Q&A: Tri-tone Subs in a 2-5-1

By HSJF AdminApril 27th, 2011Groove with Berklee Faculty

Question from K.C. in New Jersey:

My question is about using subs, specifically tri-tone substitutions, in a ii-V-I turn-around. I play guitar and am talking about creating harmonically interesting ideas during comping.

 

Answered by Ken Zambello

Thanks for your question! Ah yes, tri-tone subs and the 2-5-1.

First a bit of theory. When a dominant 7th chord is “functioning”, that is, moving to its 1 chord in a progression, it can be substituted with a dominant chord a tri-tone away from its root.

In the key of C a typical standard 2-5-1 would be:

D-7 / G7 / Cmaj 7

The tri-tone substitution in our example would replace G7 with the dominant chord a tri-tone away from its root resulting in Db7.

The notes that make up the Db7 chord are actually available as chord tones on G7 or as tensions on an altered G7 which is why the Db7 works as a substitution for the original 5 chord — they share the same notes:

So, let’s look at the chord tone relationships between our original 5 chord, G7, and our tri-tone substitution, Db7. Working downwards:

The b7th of Db7 = Cb (B) which is the 3rd of the G7 chord
The 5th of Db7 = Ab which is the b9th of the G7alt chord
The 3rd of Db7 = F which is the b7 of G7 chord
The Root of Db7 = Db which is the #11 of G7alt chord

The result is that you are creating a nice harmonic contrast or movement, mixing things up harmonically a little bit, but the melody remains the same. Try it out!