.

• keyboard consists of 4 rows per side of which the middle 2 rows are the 'white' keys, and the outer rows the 'black keys' of the piano. 

• pros: fully chromatic, allows playing in all keys. The english is the 'original' concertina, and has a considerable classical (19-20th century) repertoire.

• cons:  relative easy to learn single line melodies, steep learning curve for original repertoire, which includes polyphonic/chordal music.

• use: original classical repertoire, folk, ethnic (also non European), jazz, etc..  

• models: Concertina Connection models: Jackie, Jack, Busker, Rose,
                Wakker models: E1, E2, E3, E4 and Parnassus

Duet

• each button plays the same note on 'pull' and 'push', like the english.

• keyboard: there are several keyboard layouts in use.  We build primarily Wicky, Hayden and McCann duets.
  The low notes are always on the left side (accompaniment, bass clef), and the treble notes on the right side (melody, treble clef), much like a piano.

• pros: small duets partly, large duets are fully chromatic, allows playing in most/all keys.  

• cons: relative easy to learn single line melodies, steeper learning curve for polyphonic/chordal music.

• use:  folk, jazz, some classical, etc..   

• models: Concertina Connection models: Elise, Troubadour, Peacock,
                Wakker models: H1, H2, W1 and W2, C2

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