Tri-Tone Substitution - Introduction to Modern Jazz Lines #11-20

This week I'm beginning the next section of my Modern Jazz Line video series.  The goal of the first ten Modern Jazz Lines was to learn how to hear and improvise creatively over the ii-V-I progression.  Now, I'll admit ten jazz melodies played and sung in all twelve keys probably isn't enough to justify mastery. Please note however that these short ten video segments are meant as an introduction to each progression.  As with all subjects, student exploration and self study is essential to mastery.  I strongly encourage you to take on writing your own ii-V-I jazz melodies no matter how simple they may be.

The next section (#11-20) of the Modern Jazz Line series will cover the tri-tone substitution.  A "tri-sub" within a ii-V-I involves substituting a Dominant 7th chord a tri-tone away from the V7 chord.  The concept is explained simply in the video below.


Simply put, you can substitute a Dominant 7th chord a tri-tone away from the V chord (in a ii-V-I for example) because they share the same guide tones.

G7 = 3rd and 7th = B and F
Db7 (tri-sub) = 7th and 3rd = B and F!

If voiced correctly the two chords can and will function essential the same in a ii-V-I sequence.  If finding a tri-tone away from the V7 chord is hard at first just think a half-step below the ii chord.  I'll show you what I mean.

ii-V-I in C Major = Dm7-G7-CMaj7

with a tri-sub on the V7
ii-V-I in C Major = Dm7-Db7-CMaj7

Notice the root movement of the new progression.  Each note simply moves down in half-steps.  Feel free to use this method if it is easier for you to remember.