Watch the (D) Tri-Tone Subs online guitar lesson by TrueFire from Play Jazz Guitar 4: Rhythm Approaches
(D) Tri-Tone Subs - The bored bass player chord is a video guitar lesson presented by Fareed Haque and is sourced from Jazz Comping Survival Guide.
In this section we will use the principle of tri-tone substitutions to create some new more modern comping sounds. A tri-tone sub is a simple concept also with far reaching applications. First off what is a tri-tone? Tri-tone is a fancy name for an #4/b5 interval. Here is the idea: A C7 has guide tones E and Bb. But the Dominant 7th built a tritone away also has the same guide tones: Tri-tone away from C7 is Gb7. Gb7 has guide tones Bb and E ( actually officially Fb, but whatever). So since the guide tones are the same the important notes are the same! Since C7 usually wants to go to F. Gb7 going to F is not that much of a stretch. Just imagine that bored bass player trying to stay awake playing C, c, c, c, c, c, c, c, c, c, c, then on down to F. Eventually that bass player is going to throw in a chromatic note down to F and "Voila!" Gb to F, with guitar player banjo player or piano player stomping on C7 creates tha fancy tritone sub, a Gb7 chord.