G'day again 24½ months later,

I looked through this thread because it was linked in Foolestroupe/Robyn Hayes' rather schlolarly thread:
Piano Accordion: for the Recycled Musician.

One thing I noticed was that the confusion (& "folk etomolgy" ... ) about the meaning and derivation of diatonic had not been cleared up. Most of the problem comes from approximations of Latin suggesting "di(a)" means (~) "two". It does not - the Greek meaning is "through" ... so diatonic should mean "through the tones" - but it really means "through the notes, or, as in my Concise Oxford, "... involving only notes proper to the prevailing key without chromatic alteration ...".

This means it has only the "natural" notes of one "key" (or "scale"). Any additional notes are "chromatic" in that they add additional "colours" ... the semitones that are needed for constructing other keys" or "scales.

This means that the basic layout of 9 - 11 buttons per row is "diatonic" ... even though the next row - or the button at the end of that row - may have additional semitones. The typical 3-row button accordion imported into Australia has half a dozen 'semitones' on the 3 rows - plus a few more across the adjoining rows. One of these can (with lots of manoeuvring) play nearly 2 octaves of fully chromatic scale ... and, maybe, John Kirkpatrick actually does ... but very few others do! As the arrangemment is not intrinsically for playing chromatic scales, rather for adding occasional semitones, it is still fair (if confusing!) to call such accordions diatonic.

Since the adjoining (~ diatonic) rows, at semitone intervals, of a "British Chromatic" are intended to be played chromatically ... the name "chromatic" is fair enough for these instruments - despite their "diatonic" format.

I hope that hasn't just confused you ...

Regard(les)s,

Bob Bolton