Jazz Building Blocks – Part 5

In this five part series we will be getting a foot into the doorway of jazz music. Jazz, and its theory has been something that I found really difficult to get into on my own so I wanted to write a series that would help give people the basics. This week we’ll be getting our heads around tritone substitutions:



Tritone substitution is one of those things that can be really confusing, but it’s really important to understand what it is, particularly when getting your head around a new piece. If a tritone substation is thrown in and you don’t know what it is then the piece can look like it doesn’t make any sense and has no logic. This might hurt your head a bit but it’s worth persevering! Here we go!


In short:


Tritone substitution occurs on dominant 7th chord. The root of the dominant 7th chord is replaced by the note an interval of a tritone away from the the root. Let’s look at this in more depth.


If we use G7 as an example:


1   3  5   7
G  B  D  F


In order to make a tritone substitution, we change the G for a C#. This is an interval of a tritone/#4/b5. On guitar, the change up will look like this:


  G7  tritone substitution (C#7#11)
e x            x
b 8            8
g 10          10
d 9             9
a 10           x
e x             9


Every other note stays the same, it’s just the bass note that is substituted by a note a tritone away from it. If it was an A7 then the A would be replaced by an Eb, if it was a B7 then the B would be replaced by an F.


Why a tritone and not any other interval?


Let’s look at G7 and C#7 (root notes a tritone apart) and see what they’ve got in common.


        1   3   5  7
G7 – G  F
          1    3   5    7
C#7 – C#  F  G#  B


The third of a G7 (B) is the same note as the seventh of a C#7 and the seventh of a G7 (F) is the same note as a third of a C#7. So we’ve got these interchangeable notes that together make up the third and the seventh of each G7 and C#7:


   G7     C#7
e x         x
b x         x
g 10      10
d 9         9
a 10       x
e x         9


Now, the third and seventh notes are more important than the fifth note of the chord. The fifth doesn’t generally alter the chord (apart from diminished chords) so if it’s not played then the listener will be fine without it. However, the third note of the chord will define whether its major or minor, while the seventh helps decide if the chord is a major 7, a minor 7 or a dominant 7. So, this is their relationship, let’s look at what it looks like in practice.


Why would anyone want to use a tritone substitution?


 Let’s refer back to our major ii-V-I progression:


   Dm7   G7    C∆
e x          x       x
b 10        8       8
g 10        10     9
d 10        9       9
a x          10     x
e 10        x       8


At present, we’ve got a nice ii-V-I progression with the baseline moving in fifths. Let’s replace the root of the G7 with a C#, a tritone away:


  Dm7  C#7#11    C∆
e x          x            x
b 10        8            8
g 10        10          9
d 10        9            9
a x          x            x
e 10        9            8


We’ve now got some chromatic movement in the bass. This gives a different feel and takes us away from the idea of the bass line constantly moving in fifths while still keeping the strength of the dominant 7th chord.


There are many ways of varying the tritone substitute with extensions. Each one will bring slightly different movement at the top of the chord. Here are few different types:
If you use a tritone substitute over a straight G7 then the C# chord will be a C#7#11. Don’t be scared by the chord names, it’s still only ever the root that changes:


 G7        C#7#11
e x            x
b 8            8
g 10          10
d 9             9
a 10           x
e x             9



If you use a tritone substitute over a G7♭9 then the C# chord will be a straight C#7.


  G7♭9      C#7
e x              x
b 9             9
g 10          10
d 9             9
a 10           x
e x             9


If you use a tritone substitute over a G9 then the C# chord will be a C#7♭13 (or C#7#5 if you’d rather say that).


  G9         C#7♭13
e x              x
b 10           10
g 10           10
d 9              9
a 10            x
e x              9


If you use a tritone substitute over a G7#9 then the C# chord will be a C#13.


  G7#9     C#13
e x              x
b 11           11
g 10           10
d 9              9
a 10            x
e x              9


Here’s how they sound when played as part of a ii-V-I progression. Have a play through and see which progressions you prefer. I’ll do them in different keys so you get a better feel for them:


   ii         (V)           I
  Bm7   B♭7#11   A∆
e x           x             x
b 7           5            5
g 7           7            6
d 7           6            6
a x           x             x
e 7           6            5


   ii         (V)         I
  Cm7     B7        B♭∆
e x           x          x
b 8           7          6
g 8           8          7
d 8           7          7
a x           x          x
e 8           7          6


    ii         (V)               I
  Gm7   G♭7♭13    F∆
e x           x                x
b 3           3               1
g 3           3               2
d 3           2               2
a x           x                x
e 3           2               1


    ii         (V)         I
  Am7    A♭13     G∆
e x           x           x
b 5           6          3
g 5           5          4
d 5           4          4
a x           x           x
e 5           4          3


   ii          (V)         I
  Dm11   C#7      C∆
e x           x           x
b 3           2          3
g 5           4          4
d 3           3          2
a 5           4          3
e x           x           x


   ii          (V)             I
  Gm11  G♭7♭9    F∆
e x            x              x
b 8            8             8
g 10          9             9
d 8            8             7
a 10          9             8
e x            x             x


    ii       (V)       I
  Em9   E♭9   D∆
e x         x         x
b 7         6        5
g 7         6        6
d 5         5        4
a 7         6        5
e x         x         x


     ii         (V)       I
  F#m9   F7#9   E∆
e x            x         x
b 9            9        9
g 9            8        8
d 7            7        9
a 9            8        7
e x            x         x





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