A reed bank inside an accordion is a full set of the reeds that are used to make different timbres. These reed banks are located in the reed chamber. Most accordions usually have two to four reed blocks in the treble and four or five in the left.
They can be used by themselves or in different combinations to make different sounds by allowing or shutting off the flow of air to certain banks. These combinations are sometimes classified by the instruments they imitate, for instance the clarinet, oboe, and bassoon stops.
The reed banks can be changed by pressing buttons usually found on the side of the accordion. A full-sized instrument usually will also have a "master" or "palm bar" on the right side of the instrument that can be depressed with the palm to turn on all the reed blocks for the fullest accordion sound.
Large instruments might also rarely have chin switches, which are positioned on top of the instrument and can be changed with the performer's chin. This is useful for if you want to change the timbre without having to take your hand off the keyboard.
In a full-sized, four-reed-bank accordion, you will usually have these reeds:
- Two eight-foot (8') or clarinet reeds, or reeds that sound at pitch. They are sometimes tuned differently from each other to create a European, French-style sound (sometimes called musette or wet tuning in accordion parlance). Sometimes they are tuned at the same pitch for a sound more appropriate for classical music (called dry tuning).
- A sixteen-foot (16') or bassoon reed, which sounds an octave below the eight-foot reeds.
- A four-foot (4') or piccolo reed, which sounds an octave above the eight-foot reeds.
Smaller, three-reed accordions are usually missing either the piccolo reed or one of the clarinet reeds.
Sometimes, instead of a four-foot reed there will be a third eight-foot reed that is tuned differently from the other two clarinet reeds. This creates an even more out-of-tune, French-styled sound, but gives you fewer sound possibilities.
On an average instrument, you can use almost any combination of the reeds to produce different sounds suitable for what you're playing.
Following is a table of all eleven possible combinations on a four-voice accordion as well as their names and a short description of their sound quality. Depending on the size of your instrument, you may not have all of these reeds available.