An extended chord is a seventh chord to which an extension note — the ninth, 11th or 13th degree of the major scale — is added.
A ninth chord — as the name suggests — is a seventh chord to which the ninth scale degree is added.
This post will cover how to construct ninth chords and provide examples for each type of chord.
It will also provide common fingerings for each chord, along with instruction on how to play them on a guitar with any root note.
Identifying the Extension Notes
Extension notes are notes that go beyond a major scale’s octave.
To find the extension notes, we need to extend a major scale beyond its root note’s octave (the scale’s eighth note) and assign degree (or scale step) numbers to the additional notes.
An extended C major scale with its scale degrees labeled is shown in fig.1.
Fig.1
The extension notes in a major scale are identified as follows:
- The ninth degree of a major scale is the same note as the second degree, an octave higher. In a C major scale, the ninth degree is D (fig.1, highlighted in blue).
- The 11th degree of a major scale is the same note as the fourth degree, an octave higher. In a C major scale, the 11th degree is F (fig.1, highlighted in purple).
- The 13th degree of a major scale is the same note as the sixth degree, an octave higher. In a C major scale, the 13th degree is A (fig.1, highlighted in green).
The 10th,12thand 14th degrees of a major scale are the same notes as the third, fifth and seventh degrees, respectively. They are already included in a seventh chord and are not considered extensions.
Major Ninth Chords
If we add the ninth scale degree to a major seventh chord, it becomes a major ninth chord.
The chord formula for a major ninth chord is: 1, 3, 5, 7, 9.
A major ninth chord contains the first, third, fifth, seventh and ninth degrees of the major scale with the same root note.
For example, a Cmaj9 chord contains the notes C, E, G, B, and D — the first, third, fifth, seventh and ninth notes in a C major scale (fig.2a).
Dominant Ninth Chords
If we add the ninth scale degree to a dominant seventh chord, it becomes a dominant ninth chord.
The chord formula for a dominant ninth chord is: 1, 3, 5, b7, 9.
A dominant ninth chord contains the first, third, fifth, flatted seventh and ninth degrees of the major scale with the same root note.
A C9 chord contains the notes C, E, G, Bb and D — the first, third, fifth, flatted seventh and ninth notes in a C major scale (fig.2b).
Minor Ninth Chords
If we add the ninth scale degree to a minor seventh chord, it becomes a minor ninth chord.
The chord formula for a minor ninth chord is: 1, b3, 5, b7, 9.
A minor ninth chord contains the first, flatted third, fifth, flatted seventh and ninth degrees of the major scale with the same root note.
A Cm9 chord contains the notes C, Eb, G, Bb and D — the first, flatted third, fifth, flatted seventh and ninth notes in a C major scale (fig.2c).
Fig.2
Summary of Ninth Chord Formulas
The ninth chord formulas covered in this post are summarized below:
- Major ninth: 1, 3, 5, 7, 9.
- Dominant ninth: 1, 3, 5, b7, 9.
- Minor ninth: 1, b3, 5, b7, 9.
Ninth Chords Based on All 12 Root Notes
The ninth chords based on all 12 root notes are shown in fig.3.
Fig.3
Omitted Notes
All of the notes in an extended chord formula don’t necessarily have to be included in any particular chord voicing. Some notes are less important than others and can be omitted.
The important notes that should always be included in an extended chord voicing are the chord’s third and seventh degrees and the highest extension note (the ninth scale degree for ninth chords).
Root notes, the fifth scale degree and other extension notes are routinely left out of extended chord voicings on a guitar.
Ninth Chords on a Guitar
Major Ninth Chords
A common fingering for a major ninth chord is shown in fig.4.
Fig.4
This fingering will allow you to play a major ninth chord with any root note:
- To play a Cmaj9, place your second finger on the C on the fifth string, third fret (fig.5a).
- To play an Emaj9, place your second finger on the E on the fifth string, seventh fret (fig.5b).
Fig.5
Dominant Ninth Chords
A common fingering for a dominant ninth chord is shown in fig.6.
Fig.6
This fingering will allow you to play a dominant ninth chord with any root note:
- To play a C9, place your second finger on the C on the fifth string, third fret (fig.7a).
- To play an E9, place your second finger on the E on the fifth string, seventh fret (fig.7b).
Fig.7
Minor Ninth Chords
A common fingering for a minor ninth chord is shown in fig.8.
Fig.8
This fingering will allow you to play a minor ninth chord with any root note:
- To play a Cm9, place your second finger on the C on the sixth string, eighth fret (fig.9a).
- To play an Em9, place your second finger on the E on the sixth string, 12th fret (fig.9b).
Fig.9
Chord Quality and Harmonic Function
The extension notes add color, texture and complexity to the seventh chords to which they are added. They don’t change the chord’s quality or harmonic function.
For example, the chords C7 and C9 are both dominant chords and both primarily function as the V chord in the key of F major.
Application
Ninth chords are commonly substituted for seventh chords, especially in blues and jazz chord progressions.
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