Blues Turnaround Using Upper Pedal Point (In A Mellow Tone/Jazz Blues)

I discovered this turnaround while learning "In a Mellow Tone."  The last two bars of the form turn around to the first chord of the form (Bb7), or Ab6 G7/Gb7 F7/Bb7.  The first chord of the turnaround Ab6 is the trickiest.  I first noticed it is the bVII of I, but then I saw that an Ab6 triad is also part of a Bb9 chord, meaning Ab6 is closely related to the I in a I-VI-ii-V turnaround. So far so good.  G7 is the VI of Bb7, so that is straightforward.  Gb7 is just a tritone substitution of the ii of Bb7, Db7.  And F7 is the V of Bb7.

This sounds cool on its own, you get a moving chromatic descending line from the Ab to the F.  But I thought what if you pedal the Ab?  How does that change/reharmonize the chord qualities?  You'd get Ab6->G7b9->Gb9->F7#9->Bb7.  Pretty cool!

If you want to add in one more cool concept, play a rootless F7#9 and keep the shape identical but move everything down a half step...you get Bb13!  Keeping the intervallic distances/symmetry constant across two chords can be really effective.

In addition to chords for comping, can also create a solo based on the architecture of the chords

Of course you can just play straight descending dominant 7ths..

This is a great turnaround that can be used in "In a Mellow Tone" or any jazz blues turnaround that resolves to a dominant chord.  You can even try it resolving to a major 7th chord...