As our exploration of jazz piano chords continues, it’s a good time to acknowledge that tritone substitution principle that is so often used by the pros. There are variations on this concept but the most popular one is what we will be looking at here.
Specifically, we are looking at tritone substitution as it applies to dominant 7th chords. Your perspective of jazz piano chords will expand as you become more and more familiar with this strategy. Let’s see how this works. We’ll start by looking at a G7 chord in its basic root position here:
G B D F
1 3 5 7
You’ll notice that we have highlighted the 3 and 7 of the chord in red. You’ll see why in a moment.
Let’s give attention to the root of this chord, the G. What is the note that exists a tritone away from G? (A tritone is an interval of three whole steps)
Whether you count three whole steps to the left or to the right, you arrive at Db, since a tritone divides an octave exactly in half. Now, let’s create another dominant 7th chord with Db as the root. This results, of course, in a Db7 chord:
Db F Ab Cb
1 3 5 7
Pay special attention to that highlighted 3 and 7 of this chord. What do you notice?
Look again at the G7 and then at this Db7. You’ll notice that the 3 and 7 of each chord are the same! That’s right. The 3 of the G7 chord is the 7 of the Db. Likewise, the 7 of the G7 is the 3 of the Db.
The 3 and 7 are the most important notes in a 7th chord. These are the notes that one could say define the chord. Since this is so, a very interesting possibility makes itself evident. Because the 3 and 7 of each of these chords coincides and these are the essential chord tones (more important than the 5), we can use one of these chords as a substitute for the other!
So, yes, if your tune calls for a G7 chord, you can consider playing a Db7 in its place… and vice versa. Essentially, the only thing that is changing is the root. This can quite a very tasteful option, depending on what the melody note is and the context of the chord itself. Also, your personal taste comes into play here as to which you prefer.
There is much more than can be said of this concept of tritone substitution but, for now, you are highly encouraged to become curious and explore your tunes by looking for those dominant 7th chords and considering substituting the dominant 7th chord whose root is a tritone away, as we have done above.
Your eyes and ears are about to open! Take your time with this and notice places where you prefer the substitute chord and where you prefer the original one. It’s your exercise of this privilege of choice that contributes to your own personal playing style!
PLAY WITH PASSION!