From “Blue Moon” to “I’ve Got Rhythm,” one of the most common progressions you find when playing jazz standards is the I–vi–ii–V. Known as the “one–six–two–five,” this progression appears in other song forms, but shows up a lot in the American Songbook.
In this lesson, you will learn about this progression as well as learn some great chord substitutions. By adding substitution chords, you can create more movement within a piece, give yourself variety, and add harmonic interest. One of the best things about using substitutions is that they can make any old song sound new again!
But before you can start changing up our progression, you will need to understand it. In Figure 1, I’ve written out our major scale in the key of C, with Arabic numbers instead of the conventional Roman, for ease of reading.
Now, we will give these letters qualities. These qualities tell you if the chord is a major or minor. In a major key, the rules for chord qualities are as shown in Figure 2.
However, most jazz chords tend to be four-note voicings, as opposed to the typical three notes (triads) listed in Fig 2. So, instead of our 1 chord being a regular C major (C E G), it could be Cmaj7 (C E G B) or C6 (C E G A) or even C 6/9 (C E A D). All of these are variations of a major chord, so any of them are valid replacements. The same goes for minor chords: D minor (D F A) could be swapped out for Dm7 (D F A C) Dm6 (D F A B), Dm9 (D F A C E), etc.
Two chord qualities that will change from what is listed above are the 5 and 7 chord. The 5 chord is the most important change and becomes a dominant seventh chord, which builds on a major chord by adding the flatted seventh. In this instance, the G chord will become a G7, and contain the notes G, B, D, and F. Notice that all four of those notes exist in the key of C. The 7 or half-diminished seventh chord is a special case and not part of this lesson’s chord progression, so we will have to study it some other time.
Figure 3 shows the qualities we’ll work with, for now.
Now, applying 1, 6, 2, and 5 to our progression in the key of C, we get Example 1. Take some time to practice playing through this chord progression, giving each chord two beats. If you create a loop of this progression, or record yourself playing it over and over, you’ll be able to sing all of the verses to “(I Love You) For Sentimental Reasons.” However, after a while, you may find yourself bored with the same old chords. This is where substitutions come into play!
The first substitution, shown in Example 2, replaces the 1 chord (Cmaj7) with the 3 chord (Em7). Compare the Cmaj7 and the Em7 and notice there is only a one note difference. Try playing the 1–6–2–5 progression followed by the 3–6–2–5. The difference is slight, but this little variation creates a harmonically pleasing change of pace.
This brings us to our second variation, Example 3. Many of you may have already played this progression without realizing it. Instead of playing the Am7, we substitute a passing chord to get us to the Dm7 instead. This passing chord is chromatic, meaning that the root of the chord is a half-step away. In Example 3, the open C in our 1 chord leads to a C# then to the root of the Dm7 chord. The C#dim7 passing chord adds tension to the progression. (Note that in the ukulele vernacular, this chord is commonly referred to simply as C#dim, despite its inclusion of the flatted seventh, Bb/A, which technically makes it a diminished seventh chord.) This gives your ear the sensation that you are headed somewhere.
For our final variation, we are going to break the rules! The 6 chord is typically minor, but you can sometimes get away with changing the quality, like in Example 4. In this substitution, I want to create chromatic movement and play the same pattern twice. Notice that I’m using a second-position Em7 chord. In order to create chromatic movement on my A string, I need to change my Am7 to an A7. The Em7 and Dm7 chords are based on the same shape, but starting on different frets, and A7 and G7 also look very similar. In essence, you are playing the same pattern of chords as you move down the neck of the instrument. This creates a deliberate movement in your progression.
Now let’s go back to that earlier exercise of singing “For Sentimental Reasons.” Play through all of the progressions we’ve covered thus far and sing the verses. You’ll enjoy how nicely the variations sit together.
This is just an introduction to chord substitutions. By using natural extensions (odd-numbered notes beyond the seventh) and other chord positions, you can create movement within these variations. Dust off some of your old favorites and give these a try. You’ll be surprised how much fun you’ll have. Happy strumming!
[Update: this version corrects a mistake in the print edition. The doubly flatted seventh of a C#dim7 chord is incorrectly identified as Bbb/A. That note is, in fact, Bb.]