In this lesson you’ll learn the fundamentals of how and where to use 7b9 chords.

Say you’re playing a tune in a minor key. The dominant 7th chord usually looks like this: G7b9 or G7b13.

Here I’ll show you why that is, and later, I’ll show you how you can also use these 7b9 chords in major keys.

 

From whence do you hail?

 

Here’s the C Harmonic Minor scale: C D Eb F G Ab B C

The Dominant chord is built on the 5th degree of that scale. Start on the C and count up 5: CDEF – G.

Arranging the notes from G in 3rds [from G, count up 3 notes to B, then again 3 notes up to D, etc.] gives you this:

G B D F Ab C Eb

The first 4 notes – GBDF – make a G7 chord. This is our dominant 7th. Chord V.

The other three notes are Ab, C, and Eb. The Ab is the b9, The C is the 11th, The Eb is the b13.

If you have a 3rd already in the chord you normally don’t add the 4th/11th. So forget about the 11th.

On a G7, if you add extensions b9 and/or b13, that will give you the classic sound of the V chord in a minor key.

Here are some voicings:

G7b9

• 3 X 3 4 3 4 [use your thumb for the low G]
• X 10 9 10 9 10 [this one is like the B7 shape you first triumphed over but with the extra magic note added]

OK, now I want to show you how to use 7b9 chords in major key harmony.

 

From Minor to Major

 

First you have to know about Secondary Dominants.

Here are the chords in C major:

• C∆
• Dm7
• Em7
• F∆
• G7
• Am7
• Bm7b5

See the G7? That’s called the Primary Dominant. Chord V of the key we’re in. G7 to C. You’ve played this a billion times.

Now, Secondary Dominants are dominant 7th chords that go to all the other chords in the key of C.

So the second chord, Dm7, has its dominant chord which is A7.

The Em7’s dominant is B7

The F∆’s dominant is C7

The G7’s dominant is D7

The Am7’s dominant is E7

You wouldn’t in your right mind modulate TO a m7b5 chord. You might do that kind of thing if you were in a metal band and had no friends and were a bit stoned, but it’s not the kind of thing a Dragons’ Den watcher would do.

Chordal Charity

Now these secondary dominants are charitable chords.

They, by their authoritative dominance, offer a temporary home and some self worth to these errant diatonic children.

When you use a secondary dominant, it’s like you are bestowing more worth onto the target chord. It’s like an OBE, or a BAFTA. An affirmation of, ‘y’know, Am7, you’re OK. I like you’.

NOW then, the target chords can be split into two types: Major and Minor.

We have F∆ and G7 in the ‘major type’ chord camp; and Dm7, Em7, and Am7 in the ‘minor type’ camp.

When a dominant chord is going to one of the minor type chords, it takes on the characteristics of a classic minor key dominant, i.e., it’ll be the kind of dominant that has a b9 or a b13, or both.

THIS is the classic place where you can use 7b9 chords.

Ok, hope that gives you an idea of how to use 7b9 chords. There are other ways these chords can be used, and you can change the rules and do whatever you like, but I think it’s good to know the usual way of doing this, then you can notice the places where this ‘rule’ is broken.

Good luck!

Mike