I was looking around the website of one of the most important maker of harmonica and I checked the tuning chart of an harmonica in the A key.
I am beginning to study harmonica and expected to find on the holes from 4 to 7 the scale of A. When playing a harmonica in C I get the scale of C major, so I was half expecting to find A major or (maybe) some bluesy variation on it.
This is the tuning of an A harmonica, starting from hole 4, till hole 7:
A4 - B(H)4 - Db5 - D5 - E5 - F#5 - Ab5 - A5
With equal temperament, these pitches, would correspond, of course, to those that I was expecting (Three sharps: F#, C#, G#).
They mention that this harmonica features a "modern compromise tuning": note that I find it to be the same for the classic model of the harmonica so the compromise must be somewhere else (maybe the temperament is not equal?). They market the Crossover type of harmonica as more versatile, and I have no doubt that this is true: does this versatility depend on this choice of the notes?
And most of all: why the peculiar choice of names for the notes? Why calling it Db5 instead of C#5? Why Ab5 instead of H#5 (btw, in the scale of A one would naively expect that A is not lowered or raised)? I suppose that this kind of tuning must be in some sense natural but I need some help to figure out why is it so.