The harmony that’s in a piece of music is often the determining factor of how good it sounds. The lead sheet or chord chart is quite often the roadmap to that harmony. But it doesn’t end there if you understand the concept of chord substitutions.
Chord substitution is the art of utilizing one chord in place of another. The purpose is often to enrich the harmony of a piece of music and/or to accommodate a melody note that may not work with the harmony given.
Chord substitution can range from simple to advanced. It’s best to understand them at the most basic level and then proceed from there. We’ll start with simple triads and use a lead sheet with Keyshots to illustrate.
If you’re familiar with lead sheets, you know that they consist of a one note melody line with chord symbols to guide a musician through a song. This is unlike traditional sheet music in which it’s common to have a comprehensive arrangement. You can however, create chord substitutions from virtually any written piece of contemporary music.
I also want to emphasize there are no rules for the number of chords which you can substitute in a song. Chord substitution is a matter of taste and the desire to redefine it with a change in harmony.
1 Using Common Tones
The first method of chord substitution is to use common tones which are notes that are common in the chord given as well as the substitute.
Triads are the bread and butter of harmony. You’ll find them in any popular song. There are times when they get the job done and others when a more satisfying chord is desired.
Let’s say we have a simple melody with basic triads for the harmony.
If we wish to substitute any given chord using this common tone strategy, we only need to ask ourselves: What other chord will this melody note fit into?
Here we have C as a melody note that is harmonized by the C Major triad.
So what other chord will C melody note fit into?
Here’s another option for C
We also have minor triad options for C.
There are also options for suspended chords although they’re not as commonly used for substitutions as Major and minor chords.
Beyond triads and suspended chords, this concept gets real interesting when you apply it to extended chords. This opens up your options exponentially
2 Relative Minor/Major Chord Substitutions
Another strategy is to substitute a Major or minor chord with its relative counterpart. In the case of a Major chord, you could use the relative minor chord. As you’ll see, this substitution makes use of common tones also.
If you have a C Major chord, you can substitute it with A minor which is the relative minor of C.
To find the relative minor chord of any Major chord, simply find the 6th tone of the Major key and play a minor triad based on it.
You can also find the 6th tone by moving down a minor 3rd interval from the root.
In the case of a minor chord, you could use the relative Major chord.
Of course, if you have an A minor chord, you can substitute it with C Major which is the relative Major. The opposite of the example we just looked at.
3 Dominant to minor 7 Substitutions (a fourth down)
With any dominant chord, you can substitute with a minor 7th chord that’s based on the fourth interval below it.
With an F7 chord, you can substitute with a C minor 7 chord.
To find the fourth interval, just count four scale tones down from the root of the 7th chord.
4 Tritone Substitutions
A tritone is defined as a musical interval that spans three adjacent whole tones.
Another way to think of a tritone is a diminished 5th in the context of a chord.
The tritone substitution makes use of this interval by utilizing a chord based on the diminished 5th of the chord given.
To substitute a G7 chord with the tritone, find the tritone of G by moving up three whole tones from G.
Now that we can see the tritone of G is D flat, we can use the D flat 7 chord as our tritone substitution.
5 Secondary Dominants
The dominant chord is based on the fifth tone in a Major key of music.
The dominant chord contains the flatted 7th. In this example, F.
The dominant chord naturally resolves to the tonic chord. In the key of C, this is G7 to C.
A secondary dominant chord is based on the 5th of the 5 chord which is D for our example.
In the case of G7 it would be the D7 chord.
In the context of a chord substitution, you could play the D7 just before G7 in the chord progression.
The purpose of the secondary dominant chord is to resolve to a chord other than the tonic chord. For example, if you’re in the key of C Major, you may use an A7 as a dominant chord to resolve to the two chord which is Dm7.
6 Altered Chords
When you raise or lower diatonic tones in a chord by a half step, you alter them. This adds non-diatonic tones and creates altered chords.
The diminished 5th (aka flat 5) chord is a very common chord substitution. For example, a C7 chord can be substituted with C7 flat 5 by simply lowering the 5th.
You can also alter a minor 7 chord such as C minor 7 with the flat 5th.
For a more jazzy sounding altered chord, you could also raise the 9th and 5th for a sharp 9 sharp 5 chord. Take the following example of F sharp 9 sharp 5.
It’s common to use this chord as a substitute for the V chord in a progression moving to a I chord.
7 Minor 7 to 11 (a fifth down)
With any minor 7th chord, you can substitute with an 11th chord that’s based on the fifth interval below it.
For example, for C a minor 7 chord, you can substitute with F11.
To find the fifth interval, just count five scale tones down from the root of the 7th chord.
Beyond these strategies to create chord substitutions, there is a key concept to make note of. If the substituting chord contains two or more tones that exist in the original chord, it’s a possibility for a substitute.
I use the word possibility because even though they share common tones, it’s not a foolproof way to create a substitute chord. Your ear will be the final judge for an acceptable substitute.
Apply these concepts to create chord substitutions in your own music and remember that they can be applied to any chord. The key is to experiment and document your discoveries and the ones you consider to be your favorites.
Until next time, Go Play.
Greg Lee
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