I know how to write the key signatures for any note within the 12-note chromatic scale. I know this doesn't come up very often, but what are some ways to write out key signatures for passages of music in a key center based off of a quarter tone?
For example, I know A major has 3 sharps. What would a key signature look like for A half-sharp major?
- I considered simply notating something like "A=453hz" and writing in A, but shifting between tuning systems can get a bit unwieldy (especially if performing on a real instrument) and I'd rather avoid that.
- I considered having three "3/2 sharp" glyphs on F, C, and G, and placing a "1/2 sharp" glyph on D, A, E, and B. I noticed, though, that under this system, every microtonal key signature has seven accidentals in it, and a lot of them have "1/2 sharp" and "1/2 flat" signs in the same key signature (example: G 1/2 flat major).
- I also considered shorthanding them, writing "3/2 sharp" glyphs on F, C, and G, and leaving the other notes with nothing. One advantage of this is that the visual look of A major is preserved, with the three sharp-ish accidentals, and the performer would know that all the other notes logically must be 1/2 sharp. It would be like reading a normal key signature, then seeing the altered accidental and deducing that everything is a quarter tone flatter than A major.
- I'm open to other suggestions (as long as they use some form of microtonal key signatures) as well - there's probably a better system out there that I haven't discovered.