Minor 3rd Chord Substitutions

The most common chord change in all of music is:

V-I

In the key of C, this is G7 to C major. This chord progression goes from a very tense chord to one of complete resolution. You’ll find this sequence all the way back to Beethoven, Hayden, Bach, and more.

You’ve probably played it a million times at this point and you’re ready for something new and fresh. How do composers write songs that sound DIFFERENT that don’t involve only using V-I’s? Or, if you want to use it, how can you add a bit more spice to it?

You can do so by using chords that are a minor 3rd apart. You will find this technique used by the great impressionist composers Ravel and Debussy. The famous movie composers John Williams and Jerry Goldsmith used it as well.

Here I show what it sounds like on the 5-string banjo. You can follow along on your guitar or any chordal instrument.

Substituting chords a minor 3rd apart

For the visually inclined, this means chords that are three frets apart from one another.

What’s three frets (or steps) away from G? That is Bb (One note at a time: G-G#-A-Bb)

Let’s try this progression:

Bb7 to C major

What is three frets away from Bb7? That would be Db7

So try this now:

Db7 to C major

By the way, this substitution has a special name; it’s called a TRITONE SUBSTITUTION. More on that later.

Let’s keep going. Three up from Db7 is E7. Our final chord substituion:

E7 to C major

I wanted to give you the answers first so you could try it and experience it for yourself. At this point, you are probably wondering WHY does this work? Let me show you:

Here are the notes in each of the chords. Please understand that G# and Ab are equivalents on our instrument.

If you look at G7 and Bb7, you will notice they both contain the pair of notes D-F

If you look at Bb7 and Db7, they both contain the pair of notes F-Ab

Db and E7 both contain B-Ab

Lastly, E7 and G both contain the notes B-D

In other words, there are TWO common tones between each of these chords.  In fact, it doesn’t even matter if you go in order like I did-you can pick G7 and Db7.  Once again, TWO common notes.  Every chord in that group of four chords has two common pairs related to one another.  Try it for yourself.

Common Chord Substitution Rule

Any chords that share two or more notes can be substituted for one another.

Now that you understand it a bit more, let’s really explore this idea and run it for all it is worth!

Using Chord Substitutions to add harmonic acceleration

Suppose we have four bars that go G7-G7-C-C. How can we take what we learned above and apply it. Look over the following.

We start by substituting Bb7 for G7 in the second measure. By the time we are done, we have a chord change every two beats instead of every two measures. We have some serious HARMONIC ACCELERATION here. Later on we will explore even overlaying each of these chords corresponding scale for improvisational purposes.

I think you get the point-The possibilities are endless. At the same time, please consider and be respectful of the type of music you are playing or writing. I primarily use these in my jazz playing or composing. Occasionally, I’ll add two substitutions to a bluegrass song, but this is much more rare.

Be sure to check out my prior ii-V-I exercises if you missed it.

Lastly, If you want to go further with similar ideas or need any more direct attention, please feel free to contact me about:

Online Jazz Guitar Lessons or banjo lessons.