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2.2.3 Tritone/4ths chords
Made up of a perfect fourth over a tritone interval, they are akin to
quartal chords but have even greater harmonic potential. A tritone/4th
voicing is capable of expressing at least 8 harmonies. Here is a list
with A7 13 as the point of departure:
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G C# F# can be:
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with bass:
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1
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A 7 13
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A
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2
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Eb- 6 9
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Eb
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3
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E, G, Bb, Db dim
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E, B
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4
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Bb #9 13 b13
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B
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5
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Eb 7 #9
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E
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6
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Db- 7 b5 11
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F
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7
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F b9 9 b13
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F
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8
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F# b9
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F#
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Tritone/4th voicings have a smart, jazzy sound due to their open configuration, the tritone, the fourth and the half-tone friction between the top and lowest note. Their salient feature is that a half-step slide up or down moves the harmony 1 step up or down in the Circle.
| One-half step slide moves 1 step up or down the Circle: |  |
| A cadence in F: |  |
| Note the first 2 entries in the preceding page's list: the same tritone/4th voicing can stand for II and V7, here E- , A7 with basses E and A, respectively. |  |
| With a tritone/4th voicing in the left and 2 fourths in the right hand, one and the same chord stands for II7 (11) and V7. Bottom notes are 3rd and dominant-7th, respectively. Hear it with basses C and F. Truly minimal motion! |  |
Another great feature of the tritone/4th voicings is that with a parallel slide half-step up or down they switch between the key's minor and major mode, here shown in the left hand:
| Lowest note is the 3rd. |  |
| Another parallel half-step slide of tritone/4th chords toggles between diminished and dominant-7th of the same key, but now the lowest note is the 7th: |  |
This leads to the third entry in the list: tritone/4th voicings can be diminished chords. In diminished harmony, everything repeats every minor3rd step (see Part 2, section 5).
| Therefore tritone/4th voicings played with their lowest notes a minor 3rd apart (plus an octave), or a multiple of 3rds apart, render spicy diminished chords: |  |
| The hands' movement need not be parallel: |  |
See Part Two, Chapter 5 for more on tritone/4th voicings in diminished harmony. Tritone/4ths are truly magic voicings. Bill Evans favored them in his playing.