If you’ve ever wondered how top players make even simple progressions sound rich, modern, and inspiring, here’s the secret: they use ninth chords. And the best part? You can start using them right away—no advanced theory required.
Using what I’m about to share in this lesson, you can instantly upgrade basic triads and seventh chords into ninth chords in two shakes of a dog’s tail.
All I’m asking for is your undivided attention and that in the next four minutes or so, you discover the secret to an instant chord upgrade.
Let’s Define Ninth Chords
There are so many ways to define a ninth chord. In this lesson, we’ll be defining a ninth chord as follows:
A ninth chord is any chord, be it a triad or a seventh chord, that contains a ninth.
Think of a ninth chord as an enhanced version of the chords you already know (triads and seventh chords).
Take your basic triad or seventh chord, add the ninth of the scale, and you’ve created a fuller, more expressive sound.
What Is A Ninth?
When you take a closer look at these two chords:
C major triad:
C major (add ninth):
…it becomes really clear what the ninth is.
C E G = C major triad
C E G + D = C major (add ninth)
Even if you can’t hear the ninth (and maybe you can), I’m sure you can see that the ninth of the C major triad is “D”:
If C major triad + D = C major (add ninth), then D is the ninth of C
In the case of these two chords:
C major seventh:
C major ninth:
…we can also see that the difference between the C major seventh and the C major ninth chord is “D”:
C major seventh + D = C major ninth
That added note (D) is the ninth, and it makes a game-changing difference that adds openness, warmth: elevating chords from traditional to modern and giving them a more professional outlook.
You can’t find any gospel musician or contemporary keyboardist who is into smooth jazz, Neo-soul, R&B, etc., who doesn’t rely on ninths.
Why Is It Called A Ninth?
There are usually seven unique numbers in the scale degree numbering system (aka – “number system).
In the C major scale (C D E F G A B C):
C is 1 | D is 2 | E is 3 | F is 4 | G is 5 | A is 6 | B is 7
However, when you look at the extended number system, you have the following numbers:
C as the 8th tone (aka – “the octave”):
D as the 9th tone:
…and it goes all the way up to the 15th tone (the second octave):
C is 1 | D is 2 | E is 3 | F is 4 | G is 5 | A is 6 | B is 7 | C is 8 | D is 9 | E is 10 | F is 11 | G is 12 | A is 13 | B is 14 | C is 15
The extended number system is basically two octaves (side by side), numbered from the first to the fifteenth.
A lot of people know about the relationship between the first and eighth:
C is 1
C is 8
…known as the octave.
Beyond the 8th (aka – “octave”), that’s a duplicate of the 1st:
C is 1st and C is 8th
…there’s also the 9th that’s a duplicate of the 2nd tone:
D is 2nd and D is 9th
With that said, the ninth is simply the second tone of the major scale. It’s called the ninth because of its position in the extended number system.
We’ll talk more about this in class!
How To INSTANTLY Upgrade Triads And Seventh Chords
With the knowledge of what the ninth is, you can now upgrade triads and seventh chords by introducing the ninth, and this is done in two known ways: addition and extension.
The introduction of the ninth to a triad is described as addition while the introduction of the ninth to a seventh chord is described as extension.
Let’s take a look at the two known ways to form ninth chords: by addition and by extension.
[For Triads]: Ninth Chords By Addition
Super simple: take your major triad and add the second tone of the corresponding major scale.
If you’re given the Eb major triad:
…you can transform its sound by adding the second tone of the Eb major scale:
…which is F:
…and you’ll have an Eb major [add9] chord:
What’s the second tone of the B major scale:
Well, it’s C#:
Adding C# to the B major chord:
…produces the B major [add9] chord:
The introduction of the ninth to triads is called addition and produces added tone chords.
Check out a few add9 chords:
D major [add9]:
Ab major [add9]:
Gb major [add9]:
Bb major [add9]:
[For Seventh Chords]: Ninth Chords By Extension
If you already play seventh chords, here’s the next level:
C major seventh to C major ninth:
-
Cmaj7:
-
Cmaj9:
F minor seventh to F minor ninth:
-
Fmin7:
-
Fmin9:
G dominant seventh to G dominant ninth:
-
Gdom7:
-
Gdom9:
…and it’s the same process of introducing the second tone of the corresponding major scale:
However, the ninth is considered and extension and produces an extended chord.
What’s The Difference?
Both C(add 9) and Cmaj9 qualify as ninth chords:
C major [add9]:
C major ninth:
However, they belong to two different structural categories.
C major [add 9] is formed by adding the ninth to a triad. This results in an added-tone chord because no seventh is present.
C major ninth is formed by adding the ninth to a major seventh chord, which makes it an extended chord.
A chord is classified as an extended chord only when the ninth is introduced through extension of a seventh chord.
Introducing the ninth to a triad produces an added-tone structure, whereas introducing it to a seventh chord produces a true extension.
This distinction is essential for accurate analysis and for understanding how ninths function in harmonic contexts.
Final Words
Thanks for reading!
I’m sure that going forward, you can form added tone chords (from triads) and extended chords (from seventh chords) with the introduction of the ninth (the second tone of the scale).
The primary chords in C major:
C major:
F major:
G major:
…will sound a lot warmer when the ninth is introduced:
C major [add ninth]:
F major [add ninth]:
G major [add ninth]:
…and that is the goal of this lesson: to inspire you to upgrade your triads and seventh INSTANTLY with the introduction of the ninth.
Chuku Onyemachi
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