Hi Matt - I think we did this before - let's do it again. There are four possible alt chords - 7b5b9, 7b5#9, 7#5b9, 7#5#9. So in my mind the alt chord is not a specific chord, but a family of chords. So I'm always wondering when I see it which of the four is being specified.

I made a BIAB song with the above four chords in C, plus C Alt, plus C Maj using PNOSIMP4 style. BIAB correctly played all, and for C Alt played a C7#5#9. So, that suggests how BIAB interprets C Alt.

So when one sees C Alt in sheet music (or fake book), how does one know what the composer/arranger had in mind, I ask. Don't say "It's up to me".

Interestingly, I just tried these chords out in PGMusic's Piano Chord Dictionary and it plays C Alt as - C E Gb G# Bb Db D#, or a composite of both # and b 5 and 9.

kelso

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