Now that the seventh chords are understood we can talk about the ninth, eleventh and thirteenth chords as well as the altered dominants. As a jazz musician it is expected that you would use these chords to embellish or enhance the basic seventh chords shown in most jazz lead sheets.
The ninth chords are formed by adding one additional note to the seventh chords. Remember that the system of chord formation is based on thirds (tertian) so to form or spell the ninth chord we add an additional tone that is a third above the seventh of the chord. For example:
- C Major seventh = C E G B (1 3 5 7)
- C Major ninth = C E G B D (1 3 5 7 9)
Eleventh chords are formed by adding an additional tone that is a third above the ninth of the chord. For example:
- G eleventh = G B D F A C (1 3 5 7 9 11)
Thirteenth chords are formed by adding a tone a third above the eleventh:
- G thirteenth = G B D F A C E (1 3 5 7 9 11 13)
That is the limit on extensions because if we add another tone (fifteenth) we would be back to where we started (1 or the root of the chord).
The diatonic ninth chords in C Major are as follows:
- Chord I: C E G B D
- Chord ii: D F A C E
- Chord iii: E G B D F
- Chord IV: F A C E G
- Chord V: G B D F A
- Chord vi: A C E G B
- Chord vii: B D F A C
We will use the same system we used for the seventh chords to determine the quality of these ninth chords. The numbers show the number of half-steps that separate the chord tones.
- Chord I: C E G B D (4-3-4-3)
- Chord ii: D F A C E (3-4-3-4)
- Chord iii: E G B D F (3-4-3-3)
- Chord IV: F A C E G (4-3-4-3)
- Chord V: G B D F A (4-3-3-4)
- Chord vi: A C E G B (3-4-3-4)
- Chord vii: B D F A C (3-3-4-3)
Within these seven ninth chords are five unique structures. Of these five there are three that are commonly used. They are as follows:
- Major ninth = Major seventh chord plus major nine (Chords I and IV)
- Dominant ninth = Dominant seventh chord plus major nine (Chord V)
- minor ninth = minor seventh chord plus major nine (Chords ii and vi)
Notice how all the ninths added are major intervals. In other words the ninth that is added to the basic seventh chord is always the ninth degree of the major scale. This makes it convenient to then make a simple formula for ninth chords as we did with the seventh chords. We will use the major scale as reference and make three simple formulas as follows:
- Major ninth = 1 3 5 7 9
- Dominant ninth = 1 3 5 b7 9
- minor ninth = 1 b3 5 b7 9
You can see that if you understand the structure of the basic seventh chords creating a ninth chord is simply a matter of adding a major ninth. Think of the additional ninth as adding “color” to the sound without changing the function of the basic seventh chord in any way. Try adding these ninths to the basic seventh chords. Just remember to stay within the correct chord family. Major ninth chords embellish major seventh chords, Dominant ninth chords embellish Dominant seventh chords and minor ninths embellish minor seventh chords.
Eleventh chords basically come in two varieties; Dominant eleventh and minor eleventh. Adding the eleventh to the ninth chords in certain situations creates an unacceptable dissonance between the third of the chord and the added eleventh. This is most noticeable when the third of the chord is major. The eleventh sounds fine when added to the minor ninth chord but sounds terrible when added to the major ninth chord. When added to the Dominant ninth the third is usually omitted, so the eleventh sounds (and is often written) as a suspended fourth or sus4 for short. (The eleventh is a fourth plus an octave).
The two eleventh chords that we need to know are as follows:
- Dominant eleventh = 1 (3) 5 b7 9 11
- minor eleventh = 1 b3 5 b7 9 11
Try using these eleventh chords in place of the basic seventh chord. Again remember to use the Dominant eleventh to replace a Dominant seventh or ninth chord and use the minor eleventh to replace a minor seventh or ninth chord.
Thirteenth chords are again theoretically possible on all scale degrees but you will be relieved to know that there is only one type that is most common and that is the Dominant thirteenth. In a major key this is the chord built on scale degree five (V):
- Dominant thirteenth = 1 3 5 b7 9 (11) 13
(The eleventh is usually omitted for the same reason as stated earlier).
Try using this chord to replace the basic Dominant seventh, ninth or eleventh chord.
The final thing to understand is what are called altered dominants. Thankfully this only pertains to the Dominant seventh chord. Remember that this chord type is unique to scale degree five (V) in major keys and is the chord that has the strongest tendency to resolve to tonic.
Altered dominants consist of your basic dominant seventh chord with the possibility of including any or all of the extensions (9, 11, 13) and the addition of up to four more tones that are not diatonic within the major scale. These four new notes are the b5, #5, b9 and #9 major scale degrees. As we discussed earlier, these tones add considerable dissonance and tension to the dominant seventh chord and increase its tendency to want to resolve to tonic. So in the key of C major the V7 chord (G7) can include the following:
- G B D F A (C) E (Ab A# Db D#) and would be written as G13 (b9 #9 b5 #5)
Of course this is everything plus the kitchen sink and you usually don’t see all of this at once but it is possible.
Now we need to know the common voicings for these chords and some context as to how they are actually used. The following charts will hopefully show this. The first pdf shows two standard voicings for ninth, eleventh and thirteenth chords with roots on string six and string five.
The second pdf puts everything we have discussed so far into the context of a very common chord sequence known as a “turnaround” progression or iii-vi-ii-V-I in the key of C major and G Major. The vi chord (Am7) has been altered to form a secondary dominant (A7) or V/ii as it would be in common practice in order to achieve a greater variety of sound and chord choices. Along with altered dominants, tritone substitutions are also included. There are a few other chord types included that have yet to be discussed, i.e., Major with added sixth and ninth and some unusual enharmonic spellings where you sometimes see 7(#5) written as 7(b13). Also many of the voicings are rootless in order to include more of the extensions and alterations on the guitar. I have indicated where the root would be located with an open circle. When these voicings are understood you are well on your way to mastering the essentials of jazz harmony.