What scale do you play over V7#9?

Question

In Mark Levine's Jazz Theory Book (section about tritone substituion), he says (paraphrased):

When the tritione substitution contains the 7th in the melody, 

you can add a #9 to the chord.

So a Bb7 is replaced with a E7#9, where the #9 is a G, major 3rd G#

Which would give you V7#9 a tritone up from the V in a ii - V - I.

I don't remember him talking about a mode this chord belongs to?

Is this the same as a V7b9 using the half-whole dim scale?

What mode best fits this chord? Assuming "best fit" is similar to playing Mixolydian on a Dominant Seventh.

Answer 1

The E half-whole diminished scale would work, but it's probably not the first choice unless you're specifically looking for that diminished sound. I'll stick with the example you described, where the progression B♭7 – E♭Maj is being played with a tritone substitution: E7♯9 – E♭Maj. Here are some chords that will sound good over E7♯9:

• E Altered scale: E F G A♭ B♭ C D E (this is the 7th mode of F melodic minor)
• E Phrygian ♭4 scale: E F G G♯ B C D E (this is the 3rd mode of C harmonic major)
• E Diminished scale: E F G A♭ B♭ B D♭ D E
• E Phrygian Dominant scale: E F G♯ A B C D E (this is the 5th mode of A harmonic minor)
• E Mixolydian ♭9 scale: E F G♯ A B C♯ D E (this is the 5th mode of A harmonic major)

The harmonic major scale is less common but has some really cool sounds. This video provides a nice overview of the harmonic major modes.

Something worth pointing out is that, if you want, you can think of the E Altered scale as B♭ lydian #4 (the fourth mode of F melodic minor). These two scales have the exact same notes. Another thing to mention is that the E Mixolydian ♭9 scale & the E Phrygian Dominant scale don't contain the ♯9 note (i.e., don't contain a G). These scales would still sound good over E7♯9, but if you're sticking strictly to the scale then you'll be missing that ♯9, which is probably in the melody if ♯9 is written into the chord. One simple solution is simply to add the ♯9 into the scale whenever you want to reference the ♯9 note. Doing this could be important if you want to reference the melody. The ♯9 often appears in chord symbols because the note is being played in the melody.

All of these scales would also sound great over an E7♭9 chord.

Answer 2

I like to use the Jazz minor (which is the same as the ascending Melodic Minor, the Major scale with a b3) of a half step above, it always works (e.g. for a D7+9 play an Eb Jazz Minor where the root of your chord is the major 7 of the scale). Let me know what you think.