In jazz, can a tritone substitution take the place of a chord that is not a dominant chord?

Here's an example of what I'm talking about (I'm looking at the tune "Angel Eyes" Treble Clef Real Book):

Cm7 - Dm7b5 - G7#5 starts of the song to establish the key, but later there are cadences that use Cm7 - Ab7 - G7#5. So, my question is, is Ab7 here a tritone substitution for Dm7b5?

Dm7b5 = D, F, Ab, C; Ab7 = Ab, C, Eb, Gb; these chords are only two notes apart, with root notes a tritone apart, and both lead into the dominant (G7#5) as written in the tune. It seems to me to fit the idea of a tritone substitution quite well, but I just wanted to make sure I wasn't confusing myself...
Yeah that's right.

Since the two chords' roots are a tritone apart (Ab-D), and those seventh chords may be substituted for each other because they share the two pitches that form a tritone in each chord (the third and seventh.)

Tritone substitutions do not necessarily have to be on dominant chords, chords can be substituted as long as they share the same function.

In this case, both the Dm7b5 and Ab7 function as pre-dominant chords, as they resolve to the dominant chord (The G7)

Hope that helps.
Last edited by Jet Penguin at Jul 22, 2011,
Quote by Jet Penguin
Yeah that's right.

Since the two chords' roots are a tritone apart (Ab-D), and they both have the same function (in this case pre-dominant), this is a tritone substitution.

Those seventh chords may be substituted for each other because they share the two pitches that form a tritone in each chord (the third and seventh.)

Hope that helps.

Yes - thank you very much!
No problem. Yeah, as long as they have the same function a substitution is technically possible.