Accordion · 6 min read

Accordion registers, explained

Bassoon, clarinet, master, musette: what each register switch does to the reeds, what the dot diagrams mean, and how to choose one that suits the music.

2026-06-18

What a register actually is

Inside an accordion the reeds are grouped into ranks. A rank is a complete set of reeds covering the keyboard at one pitch level. A typical four-rank treble instrument carries one rank an octave below written pitch, two ranks at written pitch, and one an octave above.

Behind each rank sits a slider, a perforated strip of wood or metal that can cover or uncover the openings into that rank's chambers. A register switch moves those sliders. Press a switch and you are not changing the notes, the fingering or the volume in any fundamental way. You are choosing which ranks of reeds the air is allowed to reach.

This is borrowed directly from the pipe organ, and so is the vocabulary. Sixteen-foot means an octave below written pitch, eight-foot means written pitch, four-foot means an octave above. The numbers refer to the length organ pipes would need to be, which is meaningless for reeds but the naming stuck.

Reading the dot diagrams

Register switches are usually labelled with a small circle divided into three horizontal bands, with dots in them. The top band is the four-foot rank, the middle band the eight-foot ranks, the bottom band the sixteen-foot. A dot means that rank is sounding.

So a single dot in the middle is one eight-foot rank alone: the clean tone usually called clarinet. A single dot at the bottom is sixteen-foot alone, called bassoon, the dark low register. Two dots side by side in the middle band means both eight-foot ranks, the wet or musette sound. Dots in all three bands is the full sound, called master, and on many instruments it is the least useful setting despite being the loudest.

Once you can read the diagrams you can read any accordion's switches without knowing the maker's naming conventions, which vary and are not standardised.

The common registers and what they are for

Bassoon, sixteen-foot alone, is warm and rounded and sits below the singer or the melody instrument. It is the register for accompaniment, for bass lines, and for anything that should not compete with a voice.

Clarinet, a single eight-foot rank, is the plainest and most honest sound the instrument has. It is what you want for counterpoint, for Bach, for anything where inner voices need to stay separate. Beginners tend to avoid it because it sounds thin on its own, then discover after a few years that it is the register they use most.

Musette combines two or three eight-foot ranks tuned deliberately apart. The beating between them produces the shimmer everyone associates with a Paris street corner. French instruments often use three ranks with the outer two tuned sharp and flat of the middle. It is glorious in its place and a disaster in polyphony, where every beat blurs the voices together.

Piccolo, four-foot alone, is bright and cutting and useful for a brief change of colour or for doubling a melody an octave up. Very little music wants it for long.

Cassotto, chin switches and the left hand

On better instruments some ranks speak into a cassotto, a tone chamber built into the body that softens and darkens them before the sound reaches the grille. On a typical cassotto instrument the sixteen-foot and one eight-foot rank are in the chamber and the others are outside it, which means two eight-foot ranks can be nominally identical in pitch but quite different in colour. This is why one switch on a concert instrument can sound noticeably rounder than another that the diagram says is the same.

Many instruments also have chin switches along the top of the treble side, operated with the jaw so you can change register without taking a hand off the keyboard. They feel absurd for about a week and then become indispensable.

The left hand has its own registers too, usually fewer, typically switching between a full bass sound and a thinner one for lighter accompaniment. They are worth exploring; most players find their bass switches by accident years after buying the instrument.

Choosing one, and when to change

The practical rule is to pick a register for the musical function, not the volume. Ask what the passage is doing. Carrying a melody over an ensemble? Something with four-foot in it. Supporting a singer? Bassoon or a single eight-foot. Playing three independent voices? A single rank, almost always.

Mark register changes in your score, and practise the change itself, because a switch pressed mid-phrase makes an audible click and a momentary gap if you are clumsy about it. Good players change registers at phrase joins and rests, and you stop noticing that they did it. Our free score library at A&G Academy carries suggested registrations in a fair number of the arrangements, which is a reasonable place to start before you form your own opinions.

Frequently asked

What do the buttons above the accordion keyboard do?

Those are register switches. They slide covers over the reed chambers inside, switching whole ranks of reeds in and out of play. They change the tone colour, not the pitch of the notes you finger. Names like bassoon, clarinet, musette and master describe which combination of low, middle and high ranks is sounding.

What does musette tuning mean on an accordion?

Musette means two or three reed ranks at the same nominal pitch are deliberately tuned slightly apart. The small difference makes the notes beat against each other, producing the wavering shimmer of French and Italian popular accordion. The wider the detuning, the stronger the effect. Bayans and concert instruments are tuned dry, without it.

Which accordion register should I use for classical music?

Usually a single eight-foot rank, the register often labelled clarinet, because detuned musette ranks blur independent voices together. For darker colours, a single sixteen-foot rank works well. On a cassotto instrument, the eight-foot rank inside the tone chamber is generally the best choice for counterpoint.


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