Apologies for such a newbie question. I'm learning English Concertina as my first musical instrument and trying to gain a better understanding of the accidental buttons and playing in keys other than C major/A minor.
On a piano keyboard, many of the white keys have a black key on either side of them - they could be said to have both a flat and a sharp adjacent to them. On the EC keyboard, there is only one accidental adjacent to each natural. Sometimes it is a sharp, sometimes it is a flat. My question is, what is the logic behind whether a particular accidental is flat or sharp?
For example, the accidental next to A is A flat. If, for the sake of argument, I wanted to play a tune in the key of B major, I would need an A sharp. I guess the answer is to use the nearest B flat key instead. Or am I missing something?