Tritone substitution

In jazz music, a tritone substitution is the use in a chord progression of a dominant seventh chord (major/minor seventh chord) that is three whole steps (a tritone: 6 semitones) away from the original dominant seventh chord. For example, Dmusic|flat7 would be the tritone substitution for G7 while F would substitute for B, and Gmusic|flat for C. Tritone substitutions are also used in improvisation and are commonly used to create tension during a solo.

The reason these dominant seventh chords may be substituted for each other is that they share the two pitches that form a tritone in each chord (the third and seventh, albeit reversed). In a G7 chord, the third is B and the seventh is F. In the Dmusic|flat7 chord, the third is an F and the seventh is Cmusic|flat (enharmonically B). Note that the interval between the third and seventh of a dominant seventh chord is itself a tritone.

One of the most common usages of the tritone substitution is in the 12 bar blues. Two 12 bar blues patterns appear below. The first is one of the more simple forms of 12 bar blues. The second shows the chord progression with a tritone substitution in measure 4. The tritone substitution is one of the most common substitutions found in jazz and was the precursor to more complex substitution patterns like Coltrane changes.

The 12-bar Blues and The Tritone Substitution

This is a representation of a simple 12-bar blues pattern in 4/4 time:

I IV I I IV IV I I V IV I I
C | F | C | C | F | F | C | C | G | F | C | C
The following is the same 12-bars incorporating a tritone substitution (sub V) in measure 4; that is, the Gb7, which is three whole tones away the root, C:

I IV I I bV7 IV IV I I V IV I I
C | F | C | C Gb7 | F | F | C | C | G | F | C | C

The second common usage of the tritone substitution is in ii V I progressions. This substitution is particularly suitable for jazz because it produces chromatic root movement when applied to the ii-V-I progression that forms a basis of jazz harmony. For example, in the progression Dm7 - G7 - Cmaj7, substituting Dmusic|flat7 for G7 produces the downward movement D - Dmusic|flat - C in the roots of the chords, typically played by the bass. This also reinforces the downward movement of the thirds and sevenths of the chords in the progression (in this case, F/C to F/B to E/B).

Tritone substitutions are also closely related to the alt chord used commonly in jazz. The alt chord is a heavily altered dominant seventh chord, built on the alt scale that includes a flat ninth, sharp ninth, flat fifth, sharp fifth, and flat seventh. For example, C7alt is built from the scale C, Dmusic|flat, Dmusic|sharp, E, Gmusic|flat, Gmusic|sharp, Bmusic|flat. Enharmonically, this is almost the same as the scale for Gmusic|flat7, which is the tritone substitute of C7: Gmusic|flat (=Fmusic|sharp), Amusic|flat, Bmusic|flat, Cmusic|flat, Dmusic|flat, Emusic|flat (=Dmusic|sharp), Fmusic|flat (=E). The only difference is C, which is the sharp eleventh of the Gmusic|flat7 chord. Thus, the alt chord is equivalent to the tritone substitution with a sharp eleven alteration.

The Tritone substitution primarily implies a Lydian music|flat7, or Lydian Dominant Scale. In the Case of C7 to Bmaj7, the implied scale behind C7 would be C D E Fmusic|sharp G A Bmusic|flat. Because of this, the extensions of 9, music|sharp11 and 13 are all available while the music|sharp11 is where it shares with the Altered Scale.

Classical harmonic theory would notate the "substitute" as an augmented sixth chord, specifically the enharmonically equivalent German sixth, which serves as a substitute for the dominant of the dominant (V/V) (Satyendra 2005, p.55), sometimes referred to as "the German Augmented sixth on music|flat2".

Below is the original dominant-tonic progression, that progression with the tritone substitution, and the same progression with the substitution notated as an augmented sixth chord:

Tritone substitutions are a common technique (see ) in jazz and were first used by musicians such as Duke Ellington, Art Tatum, Coleman Hawkins, Roy Eldridge and Benny Goodman.

Tritone subtitutions are also known as substitute dominants, or Sub-V (Sub-five) chords.

ee also

*Coltrane changes

ources

*Stein, Deborah (2005). "Engaging Music: Essays in Music Analysis". New York: Oxford University Press. ISBN 0-19-517010-5.
*Satyendra, Ramon. "Analyzing the Unity within Contrast: Chick Corea's "Starlight". Cited in Stein (2005).