The National Music Museum in Vermillion, SD features a diatonic button accordion by Berlin maker J. Pomm, with up to three treble rows balanced by eight bass buttons.
Diatonic accordions produce notes when closing and opening their bellows, though they are limited to playing one key and cannot produce chromatic scales like those produced by chromatic bandoneons.
Keys
Diatonic button accordions (or melodeons) feature a melody-side keyboard with one or more rows that create diatonic scale notes – meaning no sharps or flats; just natural notes in C or G (or sometimes B).
Contrasting with chromatic accordions which contain both flats and sharps to allow you to play all musical keys simultaneously. The bass side of an accordion may either be diatonic or chromatic depending on how it’s tuned.
My accordions are set up as diatonic octaves – meaning the outer row of buttons produces chords with my right hand while my inner row produces basses (in C). This allows me to play alongside musicians who may be playing different keys, and makes reading sheet music written in standard staff notation much simpler for me.
Reeds
If your accordion is left exposed to direct sunlight for extended periods, its cellulose will eventually discolour over time and disintegrate over time. You may still use your instrument, but will need to buy replacement reeds (usually two separate sets) quickly in order to play effectively again.
Sand down the reed plates and carve out new holes for the reed tongues if necessary; this requires special tools. However, beginners should steer clear from this undertaking.
Diatonic accordions feature a limited bandoneon keyboard on the melody side and just a few rows of buttons on the bass side, and are used across numerous musical genres and modern instruments that incorporate traditional elements. A diatonic button accordion is usually bisonoric – meaning each reed plays a different note depending on whether you push or pull on its bellows – though some unisonoric models also exist that play all notes regardless of bellows direction. Englishers refer to these instruments as melodeons; in France it’s known as accordeon diatonic; Basque Country people refer to these instruments as trikitixa or soinu txikia; in Switzerland it’s called Schwyzerorgeli.
Bass
Diatonic accordions feature buttons that produce different notes based on whether the bellows are being compressed or stretched, creating differences in air pressure that vibrate the reeds to produce sounds. A right hand keyboard contains keys which represent tones from specific diatonic scales while its left-hand counterpart may play chords based on major or minor triads.
Diatonic button accordions, also referred to as melodeons, feature several rows of keys on the right side (melody) and two or three on the left (basses). Melody keys correspond to notes within one diatonic scale while bass buttons sound chord root notes in pairs.
Some accordions feature additional sets of reeds called couplers to expand chordal range, making these instruments exceptionally flexible instruments with up to five registers in the bass register alone!
Keyboard layout
Diatonic accordions feature a uniform button layout and limited range of notes, often tuned a fourth apart (which does not include all sharps or flats) and more closely resembling chromatic accordions than piano accordions.
A one row diatonic melodeon is a popular instrument in Irish/Celtic music as well as Norteno, Conjunto and Zydeco styles. This instrument typically features ten buttons on its melody side with two bass buttons providing twenty total notes; usually organized into a pattern of major, minor and diminished chords.
These other single-action button accordions, known as bisonorics, feature an unusual arrangement of keys that produce two notes when the bellows is pushed or pulled, just like harmonicas. Beginners will find these accordions easy to finger quickly thanks to close together buttons making fumbling less of an issue; however this type is generally not used for playing songs due to lack of range to produce full scale melodies.