What perplexes me is how they relate to the key signature. As you say, the F blues scale works; the first three notes of the melody outline an Fm triad; the whole progression can be brought gracefully to rest on an Fm chord. But there’s no Fm anywhere in the progression. I notice you refer to F7 as the i chord.

I’m just fishing for a free lesson really! But if there is an explanation I’d be really pleased to know it.

Regards, John

The word “wrong” kind of doesn’t sit well with me. There’s room for either sound in there, and you aren’t deviating so wildly that you change the composer’s intent when you make that sub. Changing qualities or extensions to improve voice leading (or attain any other musical goal really) is pretty well within bounds.

I guess my analysis can be summed up as a possibly misguided attempt to map this into the 12-bar blues.

F7#9 Db13 | GbM9 B7b5 | Eb7sus4 Db13 | Eb7sus4 F7/C
Bb7sus4 Db13 | C7sus4 C7#5#9 | Ddim7 E/G | Db7 GbM9
B13 Bb7 | C7#5 Eb7#5 | F7#9 Db7 | GbM7b5 B7b5

My sus chords in bars 5 and 6 are wrong and your minors are right. The Gm in bar 6 for my money is one of the best sounds in the whole of the piece, but the I’m using the sus chords at the moment because they provide an element of chord melody. Looks like I go for a bit of a ramble in bar 7 too.

OK, so I know it’s in F minor because that’s what works. An extra couple of bars of Fm11 at the end of a solo makes a beautiful space before the next. My dumb question, though, is: how is it in F minor? There’s not an Fm chord in the whole of the progression and yet it’s implied throughout. Some advanced form of substitution … ?

Thanks again.