A full size accordion usually has 120 bass buttons. They all look the same, most of them feel the same, some of them even sound the same, so what do all these left hand accordion buttons do?
The first two rows on a 120 bass accordion play bass notes which are usually low sounding. The second of these bass rows is called the fundamental bass row. On some smaller accordions, this may be the only row of bass notes present. It is arranged in the same order as the “circle of fifths”. As you move up the accordion’s left hand keyboard, each note is a perfect 5th higher than the previous one.
The first row of bass buttons (sometimes not present on some smaller accordions) on the accordion is called the counterbass row. Each button in this counterbass row is a major 3rd higher than the adjacent button in the fundamental row. Having this extra row of counterbass buttons can make it easier to play certain notes without having to stretch for them or jump around the keyboard quite so much.
The chord rows aren’t always available on some smaller accordions. It is usually the diminished chord row that is left out as for example on a 60 bass accordion or an 80 bass accordion. Traditionally, diminished chords haven’t been very often needed – perhaps apart from in more advanced classical music. It is however becoming more common for players of traditional music, jazz and tango for example to use the diminished chords in combination with other chords to make more complex chords to create more interesting harmonies.
The first row of chords on the accordion is one row further out from the bellows than the fundamental bass row. Buttons in this row play major chords with the same name as the adjacent button in the fundamental row. For example, the major chord button next to the C fundamental bass button will play a C major chord.
The second row of chords on the accordion is one row further out from the bellows than the major chord row. Buttons in this row play minor chords with the same name as the adjacent button in the major chord row next to it. For example, the minor chord button next to the C major chord button will play a C minor chord.
We would suggest that if you are choosing your first accordion, even if you expect to upgrade at some point in the future, choose one that has major AND minor chords as a minimum.
The next row of buttons out from the bellows plays dominant seventh chords so the button next to a C minor chord is a C seventh chord. The final row of buttons furthest away from the bellows on the accordion plays diminished seventh chords.