Tritone Substitution

Tritone Substitution in "Sentimental Mood"

One of the features of the chords in "Sentimental Mood" is the use of tritone substitution. This should be familiar to you, but let's recap:

Understanding Tritone Substitution

In a 2-5-1 progression, for instance:

• G minor 7
• C9
• F major

The middle chord, the dominant chord (V chord), can be substituted with a chord that is a tritone away (a flattened fifth away).

So instead of C, we're going to have G flat 7.

Listen to the Difference

• First Version: Original chords.
• Second Version: With G flat in the bass.

The only difference is the slight color on the dominant chord, which has G flat in the bass instead of C.

The Mechanics of Tritone Substitution

This works because in every dominant chord, you've got two notes that are a tritone apart. For C7, that's:

• E (the third)
• B flat (the seventh)

However, when I put G flat in the bass, it's now the seventh and third of G flat 7.

Magic!

When you invert a tritone, it's still a tritone. So, perhaps the easiest way to think of tritone substitutions is that a 2-5-1 becomes II flat 2 1. This means:

• The bass note goes down in semitones.

Important Note on Inversions

It's worth mentioning that if you play the flat 5 in the dominant chord (in G flat 7) like this, it has exactly the same notes as C7, B5.

They are inversions of each other, so it doesn't matter what inversion you play it in.

Example:

• C7 B
• G7 B

Additional Reference

You'll hear this tritone substitution at several points in the A section of "Sentimental Mood".

Also, remember that we had it in "Ornithology." Do you recall in the turnaround? Instead of:

• 2-5: 1625

It became 3 flat 3 2 flat 2 with the two tritone substitutions.

If you're still a bit vague about that, check out "Ornithology" and the lesson where I discuss that stuff!