The "best" Replacement In This Context

D- b5 7/Ab

JamSession wrote:

D- b5 7/Ab

 

Ok, but it would be a second (practically II V), not exactly a substitution or am I wrong?

If we are talking about substitution, there should be a chord to replace... if I understood correctly, you need a chord (with A-flat in the bass) that connects C/G to G7(b9). Right?

Yes Dr

PS

Why "b9" in parentheses?

In fact, it could also be written without parentheses, but it seems to me that the practice is to put altered tensions in parentheses, while keeping the 7.

es: C7, C9, C13, C6/9, C7(#9), C13(#11,b9) etc...

Ok, Dr... but I didn't understand what you suggest for the replacement, which is the subject of the topic ...

mmm... something replaces something else. If you don't propose a first draft, what are we replacing with what? ;-)

: JamSession rightly proposed a DØ inversion and you said it was a second. true. but it's not clear what you meant.

just because it's late, try Gb∆ on Ab.

i like...

DrJellyfish wrote:

just because it's late, try Gb∆ on Ab.

Sorry, do you mean the 2 superimposed chords?

no, I meant Ab major7 with Ab in the bass: Ab13sus4.

Ah ok, I hadn't understood that it was a SUS and I still don't understand it now, just so we're clear.

Gb∆: gb bb db f with the addition of ab going to the bass

I would have written Gb∆9/Ab....that's why I didn't catch it immediately

Seeing it from this point of view Ab13sus4: ab db f gb omitting the fifth and replacing the third with the fourth, which should square with what I wrote before regarding Gb∆9/Ab

I would play it like this: A-flat in the bass and G-flat, B-flat, D-flat, F with the right hand. I didn't write Gb♭9 because in the chord played with the right hand there is no ninth, and the A-flat in the bass is not intended as the ninth of the G-flat. If we think of it as a slash chord, we write the symbol relative to the right hand, not including the bass; if we think of it as one single unit, A-flat is the root.

A13sus4 would be Ab(F), Db(sus4), Eb(5), Gb(7), Bb(9*), F(13). * it is not necessary to write 13,9 because the ninth should be implicit in a 13 chord.

As for voicing, I would keep the seventh and the thirteenth an octave apart (but it's a matter of taste) and by arranging the upper voices 7, 9, sus4 and 13, I obtain a ∆ chord, which already has its own sonority and is easy to memorize.

Regardless of the voicing, I like Doc's solution; one could almost put JamSession's chord and DrJellyfish's chord in succession, partly because we are coming from a somewhat poor chord

Ok, but what is the criterion for the proposed replacement?

The first thing that caught my eye, and also caught good old Frank's eye, is that the second turnaround is very un-jazzy; therefore, before thinking about the II degree (or VI minor, depending), I would think of a solution for that C/G. Then there is another aspect to consider: we don't know the melody, we don't know the tempo—is this piece a ballad, a medium, or an up-tempo..? What notes "sing" over those chords? Furthermore, is it a totally tonal piece or is it only tonal in this passage? These are all fundamental aspects to be able to give an exhaustive answer.

In general, if the piece is in a major mode, all the harmonies of the respective degrees of the minor mode work for us; this is an axiom that also applies to classical music. The principle based on which we use an Ab bass instead of a D bass is the famous tritone substitution; the theoretical steps are as follows:

1) on the II degree, there would be D minor seventh of the second species

2) by raising the third, it becomes D dominant seventh, which is a secondary dominant

3) on this, we apply the tritone substitution, from D7 to Ab7, the principle of which is that the chords are interchangeable because the third of one is the seventh of the other chord and vice versa, for all the enharmonic complications...

4) and here we notice Dr. Jellyfish's "touch of class": we substitute Ab7 with Absus13, because by doing so we remove the C from the chord, which is a banal note since it is already in the key of C, and we introduce Bb and Db, which are notes far from the key of C and therefore create that interest, that sense of harmonic openness desirable in jazz.

in theory everything is fine, but in practice there are those aspects I mentioned earlier that cannot be ignored...

Thanks for the nice explanation Geppino!