The Mechanics of the Irish Button Accordion: Everything You Need to Know

The Irish button accordion is a complex instrument with many working parts. To get the most out of your instrument and learn how to care for it properly, it’s important to have at least a basic knowledge of how it works.

It’s also incredibly helpful (and wise)  if you’re in the market to buy an accordion to become familiar with the terminology used. 

This handy guide will reveal the mysterious inner workings of the accordion and help you get to know the ins and outs of the Irish button accordion.

The three most important components of the accordion are the bellows, the keys or buttons and the reeds. But how do they all work together to produce that unique, instantly recognisable sound?

Keep reading and I’ll share in depth information that will equip you to make confident, informed purchases. 

You’ll learn about the interior mechanics of the accordion – including the ever important reeds. I’ll teach you the difference between wet and dry tuning and explain the accordion voice. What is a multi-voice accordion and how many voices do you need to play traditional Irish music? Keep reading to find out the answer to these important questions, and more. 

Your newfound knowledge will also help boost your playing and give you a unique insight to how this much-loved traditional Irish instrument makes such great music. 

What Is an Irish Accordion?

If you’re in the market to buy an Irish button accordion and find yourself researching or shopping online, you’ll notice there’s an abundance of information relating to accordions of all styles, shapes and sizes. 

The Irish button accordion is frequently referred to as a two row diatonic accordion.

Though an Irish button accordion is a fully chromatic instrument, the term chromatic accordion usually refers to the classical button accordion or ones used for other genres of music such as jazz. 

You’ll also occasionally see the Irish button accordion referred to as a two row melodeon. This is not to be confused with the one row, ten button melodeon which also commonly features in traditional Irish music. 

The two row Irish button accordion features an outer row of buttons in one key, with the inner row tuned in another key, just a semitone higher. This configuration makes all the notes of the chromatic scale available. 

Irish accordions are typically tuned to B/C or C#/D. Learn more:

Which Accordion Key Is Better For Traditional Irish Music – B/C or C#/D?

Learning to play the Irish accordion can be a costly endeavour. Button accordions are some of the most expensive instruments in the world of traditional Irish music. A good quality beginner accordion will cost upwards of €500 while intermediate accordions start at closer to €1,000. Advanced accordions can cost several thousand depending on which make and model you buy.

To learn more, why not check out these handy guides? The Beginner Irish Accordion Buyer’s Guide

The Accordion Body: Inside and Out

Let’s start at the very beginning (a very good place to start). I’ve put together this simple diagram outlining the basics. Take a look:

mechanics of the irish button accordion - diatonic two row accordion anatomy diagram

The body of the accordion consists of two wooden boxes or frames, joined together by a bellows in the middle. 

The bellows are the lungs of the accordion. They’re usually made from pleated cardboard and cloth, reinforced with leather and metal and connected to the casing or frame on either side of the accordion. 

accordion bellows

Compressing or pushing the bellows creates air pressure, while expanding or pulling it creates a vacuum. When the player presses the buttons or keys, air passes through the reeds causing them to vibrate which in turn produces sound.

The bellows control all the dynamics and articulation. 

When not in use, the bellows are held in place by two bellows straps – one placed on top of the accordion and the other underneath.

Interior Components

accordion reed and valve

Valves are the padded bars which open and close sound holes and are operated by levers, from the keys or buttons. These sound holes are located on the right hand of the instrument (as the player holds it), under the grille.

Accordions produce sound through the use of reeds. The reeds are housed inside the casing of the accordion and organised into sets of reed banks

The reeds are made up of metal strips that are riveted to either side of a rectangular metal plate. Below the reed is a slot which allows air to flow through the bellows.

mcneela button accordion interior - reed banks

The quality of the reeds is one of the factors that has the greatest impact on the sound the accordion produces. The playability, sound and quality of an accordion all depend on the reeds that it’s fitted with. 

Reeds come in four different quality levels: handmade, tipo a mano, hand finished and commercial. 

Learn more about the intricacies of accordion reeds and how they affect the sound in my Intermediate Guide to the Irish Accordion.

Exterior Features

The Buttons

The fingerboard houses the buttons or keys that are used to play the melody or tune with the right hand. Irish button accordions typically have either 21 or 23 buttons.

What’s the difference? A 23 button accordion has two more buttons at the low end of the fingerboard, offering four additional notes. More notes means increased range which can offer more options for you playing. But don’t worry, a 21 button accordion is also sufficient for playing traditional Irish music. 

Button accordions for traditional Irish music typically feature flat fingerboards. Stepped fingerboards can also be used however. On a stepped keyboard or fingerboard, the inner row of buttons is simply raised higher than the outer, either using a stepped layout or gently sloping fingerboard.

Traditionally, two row Irish button accordions have eight bass keys, situated on the opposite side to the fingerboard. They are played with the left hand and used to accompany the melody played in the right. 

Most accordions feature an air button, located near the player’s left hand, which allows the player to let air in or out of the bellows silently, without producing any sound.

Fashion & Function

Each side of the accordion is covered with a grille in order to facilitate the transmission of air in and out of the instrument, and to allow the sound to project better.

The treble or right hand grille covers the fingerboard’s treble valves and mechanisms. It’s used to decorate the accordion, and usually displays the brand name and/or the logo of the manufacturer. The grille can be vented to allow a louder sound, or alternatively it can be used as a muting mechanism.

accordion grill and register switch stop

Switch It Up

A switch (also referred to as couplers, registers or stops) is a button near the fingerboard, which, when pressed, causes a different set of reeds or voice to be activated. Alternatively, they can also be located on top of the accordion, above the treble keyboard.

Using the switches, an accordion player can mix and match different reed blocks with varying octaves and registers to produce various sounds. You can fully control the timbre and sound quality of the notes.

Many advanced accordions also feature a bass switch on the left hand side which removes the third from the chords played by the bass keys. 

Support Features


Depending on the weight of the accordion, most models come with either one or two shoulder straps. These help to secure the accordion in place and redistribute the weight of the instrument to allow for more comfortable and secure playing.

You should note that shoulder straps are there to hold the accordion in position, and should not be used to bear the weight of the instrument. 

Despite popular belief, back straps are unnecessary if the accordion is being held in the right position. In reality, they can actually increase the load on a player’s back and shoulders. Most teachers advise against using them for this reason. 

Older accordions sometimes feature a thumb strap attached to the fingerboard. You might find it limits the movement of your right hand somewhat, but using it or not is a personal preference. Most modern instruments feature a thumb groove on the finger board instead, which allows for ease of movement. 

All models will feature a bass strap, which is positioned over the wrist, providing a support for the left hand while playing the bass buttons, enabling the player to move the bellows in and out.

The Accordion Voice

Accordions can have more than one ‘voice’. Voice simply refers to the number of metal reeds fitted to the treble side (right hand side) of the instrument.

When a single key is pressed on the treble end of an accordion one or more reeds are sounded to produce the note. The number of voices which sound for each note refers to the number of reeds which are sounding at the same time. 

Thus, a two voice accordion will have two reeds sounding for each single key press. A three voice accordion will have three reeds sounding for each key press, and so on. 

These voices are controlled using  the switches (also known as couplers, registers or stops). 

Using these switches or stops, an accordion player can produce different sounds in varying octaves and registers. An accordion that is described as octave tuned for example will have one voice tuned an octave higher than the middle voice, and another voice tuned an octave lower.

Paolo Soprani Jubilee IV Irish music button accordion
Difference in Voice Qualities Explained

One Voice
Single voice accordions are usually light and compact.  They produce a bright, clear sound, akin to a concertina.

Two Voice
Two voice accordions are the most commonly played. Both reeds for each note are typically tuned to be very nearly, but not quite, at the same pitch. Usually one reed is tuned to concert pitch and the other is tuned slightly sharp. This slight difference in pitch causes the tremolo effect characteristic of the traditional accordion sound.

Three Voice
The setup on a three voice accordion is usually referred to as LMM (low/middle). The low or L reed, tuned an octave lower than the M reed, adds a deeper, richer sound to each note. 

Four Voice
The setup on a four voice accordion is typically LMMH. The H voice is tuned an octave higher than the M reeds and adds a bright, crisp tone to the overall sound. With all four voices in use, these accordions produce a rich, powerful sound.

The number of voices an accordion has will affect its cost. More voices = more reeds = higher production costs = higher retail price.

Dry vs Wet Tuning

The reeds in an accordion can be tuned in different ways.

If the reeds are tuned in unison, producing exactly the same identical pitch, the accordion is dry tuned

If the reeds are tuned differently however, with one or more tuned slightly sharp (higher) while the other is tuned to concert pitch the accordion is said to be wet tuned. (Concert pitch is A tuned to precisely 440 hertz.)

Wet tuning produces a tremolo effect.

Tremolo is the sound effect produced when two ‘identical’ notes have a slightly different pitch (ie one is tuned higher than the other) causing an acoustic vibration to be heard.

Wet tuning or tremolo tuning tends to produce a rich, heavy, loud sound:

Dry tuning produces a bright, crisp sound that, while usually quieter in volume, can also sound quite piercing:

Wet tuning is less fashionable in Irish  music these days however. Most modern Irish button accordion players play accordions with swing tuning. Swing tuning lies between wet and dry tuning and offers the best qualities of both. It’s ideal for playing traditional Irish music.

To learn more about which tuning is right for you, have a read of my Intermediate Guide to the Irish Accordion.

Continue Your Accordion Journey

Now that you’ve all that accordion information under your belt, are you dying to test your knowledge?

Why not take a look through our selection of button accordions, piano accordions and melodeons with your new expert eye and see if one is right for you? Our accordion store has something to suit all budgets. 

Beginning the Irish Accordion? Read This Before you Buy

Our in-house accordion and melodeon experts are also on hand to answer your accordion related questions. Simply leave a comment below or get in touch with us via our Contact Us page.

[Cairdín image: Michael Stokes, CC BY 2.0]

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  1. I’m 70 and want to have an exercise which is musical. I’ve never played anything before except the harmonica. What would be a good button accordion instrument to start with?

    1. Hi Marty, I thoroughly commend your plan! I think our 21 button grey accordion would be a great place to start. It also comes with free accordion lessons (launching early spring 2023) with one of Ireland’s leading accordion players, Benny McCarthy. Get back to me if you’ve any other questions at all.

  2. Do you buy instruments ?
    I have an old grey Paolo Soprano bought s/h in 1964. B/C with 2 couplers
    In great condition.
    I would love to know what year it is & its value.
    I don’t play it anymore.

  3. Thankyou for all the explanations on the different types of accordions, it was a big help I have the B C Mcnella and am enjoying it.

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