Chord Progressions: Tritone Substitution

Tritone Substitution (TS) occurs when you replace the original chord in a chord progression with another chord of the same quality whose root is a tritone away. For example...

TS works especially well with dominant 7 chords and is used in many standard Jazz chord progressions, as you will soon discover.


Tritone Substitution applied to the V7 chord

Here is the basic ii7-V7-IM7 in the key of C...

tritone substitution

tritone substitution

 

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Now we are going to replace the G7 chord with its tritone substitute. The tritone substitute for G7 is Db7 (the chord whose root is a tritone away from and shares the same quality with G7)...

tritone substitution

Special Note about the Roman Numeral Analysis: "bII7" is probably more accurately described as "TS/V7" in theoretical terms, but why quibble? This is where the limitations of theory start to get in the way of the concrete experience of real music.

tritone substitution

Notice that...

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What does tritone substitution accomplish?

TS expands the harmonic and melodic possibilites of music in at least three ways:

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Why does tritone substitution work?

TS works well for at least three reasons:

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A functional view of tritone substitution

It is critically important to realize that, although the substitute chord sounds different than the original chord, it still performs the same harmonic function as the original chord. The Db7 chord, like the G7 chord, functions as a tension chord that wants to resolve back to the key center C.

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Tritone Substitution applied to secondary dominants

In addition to substitution for a V7 chord, one can also extend the notion of TS to the following applications:

Secondary Dominants, an example

Original progression:
CM7 || C7|| FM7
I7 || V7-V || IVM7
TS progression:
CM7 || Gb7 || FM7
I7 || TS/V7/IV || IVM7

Note: Gb7 = TS of C7

Listen to the original and TS version side-by-side:

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Secondary ii7-V7 Cells, an example

Original progression:
Dm7 G7 || CM7
ii7 V7 || IM7
TS progression:
Abm7 Db7 || CM7
TS/(ii7-V7) || IM7

Note: Abm7-Db7 is the ii7-V7 TS for Dm7-G7

Listen to the original and TS version side-by-side:

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Extended Secondary Dominants, an example

This occurs quite often in Jazz Blues turnarounds.

Original progression:
C7 || A7 || D7 || G7
I7 || V7/ii || V7/V || V7
TS progression:
C7 || Eb7 || Ab7 || Db7
TS/V7/ii || TS/V7/V|| TS/V7

Note: Eb7 is the TS for A7, Ab7 is the TS for D7, and Db7 is the TS for G7.

Listen to the original and TS version side-by-side:

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Of course, it is possible to mix and match all of the ideas above in delicious combinations.

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Jazz Standards that employ tritone substitution

Well You Needn't (Monk)

The A section is Jazz Blues vamp that altnerates between I7 and a TS/V7 in the key of F:

F7
Gb7
I7
TS/V7

 

All Blues (Davis)

A 12-bar Blues a TS/V7/V in the key of G:

G7
%
%
%
C7
%
G7
%
D7#9
Eb7#9 D7#9
G7
%
I7
%
%
%
IV7
%
I7
%
V7
TS/V7/V V7
I7
%

 

Girl From Ipanema (Jobim)

The 8-bar A section includes a straighforward TS/V7 in the key of F:

FM7
%
G7
%
Gm7
Gb7
FM7
Gb7
IM7
%
V7/V
%
ii7
TS/V7
IM7
TS/V7

 

Satin Doll (Ellington)

The 8-bar A section includes a secondary ii7-V7 cells TS/(ii7-V7) in the key of C:

Dm7 G7
%
Em7 A7
%
Am7b5 D7
Abm7b5 Db7
CM7
(A7)
ii7-V7
%
(ii7-V7)/ii
%
(ii7-V7)/V
TS/(ii7-V7)
IM7
V7/ii