# Tri-Tone Substitution theory and practice [duplicate]

Can someone give me a practical explanation of the theory and practice of tri-tone substitution for jazz piano?

## marked as duplicate by jdjazz, Stinkfoot, Richard, MattPutnam, ttwMar 24 '18 at 13:54

The basic premise of the tritone substitution is that we take a chord (typically a major-minor seventh) that has a tritone in it and substitute the entire chord with another major-minor seventh chord that has the same tritone.

Let's begin in C major and imagine a V7 chord that progresses to I. Within the V7 chord (`G B D F`) is the tritone `B F`. This is shown at letter A below.

As it turns out, this tritone exists in another major-minor seventh chord, this one on D♭: `D♭ F A♭ C♭`. (Note that the `B F` tritone is now enharmonically spelled as `F C♭`.) This is shown at letter B above.

So basically, wherever you use a `G7` chord, you can substitute it with a `D♭7` chord, because the tritone stays the same in both harmonies. Note, too, that the roots of the chords—`G` and `D♭`—are a tritone apart.

Listen to a recording here.

We can take this one step further; let's stay in C major, but let's think about a secondary dominant to V. In other words, we're looking at V7/V, or `D7`. In this chord (`D F♯ A C`), the tritone is `F♯ C`; see C below. The tritone substitution of this harmony (again remembering that the roots are a tritone apart) will be `A♭7` (`A♭ C E♭ G♭`) with the enharmonically spelled tritone `C G♭`; this is shown at letter D.

If you've learned about the German augmented-sixth chord (`A♭ C E♭ F♯` in the key of C), you see here that it's enharmonically equivalent to the tritone sub of V7/V!