Accordion 101: How it works
Reeds. How do accordions work? In general, they are made up of a series of reed blocks, which look kind of like giant wooden harmonicas. An accordion can have up to six separate reed blocks, which sit in rows inside the treble casing, which is the boxy part of the accordion attached to the keys or buttons.
A reed block is usually long and tapers from a larger end to a smaller end. Each reed block has a series of reed plates, which are made up of a reed (usually steel but sometimes brass), and a valve (usually leather). The reeds and valves are usually held in place with beeswax.
In addition to the reed blocks in the treble casing near the buttons or keys, there is also what’s called a “bass machine,” which also uses reed blocks. These reeds are operated by a set of rods and levers, which attach to the buttons on the bass side of the accordion, on the opposite side of the bellows from the keyboard side.
This is why the accordion is often thought of as a one-man band instrument. It is played with both hands, and can play melody and chords/accompaniement at one time.
Bass Buttons. Generally, a player can see the keys or buttons on the treble, or right hand side of the instrument — but can’t see the base buttons on the left hand side. Because of this, the bass side gives the player a few clues to help navigate the rows of bass buttons on the left hand side. Often, a few buttons have some kind of tactile clue—either a rhinestone or an indented crosshatch pattern, or some other particular bump or marking that helps the player feel their way around the bass and chord buttons on the left hand side of the instrument (almost always the fundamental bass note C is dented. Commonly, fundamental bass notes E and Ab also have scratches or diamond studs too, although not always).
Players will also sometimes use “bass maps” when they’re learning the instrument, so that they can start to have some kind of visual representation of the bass keys in their head when they play. Bass maps/charts look something like this:
Bellows. While the intricacy of the keyboards and buttons may look impressive, the life of the accordion is the bellows–the “lungs” of the instrument–that make air flow through the reeds. Air is moved through the reed blocks by the action of the bellows, which is the middle part of the accordion that can expand and contract to push and pull air through the reeds. The bellows are usually made of paper. When the bellows are stretched or contracted, the reeds make some kind of sound. To move bellows without making sounds from the reeds, one uses a “air button” on the left hand side of the instrument.
Many skilled accordionists would emphasize the importance of bellowing; it’s the life of the instrument. Dynamics and articulation are controlled by the amount and pressure of the air produced by the bellowing action; quick, forceful bellowing would produce loud sounds, and slow, gentle bellowing would make soft sounds, for example.
Switches. An accordion can have more than one “voice.” On both sides of the bellows, there is a row of “switches” you can click on to choose a different “timbre,” or a particular quality of sound. The function of a switch is to open or close one or more sets of reeds. The more sets of reeds in an accordion, the more switches become available, created by different combinations of reeds in different registers, or octaves.
Different timbral options are created by combining sets of reeds that are tuned in different octaves, or registers. For example, for the right hand keyboard on a piano accordion, you can have up to four sets of reeds. Each set is tuned an octave apart. You can hear a different quality of sound when you hear only the lowest register set of reed as opposed to when you hear the lowest and the highest register sets of reeds sounded together. The switches can control what combination of these sets of reeds can be sounded together at the same time.
Sometimes, two of these sets of reeds can be in the same register, or octave — but slightly tuned apart from each other. This is called “musette tuning” or “wet tuning.” For example, one reed can be tuned to 440Hz, and another reed in the different set can be tuned 10 cents off from 440Hz. When you sound both sets together, it creates the rich vibration in the timbre (or “tremolo” effect). This sound is typical of French musette music, and favored by many folk musical genres in places including Mexico, Germany, Southwest Louisiana, Ireland, and Italy.