Advanced Reharmonization – Part 2 of 2

In Part 1 of our article on advanced reharmonization we discussed two tips for understanding how to get started with chord substitution. Here in Part 2 we’ll go further with some study of advanced reharmonization using Gershwin’s “Summertime” by discussing some common chord progressions as well as the idea of tritone substitutions.

Advanced Reharmonization Tip #3: Using ii-V-I Progressions

Let’s go back to the original first 4 measures of Gershwin’s “Summertime,” and take a look at measure 3. The original harmony for this measure is an A minor 7 chord. But of course, we’re going to use some advanced reharmonization ideas. What other chords could we use to harmonize the ‘A’ on the downbeat of measure 3? Let’s consider options if the ‘A’ were the root, 3rd, 5th, or 7th of a chord.

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  1. if ‘A’ is the root, chord could be: A major, A minor, A dominant, A diminished, A minor 7 flat 5;
  2. if ‘A’ is the 3rd, chord could be: F major, F dominant, F# minor, F# diminished, F# minor 7 flat 5;
  3. if ‘A’ is the 5th, chord could be: D major, D minor, D dominant, Eb diminished, Eb minor 7 flat 5;
  4. if ‘A’ is the 7th, chord could be: Bb major, B minor, B dominant, B minor 7 flat 5, C# diminished.

After trying out many of the options above the one I liked most was the F major 7th chord at the start of measure 3.

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It’s easy to tell why this chord works so well – there are a lot of common tones between F major 7 and A minor 7. Both chords use A, C, and E as chord tones, so that explains a little bit as to why the sound of the F major 7 chord blends so well with the melody. But how can we move the harmony from A minor 7 to F major 7 using the advanced reharmonization technique of the ii-V-I progression?

As you probably know by now, ii-V-I progressions are some of the strongest and most common chord progressions in music and are used extensively in jazz. So we’ll work backwards in our effort to move the progression from A minor to F major by asking the following questions:

  1. What dominant 7th chord can we use to bring us to F major 7? Answer = C dominant 7, because C is a 5th away from F.
  2. And now that we have a V-I progression (C7 to F), what minor 7 chord would we insert ahead of C7 in order to complete the ii-V-I progression? Answer = G minor 7.

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Advanced Reharmonization Tip #4: Tritone Substitutions

Now that we have our ii-V-I progression in place, we can also consider how to move from A minor to G minor. We could insert a D7 chord in measure 1. Why D7? Because D7 is the V of G minor, so we’re creating another V-I progression. But we could also substitute the D7 chord with its tritone substitution – Ab7. Tritone substitutions can be used anytime we see a dominant chord. Basically, we can substitute a dominant chord with another dominant chord a tritone away (a tritone is an interval of a diminished 5th or augmented 4th). D7 and Ab7 are both dominant chords and are a tritone away and therefore can be substituted for one another. We could also use this idea of tritone substitution on our C7 chord by substituting and F#7 chord in its place.

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