Jazz Guitar Chord Theory (part 3)

In part 2 we had a look at how seventh chords are constructed. In part 3 we'll focus our attention on tensions.

Tensions are notes that are part of a chord, but are not chord tones (1 3 5 7).

Let's have a look again at the C major scale :

C Major Scale	C    D    E    F    G    A   B
	1    2    3    4    5    6    7

If we construct a chord on C, we get a Cmaj7 :

C    E    G    B

1    3   5    7

There are 3 notes left in the major scale that are not chord tones : 2, 4 and 6.
If we add these tones to the chord, they become tensions.
Most of the time we play tensions an octave higher then the chord tones because else they might get in the way of the chord tones (the chord would sound 'muddy' most of the time).  That's also the way they are notated : 2 becomes 9 (2+7(one octave)=9), 4 becomes 11 and 6 becomes 13.

So if we add the 2 to Cmaj7 we get Cmaj9

C    E    G    B    D

1    3   5    7    9

The two other notes that are left, the 4 and 6, are special cases in combination with a major chord.

First of all here is something we call avoid notes : notes that are a half tone above a chord tone.  Avoid notes sound disharmonic so they are almost never used.
If we have a look at the 4 of the C major scale we notice that it is a half step above the e, what is the 3rd of Cmaj7.  So the 4 (f) is an avoid note for Cmaj7.
A solution for this is to raise the 4 a half tone: f becomes f# and is no longer an avoid note and the basic scale is no longer C major, but C Lydian (see jazz guitar modes).  This chord would be called Cmaj7(#11).

The 6 is also a special case in combination with major chords.  Most of the times when we add a 6 to a major chord, the 7 is omitted and there is no octave added to the 6.   This is because the 6 and 7 might get in each other's way.
So if we add the 6 to C major we get a C6 :

C    E    G    A

1    3   5    6

The same goes for 6 in combination with a minor chord : the 7 is omitted.
If we add the 6 to Dm7 we get Dm6 (Look out : the 6 is no longer A because the root of the chord changed to D.   The six is now B (D E F G A B C) :

D    F    A    B

1    b3   5    6

The 4 is not an avoid note in combination with minor chords because it is two half tones above the b3 and not one half.
So we can safely add the 4 to Dm7 and we get Dm11 :

D    F    A     C      G

1    b3   5    b7    11

The 4 is also a special case in combination with dominant chords.
When a 4 is added to a dominant chord, the 3 is omitted.  Chords like these are called sus4 chords.
Chords like these often function as a delay for a dominant chord.
Sus4 chords often come with a 9 on the guitar :

G    C     D      F    A

1    4     5     b7    9

There's also something called altered tensions (b9, #9, b5, b13).  This topic is covered later in another lesson.

The different chord types and their tensions :

Chord Type	Added Note	Symbol
Major	2	Cmaj9
	4 #4	/ Cmaj7#11	avoid note. #11 comes out of lydian scale
	6	C6	omitted 7
Minor	2	Cm9
	4	Cm11
	6	Cm6	omitted 7
Dominant	2 b2 #2	C9 C7(b9) C7#9	b2 and #2 come out of the altered scale
	4	C7sus4
	6 b6	C13 C7(b13)	b6 comes out of altered scale

Part 4 of jazz guitar chord theory : a quick way to construct chords + some examples  

  Return to guitar chord theory part 2