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Tritone Substitution

PostPosted: Thu Apr 16, 2009 2:55 pm
by strachs
Not much has been said in here about tritone substitution. I know you jazzerz are often into this, as a way to change a chord prgression, but maintain functionality.

The concept offers a cool perspective on this ... just look at the AMG's proposed for 7th chords (PMG II). A direct substitute for II is +V, the tritone counterpart of II. Another common "home" for a 7th chord is on I, and it's tritone counterpart (+IV) is also listed as an AMG.

What I find neat, too, is that all of the "out" tones become "in" tones in the tritone-related parent scale.

For example, a popular chord in funk is 7#9, and equally popular is a 7th chord with an added sixth (providing dissonance, or color, without straying out of the 7TO).

These chords are actually tritone counterparts.

The 7#9 chord is often voiced on the piano like so (RH, over C in the bass):

D# (#9)
Bb (b7)
E (3)

These same notes are the 7/6 chord in C's tritone counterpart, F#:

D# (6)
A# (3)
E (b7)

All kinds of correspondencies can be found when we realize that each Lydian Scale tone has a tritone counterpart in the "outside" world:

1 - #4
2 - #5
3 - b7

5 - b2
6 - b3
7 - 4

Anyone have some insights to contribute on substitution?