Jazz Building Blocks – Part 4

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 looking at chord extensions:



This week we’re going to be looking at extension chords. In the ‘Theory Maze’ document we went as far as seventh chords, but it can be confusing when you start seeing chords like D7#5♭9! At first glance, these chords can look scary, but they are named and constructed very logically. So, the aim of today’s lesson is to give you the tools to unravel these chords and get more familiar with them, rather than more intimidated!
First off, let’s tackle some of the higher numbers like, 9ths, 11ths and 13ths. We’re in C, and we’re going to be doing 2 octaves:


1   2  3   4  5  6   7  8   9  10 11   12  13  14   15
C  D  E  F  G  A  B  C  D  E   F   G   A    B    C


We can immediately forget about some of these numbers:


Forget 8th: It’s just the root note played an octave above so we always refer to it as a root.
Forget 10th: It’s just a third played an octave above so we always refer to it as a third.
Forget 12th: It’s just a fifth played an octave above so we always refer to it as a fifth.
Forget 14th: It’s just a seventh played an octave above so we always refer to it as a seventh.
Forget 15th: It’s just the root played two octaves above so we always refer to it as a root.


You need to remember the numbers of the first octave, but after that you only really need 9ths, 11ths and 13ths. As we’ve seen from previous blogs, we generally build up our chord by playing every other note. For example, a C∆ chord is built up like this:


1       3       5       7
C  D  G  A  B  C


We start on C, then skip the D to get to E, then skip the F to get to G, then skip the A to land on B. Therefore creating a C∆ with the notes C, E, G and B.
If we apply this rule further along then can extend C∆ to C∆9, C∆11 and C∆13 (Note: if you simply say C9, C11, C13 without the major 7 sign, ∆, then you are implying that the chord is a dominant 9, 11 or 13.)


C∆9 – C, E, G, B, D
1       3       5       7       9
G  A  B  C  D


C∆11 – C, E, G, B, D, F
1       3       5       7       9      11
G  A  E  F


C∆13 – C, E, G, B, D, F, A
1       3       5       7       9      11     13
G  A  E  F  A


Now, if you look at C∆13 you’ll realise that we’re using every note of the C major scale. If we squash this down into one octave then it will look like this:


1    2/9    3   4/11   5   6/13   7     1
C     D     E     F     G     A     B     C


C = 1 or the root note
D = 2nd or 9th
E = 3rd
F = 4th or 11th
G = 5th
A = 6th or 13th
B = 7th
Also, note that a major 13th, minor 13th and dominant 13th all share the same 9th, 11th, and 13th. It’s still only the third and 7th that determines whether the chord is major, minor or dominant.


When do I know whether to call it 2nd or a 9th, 4th or an 11th etc?

Well, if we had a ‘sus2′ chord then we would have notes 1, 2 and 5. The 3rd has been replaced by the 2nd. Same with a ‘sus4′ chord, where you’ve got notes 1, 4 and 5. In contrast, a major 9 chord would have notes 1, 3, 5 and 7 with the 9th on top. Or an ‘add9’ chord would the original triad, 1, 3 and 5 with the 9th added (no 7th). This is the same with ‘add11’ chords.
6ths are slightly different. You wouldn’t hear the phrase ‘add13’ often because it’s usually the same as a 6th chord. So, a 6th chord (e.g. C major 6th/C6 or C minor 6th/Cm6) would have the notes 1, 3, 5 and 6. A 13th chord would have the whole lot, notes 1, 3, 5, 7, 9, 11 and 13.


Right, we’ve got a grasp on standard 9th, 11th and 13th chords, let’s look at how to alter them. This is actually fairly simple, it just takes a bit of working out.


Let’s take a C9 chord:
1   3   5    7      9
C  E   G   B♭  D
(the 7th in a dominant chord is always a flat 7/minor 7, hence why it’s a B♭ not a B natural. That’s what makes it a dominant seventh: a major triad with a flattened 7th on top)
So if we saw the chord symbol C7#9 or C7♭9 then this is what would happen.
The first four notes make up the C7, so they stay the same:
1   3   5    7
C  E   G   B♭
However, the 9th either sharpens/is raised by a semitone (if it’s a #9) or is flattened/falls by a semitone (if it’s a♭9)


1   3   5    7      #9
C  E   G   B♭   D#
1   3   5    7    ♭9
C  E   G   B♭   D♭


Here’s what it looks like on guitar:


   C9    C7#9   C7♭9
e  x        x          x
b  3        4          2
g  3        3          3
d  2        2          2
a  3        3          3
e  x        x          x
If we had a C7#5 or a C7♭5 then every note note would stay the same apart from the 5th:


1   3   5    7
C  E   G   B♭


1   3   #5    7
C  E   G#   B♭


1   3  ♭5     7
C  E   G♭   B♭


This is what it looks like on guitar:


    C7     C7#5   C7♭5
e   x         x          x
b   8         9          7
g   9         9          9
d   8         8          8
a   x         x          x
e   8         8          8


It seems complex but there are only a limited number of alterations you can make. They are:




That’s it. Any other alterations just make up chords that already exist. If you flatten the root then it’s just a major 7, sharpen it and it’s a flat 9, so nothing new there. If you flattened a major 3rd it just becomes a minor third, if you sharpen it then it becomes a natural fourth. If you flatten a major seventh it becomes a dominant/minor seventh, sharpen it and you get the octave. If you flatten an eleventh then it becomes a major third. If you sharpen a thirteenth then it becomes a dominant seventh.
So try and get your head around those extensions. Practice them in different keys. Get a Jazz Real Book and go through a load of Jazz Standards to see where these extensions regularly come up. After the ‘Jazz Building Blocks’ series I’ll be doing more lessons on guitar chords, which will eventually get to some of the shapes of these extensions.







Leave a Comment

You must be logged in to post a comment.