Name that chord!

[3*s]

This has been bugging me for a bit.

F#, A, C, Eb, G#

It transitions really nicely into Cmajor.

At first glace it looks like dim7(add 9) or something like that, but most theory sources seem to insist the ninth of a dim7 is the root (eg F# in this case), and therefore doesn't technically exist as it's own tone. So that makes the G# a ##9, or b10 or something. The F# is definitely the bass note.

Can any theory experts or people with a big book 'O chords give me a name for this?

[Gregjazz]

Yes, it is a dim7(add 9), especially if you're certain the F# is the bass note. There is no such rule that the ninth of a dim7 is the root.

It's very simple: the dim7(add 9) chord is made of tones from its scale, just as all chords are. The dim7(add 9) chord comes from the whole-half scale, which in the context of the F#dim7(add 9) would be: F#, G#, A, B, C, D, Eb, F

This is nothing unusual that you describe.

[3*s]

Thanks greg.

One thing though, the G# seems to be the 10th note of the whole diminished scale, so wouldn't it be dim7(add 10)?

[nuffink]

Thanks greg.

One thing though, the G# seems to be the 10th note of the whole diminished scale, so wouldn't it be dim7(add 10)?

The numbering system gets a bit sketchy when you try to apply it to 8 note scales.

[herodotus]

Thanks greg.

One thing though, the G# seems to be the 10th note of the whole diminished scale, so wouldn't it be dim7(add 10)?

The numbering system gets a bit sketchy when you try to apply it to 8 note scales.

Especially when they are internally symmetrical, and therefore, strictly speaking, atonal.

A much better way of discussing such chords can be found here, though how they fit into diatonic tonalities is a tricky (and neglected) subject. For example, the chord in question, which sounds so good transitioning to c major, is in fact in a different transposition of the diminished scale: {b, c, d, d#, f, f#, g#, a, b} than c major is : {c, c#, d#, e, f#, g, a, a#, c}, so go figure.

In other words, unless you want to write a book (which will have about 3 readers if you're lucky), don't worry about the names.

Debussy didn't.

[Gregjazz]

Thanks greg.

One thing though, the G# seems to be the 10th note of the whole diminished scale, so wouldn't it be dim7(add 10)?

You have a good point, but chord-wise it is referred to as the 9th.

The sequence of the chord goes like this:

F# (root), A (3rd), C (5th), Eb (7th), G# (9th), B (11th)... and that's as far as I've seen people play on a dim7 chord.

Chord numerals sort of assume you're using a 7 note scale.

[Gregjazz]

Reminds me, a while back I wrote a Bach-style invention using only notes from the G half-whole scale... that was fun to write, especially trying to make it's diminished-ness unapparent.