Diatonic button accordion
A melodeon or diatonic button accordion is a member of the free-reed aerophone family of musical instruments. It is a type of button accordion on which the melody-side keyboard contains one or more rows of buttons, with each row producing the notes of a single diatonic scale. The buttons on the bass-side keyboard are most commonly arranged in pairs, with one button of a pair sounding the fundamental of a chord and the other the corresponding major triad (or, sometimes, a minor triad).
Classification
412.132
(sets of free reeds)
Diatonic button accordions are popular in many countries, and used mainly for playing popular music and traditional folk music, and modern offshoots of these genres.
Action[edit]
Most diatonic button accordions have a "single-action" (or bisonoric) keyboard, meaning that each button produces two notes: one when the bellows are pressed or pushed (closed) and another when the bellows are drawn or pulled (opened). In this respect, these instruments operate like a harmonica.
(In contrast, most other types of accordion, for example piano accordions and chromatic button accordions, are "double-action" – or unisonoric – because each key produces a single note regardless of bellows direction.)
Other single-action or bisonoric members of the free-reed family include the German concertina, the Anglo-German (or "Anglo") concertina, the bandoneon, the Chemnitzer concertina (see concertina) and the mouth organ (harmonica).
There are varieties of diatonic button accordion that are double-action, such as the garmon.
Bass systems[edit]
Traditionally, one-row instruments have two or four buttons on the bass side, two-row instruments have eight, and three-row instruments twelve. As mentioned above, bass buttons are conventionally arranged in bass-note/chord pairs.
Some modern players, particularly in France, are driving a trend towards instruments with more complex bass systems, with as many as 16 or even 18 buttons. Sometimes these more elaborate systems will diverge from the single-action principle, and may feature bass notes only instead of bass-chord pairs of buttons.
The B/C/C♯ system (also known as the British Chromatic System) used in Scotland provides a notable example of the use of a double-action bass side with a single-action melody side: these instruments frequently feature a full Stradella bass system as used on piano accordions and chromatic button accordions.[9]
Geographical variations on the DBA theme[edit]
Several distinct variations of the DBA have developed in different regions of the world. These include the Russian garmon, the Steirische Harmonika[notes 1] or Slovenian-style accordion that is popular in Alpine regions of Europe, the Swiss Schwyzerörgeli and the Basque trikitixa; the last two combine single- and double-action (bisonoric and unisonoric) features. A common type of Italian organetto has a single melody row augmented with a very short half-row of between two and four buttons (often smaller in diameter than those on the main row) providing reversals only.
Advantages and disadvantages of the diatonic system[edit]
DBAs have two main advantages when compared with chromatic accordions such as piano accordions and chromatic button accordions: 1) smaller size and lighter weight, 2) and the rhythmic effects inherent in the single ("push-pull") action.
The size and weight difference results from the nature of accordion reeds, which produce sound when air is moved through them in one direction only. In other words, for any key or button, two reeds are necessary: one to sound on the press, and one to sound on the draw. Because a double-action instrument sounds the same note on both press and draw, it needs two reeds for any given note in its range, where a single-action instrument—which sounds a different note on press and draw—requires only one. Any double-action instrument thus requires roughly twice as many reeds as an equivalent single-action instrument, making it larger and considerably heavier. (Another way to understand this difference is to consider the fact that a double-action instrument generally requires twice as many keys or buttons to produce a range of notes as a single-action instrument: for example, a piano accordion requires 8 keys (16 reeds) to sound a diatonic scale from C to C', where a DBA pitched in C requires 4 buttons (8 reeds) to produce the same notes.) This size and weight advantage is somewhat eroded in more complex, multi-row variants of the DBA, alluded to below.
The rhythmic effects inherent in the push-pull action are very well suited to the lively rhythms of dance music, and traditional dance music in particular. (On multi-row fourth-apart instruments, players can to some extent counter the natural push-pull effect with a row-crossing playing style that "smooths out" the musical phrasing; on semitone-apart systems, depending on the key of the piece being played, players may be obliged to adopt a smoother style.) Additionally, the close-togetherness of the notes on a DBA allow some tunes (particularly the quick folkdances and tunes written for the instrument) to be played with more ease and speed than on the more spread-out keyboards of chromatic- and piano-accordions. For example, playing an Irish reel might be easier on a B/C system diatonic than on a piano-accordion, and a Swiss Schottisch or Ländler might be easier to play on a Schwyzerörgeli than on a piano or even a chromatic due to the chordal/arpeggio phrases that fall naturally on the buttons that are arranged thus.
The main disadvantage of the diatonic system is that playing in a wide range of keys is impractical. Attempts to overcome this limitation, for example by adding extra rows and more complicated bass systems, invariably add extra bulk and weight, thereby compromising an advantage in striving to overcome a disadvantage. Extreme examples are 18-bass three-row instruments of the type favoured by some French musicians, and B/C/C♯ accordions with 120-button Stradella basses: the size and weight of both these types can be greater than medium-sized piano or chromatic accordions.