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22. 9th chords

Using extended chords is a great way to add colour to your chord progression. We already talked about triads and 7th chords in previous episodes, and now have come the time to speak about 9th chords. What are the different types of 9th chords and how to actually use them.

BEATS & BOBS 

as you probably already know, to build a chord, you basically take the notes of the scale you want to use, start with the note you want to build a chord from, that's the note which will give the chord its name, and then follow the notes of the scale, keeping one note every two.

If you keep 3 notes, you have a triad, which is made if a tonic, a 3rd and a 5th. I'll leave a link to the episode about triads in the description. 

If you keep 4 notes, you have a 7th chord, which is made of a tonic, a 3rd, a 5th and a 7th. I'll leave a link to the episode about 7th chords in the description. 

And if you keep 5 notes, then you have 9th chord, which is made of a tonic, a 3rd, a 5th, a 7th and a 9th. Then the nature of this 9th chords depends on the intervals separating each note. That's what we'll see now.

There are many types of 9th chords, so we'll start from the most commonly used and finish with the more rare ones.

Just before we begin, I'd like to make 3 notes

1- One thing to keep in mind is that the more extension notes you add above a triad, the more colour the chord has. But also the more tension you add, so generally these 7th and 9th notes needs to be resolved in one way or another.

2 - This 9th note is actually the same note than the 2nd but an octave higher. So it can introduce friction with the tonic and the 3rd as these notes are very close. To attenuate this friction it is often advised to keep the 9th an octave higher, so it'd sound smoother. But there's no particular rule for that, so you can do as you want

3 - when we don't play the 7th of the chord, so we have only a triad with a 9th, we call that "add9". And generally this 9th is a major 9th.
So we can have for example a Cmadd9 which is a C minor chord plus a major 9th
Or we can have for example a C add9 which is a C major chord with a major 9th

You'll see in a minute how you can use those as they are only variations of other 9th chords I have on my list

DOMINANT 9

So the first type of 9th chord is the dominant 9th, which is simply noted "9". It is made of a major triad, with a minor 7th, so that's a dominant 7th chord, to which we add a major 9th. 

So for a C chord that would be C, the major third E, the perfect fifth G, the minor 7th Bb and the major 9th D.
This type of chord is often used as a dominant chord, on the Vth degree of you tonality, and that would resolve well on a Ist degree for instance.
To avoid the friction introduced by the 9th, the ... is sometimes omited

In C major for example, the Vth degree would be G, so the progression could be G dominant 9 to C major

In A minor, a V to I progression would make E dominant 9 to A minor

7b9

Now to add more tension in that 9th chord, you could alter it by lowering the 9th by a semitone. So the chord would be made of the same dominant 7th chord, with a minor 9th added. This type of chord would be noted 7b9. 

So for a C chord it would be made of the root note C, the major third E, the perfect fifth G, the minor 7th Bb and the minor 9th Db.
And it would be used and resolved it the exact same way than a dominant 9th chord.

So in C major, that would make G7b9 to C major

And in Am that would make E7b9 to A minor

7#9

You could also alter the dominated 9th chord the other way around, by moving the 9th up a semitone instead of down. That will make a 7#9 chord, which is built with a dominant 7th chord to which we add an augmented 9th. This chord is also known as the "hendrix" chord as it was made popular by Jimi hendrix. We saw it in the episode about the blues scale. 

So for a C chord it would be made of the root note C, the major third E, the perfect fifth G, the minor 7th Bb and the augmented 9th D#.
Again it is used and resolved just like a dominant 9th chord.

So in C major that would make G7#9 to C major

And in A minor it would make E7#9 to A minor 

To sum it up you can use a dominant 7th chord on a Vth degree to which you add either a major 9th, a minor 9th or an augmented 9th, depending on the colour you like. Works well both a major and a minor tonality

MAJOR 9

Then you have major 9th chord which is made of a major triad, with a major 7th and a more 9th. So that's a major 7th chord with a major 9th added.

On a C chord that would make the root note C, the major third E, the perfect fifth G, the major 7th B and the major ninth D

This is a type of chord you can use on the Ist degree and on a IVth degree in a major tonality, but you can also use it on a IIIrd degree or on a VIth degree of a minor tonality. Using the major 8th chord on these degrees would work better as it would use notes that are already in the tonality you're using.

So in the tonality of C major that would mean using a F major 9th for the IVth degree, or a C major 9th for the Ist degree.

As an example we can try a chord progression that goes from I to IV then IV to I. That'd be: CM9 to F major, then FM9 to C major

Or in A minor,  we can use a CM9 for the IIIrd degree or a FM9 as the VIth degree. For example we could make this chord progression
A minor - FM9 - CM9 - E7 - Am

MINOR 9

the chord we commonly name minor 9th actually contains a major 9th. The minor 9th chord is made of a minor triad, with minor 7th and a major 9th. So it's like a minor 7th chord with a major 9th added.

So on a C chord that would be the root note C, the minor third Eb, the perfect 5th G, the minor 7th Bb and the major 9th D

That's a type of chord you can find in a major tonality on the IInd degree and the VIth degree, as building a 9th chord on these degrees using only the notes of the major scale would make a minor 9th chord. This type of chord seems more efficient on the IInd degree before a Vth degree chord.  So that would prepare a nice II - V - I chord progression, if you want to resolve that progression totally.

And in a minor tonality this type of chord can be found on the Ist and the IVth degrees

So in the tonality of C major, the VIth and the IInd would be Am and Dm so we could make the chord progression: Am9 - Dm9 - G7 - CM

And in the tonality of A minor for instance, the IVth and the Ist degrees would also be Dm and Am, which can go well together: Dm9 - Am9

m7m9

now we could have a minor triad with a minor 7th and a minor 9th. This type of chord would generally be noted as m7m9.

For a C chord for example that would be the root note C, the minor 3rd Eb, the perfect fifth G, the minor 7th Bb and the minor 9th Db

This is a types of chord you can find in a major tonality on the IIIrd degree, and in a minor tonality on the Vth degree. But it is less common in a minor tonality as for a Vth degree chord, a dominant 9th chord is often preferred.

So in the tonality of C major for example, the IIIrd degree would be E minor. So we could make that a Em7m9 chord:
Em7m9 - F - C

°\7m9

Then we can have a 9th chord build with a diminished triad, with a minor 7th and a minor 9th. So it's like a half diminished 7th chord, to which we add a minor 9th. I like to call this type of chord half diminished 9th, but it is often called simply diminished 9th, which I think can be a bit confusing.
So to avoid confusion, we can call it half diminished 7th minor 9th, with this crossed circle that means half diminished. Or could call it m7m9b5, to say that's like a minor 7th chord, with a minor 8th and a fifth that is lowered by a semitone. But I find this a little long.

Anyways, on a C chord that would be the root note C, the minor 3rd Eb, the diminished 5th Gb, the minor 7th Bb and the minor 9th Db.

That's a type of chord you could find in a major tonality on the VIIth degree, and in a minor tonality in the IInd degree.
 But it is more used in minor tonalities as the VIIth degree could be analysed as a Vth degree without root note, the tension it brings to the chord progression is very similar.

So let's see how it sounds in a minor tonality, on the IInd degree.
In A minor, the second degree would be B, so this B half diminished 9th would be made of the notes B, D, F, A and C.

B°\7m9 - E7 - Am

EXOTIC 9TH CHORDS

so that a lot of different types of 9th chords already, and a lot of options to chose from. But almost all these chords can already be found within a major or a minor tonality, as they only use notes from the major or the minor scale.

Now we're going to see some types of 9th chords that can be a bit trickier to use, as they are altered versions of the previous ones, and they use notes that are outside of the major or minor scale. So more options to explore, but maybe a bit trickier to use.

°7m9

You can have what I like to call a fully diminished 9th chord. It is made of a diminished triad, with a diminished 7th and a minor 9th. So that's like a diminished 7th chord to which we add add lino 9th.

So for a C chord that would be the root note C, the minor 3rd Eb, the diminished 5th Gb, the diminished 7th Bbb, which is the same note than A, and the minor 9th Db.

To avoid confusion with the previous °\7m9 chord that is sometimes just called diminished 9th, we can call this one °7m9.

This is add very dissonant chord add voir it contains 2 intervals of a tritone, and an interval of a minor 2.

This is a type of chord that is sometimes used in a minor tonality, on the VIIth degree.

So in the tonality of Am, that would be a G°7m9.
G°7m9 - Am

+9

The augmented 9th chord is made of an augmented triad, with a major 7th and and a augmented 9th. That can be noted +9 or aug9

So for a C+9 chord that would be the root note C, the major 3rd E, the augmented 5th G#, the major 7th B and the augmented 9th D#.

That's a type of chord that is more often used in a minor tonality on the VIth degree

So in A major, the VIth degree would be F, and we could have this chord progression:
F+9 - Am

+7M9 (on III)

You could also have a augmented triad with a major 7th and a major 9th, and that could be noted +7M9

So for a C+7M9 chord that could make the root note C, the major 3rd E, the augmented 5th G#, the major 7th B and the major 9th D.

This is a type of chord that you could use on the IIIrd degree in a minor tonality

So this C+7M9 could be the IIIrd degree in the tonality of A minor

C+7M9 - Am

mM7M9 (on I)

And finally you could have a minor triad with a major 7th and a major 9th. So that like a m9 chord we saw earlier but with a major 7th instead of a minor one. And that can noted mM7M9.

So for a CmM7M9 chord that would be the root note C, the minor 3rd Eb, the perfect 5th G, the major 7th B and the major 9th D.

That's a chord that can be a substitute for the Ist degree in a minor tonality.

So in A minor, the A minor chord could replaced by a AmM7M9 chord at some point

AmM7M9 - E9 - Am9

CONCLUSION 

So that 11 different types of 9th chord to experiment with in your compositions. That's a lot of options. 
But remember that your chords don't have to be all 9th chord. 9th chord are great to add a bit of colour, but it may not always be the colour you want for each chord. So as always,  trust your ears.

One way to voice these 9th chord that can be good is to have a bunch of notes clustered in the middle, with some notes a bit apart in the bass and some other in the higher note. So you'd have the colour of the 9th chord, but with a defined bass and a defined melody.

So that's all for me today. If you liked this video or found it useful, click the like button. If you want to see more, check out my playlist music theory in 5 minutes, and subscribe to the channel if you like what you see.
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Anyways thanks for watching, and I'll see you next time!

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