The Tritone, Substitution, Cycle 4
(22 Jan 04)
Tritone Symmetrical Voicings
Now let us discuss another class of chords who are symmetrical about the tritone.
Lets take our friend the Dom7b5. This chord contains 1 3 b5 and b7 if you move each of these up (or down) a tritone you get b5 b7 1 3 from the same root! This also means that since this new chord is up a tritone it could be called bV Dom7b5.
Once again you can move this down a half step and create the IV Dom7b5.
Now let us discuss Dom9#5 in a four note voicing with no root 3 #5 b7 9.
Moving this by a tritone yields b7 9 3 #5 so by the previous argument this becomes IV Dom7#5 by lowering a half step.
More special cases of Tritone Symmetrical Chords
The Dom7#5#9 with no root voiced 3 #5 b7 #9 displaced by a tritone becomes b7 9 3 13 from the same root. So lowering this chord a half step results in IV 13.
The Dom7b5#9 with no seventh, 1 3 b5 #9 displaced by a tritone yields b5 b7 1 13.
So down a half step yields IV 13b5.
Another special case
The Dom7#9 with no seventh 1 3 5 #9 up a minor third becomes #9 5 b7 b5, up a tritone becomes b5 b7 b9 13, down a minor third becomes 13 -9 3 1, all from the same root. Since this has similar symmetry to a Dim7 you can move down a major third or up a major second or down a half step to create Cycle four movement.
Down a half step > IV 13b5b9
Cycle:7+9>13b5b9>7+9>13b5b9
Up a major second > IV 13b9
Cycle:7+9>13b9>13b9b5>7+11+9
Down a major third > IV Dom7b5#9
Cycle:13b9>7+9>7+11+9>13b9b5
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