Chord theory 4 - Extended chords

On the previous pages, we have covered a lot of theory, and looked closely at:

• triads
• seventh chords
• added note chords

Now we are going to complete the picture by looking at:

• extended chords

Extended chords

As with triads and seventh chords, extended chords are based on the idea of stacking thirds.

This gives us the following notes, or chord factors:

• root
• 3rd
• 5th
• 7th
• 9
• 11
• 13

The following diagram shows these chord factors on the piano keyboard, with the root C.

Any chord with the root, 3rd and 7th is a 7th chord.

If the chord - in addition - contains any one of the 9, 11 or 13, then it is an extended chord.

The chord can include the 5th, but it is the least important note in the chord. It doesn't add much to the chord and you leave it out.

There are three basic extended chords, with the following chord factors:

The 3rd may be a minor third or a major third, which would make the chord a minor or major chord.

We can make the chord more complex by more than one of the 9, 11 and 13.

Before looking at individual chords, we need one final definition, which is an altered chord.

Armed with this toolbox, we can now start building extended chords.

Ninth chords

The 9th chord contains the root, 3rd, 5th, 7th and 9.

Fundamentally, we can make any combination:

• minor or major 3rd
• with or without the 5th
• dominant or major 7th
• 9, ♭9 or ♯9

Let's look at some of these in more detail. On the piano we will use the root C. On the guitar we will look at the shape of movable chords using the root B on string 6, the root E on string 5 and root A on string 4.

For simplicity we will leave out the 5th.

9 chord

The basic 9 chord is a dominant 7th chord plus the 9.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• dominant 7th
• 9

Minor 9 chord

The minor 9 chord is a minor 7 chord plus the 9.
Leaving out the 5th, we have the notes:

• root
• minor 3rd
• dominant 7th
• 9

Major 9 chord

The major 9 chord is a major 7 chord plus the 9.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• major 7th
• 9

Flat 9 chord

The flat 9 is a so called altered chord, because it uses the flat 9 instead of the 9.

The flat 9 chord is a dominant 7 chord plus the ♭9.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• dominant 7th
• flat 9

Sharp 9 chord

The sharp 9 is a so called altered chord, because it uses the sharp 9 instead of the 9.

The sharp 9 chord is a dominant 7 chord plus the ♯9.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• dominant 7th
• sharp 9

Note:
In music theory, the notes in a scale always use a sequence of letters in alphabetical order. For example, if the root is A, then the second note is B, the third is E and so on.

This rule has some consequences, which might not seem intuitive:

• The 9 in the key of B is C♯. In music theory, the ♯9 is therefore C♯♯, denoted as C𝄪.
  This is the same note as D.
• The 9 in the key of E is F♯. In music theory, the ♯9 is therefore F♯♯, denoted as F𝄪.
  This is the same note as G.
• The 9 in the key of A is B. In music theory, the ♯9 is therefore B♯.
  This is the same note as C.

If you are not a student of music theory, then you probably think this is plain weird.

9 suspended 4th chord

The 9 suspended 4th or 9sus4 chord is a 7th suspended 4th chord plus the 9.
Leaving out the 5th, we have the notes:

• root
• 4th
• dominant 7th
• 9

Eleventh chords

In principle, you can build an 11th chord as a dominant 7th chord plus the 11, with

• root
• major 3rd
• optionally the 5th
• dominant 7th
• 11

For example, a C11 chord would look like this on the piano keyboard:

In this form, the 3rd (E) and the 11 (F) create a dissonant clash, so that the chord is never really used.

One option, is to leave out the 3rd to make a chord with only the chord factors 1, 5, 7 and 11.

In this form, the 11 takes on the role of a suspended 4th, so rather than being C11 this effectively becomes a C7sus4 chord.

So for practical purposes, the 11th chord does not exist.

However, two forms do exist, which avoid the dissonant clash between the 3rd and 11:

• the minor 11 chord
• the sharp 11 chord

Note:
There is no ♭11 chord, because the a flat 11 would be the same as the major third.

Let's look at these two chords in more detail. On the piano we will use the root C. On the guitar we will look at the shape of movable chords using the root B on string 6, the root E on string 5 and root A on string 4.

For simplicity we will leave out the 5th.

Including the 9

An 11th chord can also include the 9. This is optional, at the discresion of the player.

Very unusually, the chord symbol might specify (no9) - for example Cm11(no9) - to indicate that the 9 should not be included.

Minor 11 chord

The minor 11 chord is a minor 7th chord plus the 11.
Leaving out the 5th, we have the notes:

• root
• minor 3rd
• dominant 7th
• 11

In all three cases, we have made the guitar chord more playable, by swapping the order of the 3rd and the 11.

In particualar in the Bm11 shape, with the root on string 6, you can see that the notes in this voicing are all separated by the same interval, which is a fourth. This makes it a special kind of chord which can be formed by stacking fourths.

Sharp 11 chord

The sharp 11 is a so called altered chord, because it uses the sharp 11 instead of the 11.

The sharp 11 chord is a dominant 7th chord plus the sharp 11.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• dominant 7th
• sharp 11

Thirteenth chords

An 13th chord contains the root, 3rd, 5th, 7th and 13.

Fundamentally, we can make any combination:

• minor or major 3rd
• with or without the 5th
• dominant or major 7th
• 13 or ♭13

Note:
There is no ♯13 chord, because the a sharp 13 would be the same as the dominant 7th.

We have already discussed 6th chords, and the possible confusion with 13th chords, but I am going to repeat it.
The 6th and the 13 are the same note on the scale, so what is the difference between the chords?

Now let's look at some 13th chords in more detail. On the piano we will use the root C. On the guitar we will look at the shape of movable chords using the root B on string 6, the root E on string 5 and root A on string 4.

For simplicity we will leave out the 5th.

Including the 9 and 11

A 13th chord can also include the 9. This is optional, at the discresion of the player.

Very unusually, the chord symbol might specify (no9) - for example C13(no9) - to indicate that the 9 should not be included.

It would be unusual to include the 11, because of the dissonant clash with the 3rd. The 11 could be included in the minor 13th chord.

13 chord

The basic 13 chord is a dominant 7th chord plus the 13.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• dominant 7th
• 13

Minor 13 chord

The minor 13 chord is a minor 7th chord plus the 13.
Leaving out the 5th, we have the notes:

• root
• minor 3rd
• dominant 7th
• 13

Major 13 chord

The major 13 chord is a major 7th chord plus the 13.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• major 7th
• 13

Flat 13 chord

The flat 13 is a so called altered chord, because it uses the flat 13 instead of the 13.

The flat 13 chord is a dominant 7th chord plus the flat 13.
Leaving out the 5th, we have the notes:

• root
• major 3rd
• dominant 7th
• flat 13

13 suspended 4th chord

The 13 suspended 4th or 13sus4 chord is a 7th suspenede 4th chord plus the 13.
Leaving out the 5th, we have the notes:

• root
• 4th
• dominant 7th
• 13

Altered chords

We have already met some altered chords. These were the seventh chords

• 7th flat 5
• 7th sharp 5

and the extended chords:

• flat 9 chord
• sharp 9 chord
• sharp 11 chord
• flat 13 chord

Here's a reminder of the definition:

We can create more altered chords by:

• adding a flat 5 or a sharp 5 to any extended chord
• adding a flat 9 or sharp 9 to an 11th or 13th chord
• adding a sharp 11 to a 13th chord
• any combination of the above

Chord notation

The notation of an altered chord is to write the basic chord followed by the altered notes.

For example C13♭9 means a C13 chord plus a flat 9.

The altered notes may be written in brackets, for example C13(♭9). This is often used if there are multiple altered notes, for example C7(♭9♯11).

The basic chord cannot be based on an altered note. For example, if we start with a C9 chord and flatten the 9, it cannot be written as C♭9, but must be written as C7♭9. (C♭9 would be a 9th chord with the root C♭).

Altered 5th chords

The 5th is usually the least important note in a chord. The 5th simply sounds too like the root, and doesn't add much colour to the chord.

So in most chords, you can play the 5th, or leave it out, as you like. In our discussion of extended chords, we almost never included the 5th.

If a chord includes a flat 5 or sharp 5, then it becomes a different chord.

Altered fifths are notated with ♭5 or ♯5, unless the chord has a well-established symbol such as ^o for diminished, ^ø for half-diminished seventh, or + for augmented chords.

An altered 5 can be applied to any 7th chord and to any extended chord.

Altered extention notes

So far, we have looked at extended chords with only one extension note, the 9, 11 or 13.

However, an extension chord contain any combination of extension notes, with the following conventions:

• the chord is named according to the highest (unaltered) extension note
• additional extension notes are only included in the chord symbol, if they are altered notes

This means:

• a 13th chord may include the 9 or the 11
  (but the 11 would be avoided if the chord contains a major 3rd)
• an 11th chord may include the 9

Altered extention notes should be specified in the chord symbol

An example of using an altered chord

There are very many altered chords, most of which sound quite strange and are rarely used.

Where they are used, the altered note is most likely a passing note in a voice.

A good example is the chord sequence Dm7 → G7♭5 → CΔ7, which is a version of the ii-V-I progression, that we discussed in relation to the minor 7th chord.

In this sequence the lowest note (or voice) steps down chromatically from D to D♭ to C.
The G7♭5 is used to mainly to create this chromatic sequence, rather than for its own sake.