There is lots of stuff you can do on the B section. You can tritone sub every other chord for a chromatic movement.
The original progression: D7,G7,C7,F7
Tritone sub variation: D7,Db7,C7,B7
Tritone sub varation 2: Ab7,G7,Gb7,F7
Basically, you can tritone sub any of the dominant chords in the B section. Experiment and find combinations you like.
It is also common to make these V7 chords into II-V's.
Vanilla: Dm7 G7, Am7 D7, Gm7 C7, Cm7 F7.
You can apply the same principle to these II-V's with tritone subs. Just play the II-V a tritone away. These have more movement, so not all combinations will be as pleasing. Experiment, and your ear will guide you to where tritone sub II-V's sound the best to you.
These subs open up the possibilities for both comping and soloing on the otherwise dull B section. |