Guide

Types of button accordion, and what a melodeon is

By SGWNI, 25 October 2026

Button accordions come in a confusing number of kinds, and the names change from country to country. Three questions sort nearly all of them: does a button play the same note both ways, how far apart are the rows, and what's on the bass side?

What a melodeon is

In Britain a melodeon is a diatonic button accordion: each row of buttons is a major scale, and each button plays one note on the push and another on the pull. One-, two- and three-row boxes can all be called melodeons. In Ireland the word usually means only the one-row box, and two-row boxes such as the B/C are button accordions, or just the box.

In 19th-century America a melodeon was something else entirely: a small reed organ played from a keyboard, made by firms such as Mason & Hamlin. The melodion was another instrument again, a keyboard instrument made by Johann Christian Dietz in the early 1800s; for the accordion, it's just a different spelling.

Push and pull, or the same both ways

A box that plays a different note on the push and the pull is bisonoric. Melodeons, B/C and C♯/D boxes and the three-row boxes of Tex-Mex music are all bisonoric. A box that plays the same note both ways is unisonoric, like the piano accordion and the chromatic button accordion.

This was there from the start. The name accordion comes from a Vienna patent of May 1829, by Cyrill Demian, for an instrument that already gave a different chord on the push and the pull.

One-row boxes

The simplest box has ten buttons in one row and two on the bass side, a bass note and a chord. On the push you get the home key and on the pull the chord a fifth above, so a tune stays in one key. The Cajun accordion is a one-row, most often in C, and Cajun players play largely on the pull.

Two rows a fourth apart: D/G and G/C

The usual English melodeon has 21 treble buttons, eleven on the outside row and ten inside, and eight basses. The two rows are a fourth apart, each a major scale, and the box is named after them with the outside row first: a D/G has a D row outside and a G row inside.

D/G is the common box for English folk and morris music. G/C is more common in France and the rest of continental Europe. Button for button, a G/C is a fifth lower, though continental players use its upper notes a lot, so the music doesn't always sound lower. Other pairs exist, such as C/F and A/D. The D/G or G/C guide compares the two, and the D/G and G/C charts list every button.

Two rows a semitone apart: B/C and C♯/D

The Irish button accordion has its two rows a semitone apart. B/C is the most widely played system in Irish music, and C♯/D is gaining ground. With the rows so close, between them they hold nearly every note, so a B/C can play in any key, but each key needs its own fingering. They have 21 or 23 treble buttons and eight basses. The B/C guide explains how it works, and the B/C chart has every button.

Two and a half rows

Some boxes add a short third row to a two-row. It holds extra accidentals and reversals, notes the main rows only give in the other bellows direction. There's no standard for what goes on it. Most of these boxes have twelve basses, which makes them heavier.

Three rows: GCF, FB♭E♭ and EAD

Three-row boxes with each row a fourth from the next are used for Tex-Mex, norteño and Colombian vallenato. The Hohner Corona III, for example, has 31 treble buttons in three rows and twelve basses, in A/D/G, G/C/F or B♭/E♭/A♭. Other three-row tunings include F/B♭/E♭ and E/A/D. Three-row boxes are also common in continental Europe in G/C/F.

Alpine boxes

The Steirische Harmonika of Austria, Bavaria and Slovenia is also push and pull, with three to five treble rows, each in its own key, and large bass reeds. Its music is often written in its own notation, Griffschrift, rather than on the staff.

Chromatic button accordions

A chromatic button accordion has three to five rows of buttons that between them give every note, the same on the push and the pull. That means any key can be played with the same fingering. There are two main layouts, B-system and C-system; the B-system is the layout of the Russian bayan. The bass side is the Stradella system, as on a piano accordion, or free bass.

One box breaks the pattern. The British Chromatic, the box Jimmy Shand played, has three push and pull rows in B, C and C♯, which together give every note, with a piano accordion's bass.

Concertinas

Concertinas are related but different: their buttons are on the ends, pressed in line with the bellows, rather than on the side of the keyboard. The Anglo concertina is push and pull; the English concertina is the same both ways.

Which one?

A diatonic box plays most easily in the keys it's tuned to, so the music you want to play, and the people you'll play it with, mostly decide. A D/G suits English session and morris tunes in D and G, and E and B minor. A G/C suits French and Breton music. A B/C or C♯/D suits Irish music. A one-row C suits Cajun music, and a three-row GCF, FB♭E♭ or EAD suits norteño and Tex-Mex. The bass side matters too, and the bass buttons guide covers it.