Accordions come with various key-note systems. For instance, a garmon may contain one or two rows of buttons each producing two notes from the diatonic scale when expanded or contracted by bellows expansion or contraction.
An organ is typically equipped with three to five rows of treble keys arranged a fifth apart to play melodies and twelve unisonoric bass buttons for rhythm and harmony.
Keys
Diatonic accordions differ from their chromatic counterparts by having only notes from one scale, such as C (no flats or sharps) or G. Chromatic accordions feature every note in every scale, including sharps and flats, giving them greater range in key playing.
Two row diatonic accordions feature a second row of buttons either one semi tone higher or one perfect fourth above its first row, providing extra notes from relevant diatonic scales as well as providing an accidentals row that changes depending on bellows direction.
Three row diatonics are very similar, with the third row often one full tone higher than the first and an accidentals row which changes with every bellows movement. Common four and five row diatonics also follow this format.
Origins
Accordions were once widely played instruments at home, churches, dances, theaters and front porches – not to mention being mobile enough to be played as street musicians or country folk artists.
One-row diatonic accordions (or melodeons, as they’re sometimes known) consist of 10 buttons in each row tuned to an unmodified scale without sharps or flats; on the other hand, chromatic accordions allow players to play any note in any scale with just one movement of their bellows.
Both types of accordions can be seen in many traditional musical genres, including Zydeco, Tex-Mex and Irish trad. Some styles require specific accordions in order for their music to sound right – typically because certain keys or sets of keys require diatonic accordions for optimal playing.
Construction
Diatonic accordions typically feature a single-action keyboard with buttons that produce distinct notes when bellows are pushed or pulled, enabling players to create melodies as desired but restricting their play to just one key at once.
Some accordions feature double-action keyboards and operate like harmonicas. Examples include the Russian garmon, Steirische Harmonika (found in Alpine regions such as Germany, Austria, Slovenia and South Tyrol) and Basque Trikitixas.
Other accordions feature a bisonoric keyboard. One such instrument is the melodeon, with up to three treble rows and two bass rows; it can be found across a range of musical genres including traditional English and Irish music and is easy for beginners to learn.
Styles
There are various styles of diatonic button accordions. Some, such as the garmon (the Basque country’s national instrument) feature double-action buttons which produce two notes when pushed – this allows full diatonic scale playing from four buttons on the melody row.
Other instruments, like the melodeon, feature single-action mechanism which produces one note per push/pull of its bellows. This provides 10 notes to be played using right hand, including diatonic scales and major chords in multiple keys.
Fully chromatic button accordions provide greater range through using separate reed sets on each bellows, making for more complicated playing but yielding a richer sound – ideal for folk and traditional Irish music.
Accessories
Diatonic accordions offer lighter reeds that cover only 1-3 keys, making it suitable for many styles of music, especially folk and traditional genres requiring specific accordion types.
Melodeon keyboards tend to feature diatonic scales with one or two rows of buttons each producing notes from that particular scale. Most models also offer an optional partial third row which contains relevant accidentals.
Another key difference between diatonic and chromatic accordions is their use of all 12 notes of the scale, including sharps and flats. Unfortunately, this means more reeds must be supported by larger boxes resulting in four times heavier accordion weight compared to its diatonic counterpart – something to keep in mind when selecting accordions for specific music genres or styles.