Relative Substitution
Another common method of substitution involves relative major and minor chords. Once again, this is because there are notes common to both chords. Cmaj7 contains the notes C, E, G and B, while Am7 contains the notes A, C, E and G. As you can see, the notes C, E and G are in both chords.
This is why these chords work so well as substitutes for each other. The other note in the Am7 chord (A) implies a 13th when played over Cmaj7, while the B note in the Cmaj7 implies a 9th when played over Am7. This process works for all relative major and minor chords. The following example demonstrates these substitutions as arpeggios and then an improvised line. Work through this substitution on all 12 notes of the chromatic scale.
If you are playing with other musicians who understand chord substitution, you may decide to alter the parts played by other members of the group (e.g. bass, keyboards and guitar) as well as the soloist. Then the substitution becomes the standard progression and completely changes the character of the progression itself. This process is particularly useful for making Jazz arrangements of simple popular songs. Shown below is a 1 4 5 progression in the key of C major, along with an alternative version written underneath involving relative minors which may be used as substitutions for the I and V chords. Notice that all the chords have also been extended to 7ths in the second version.
If you analyze the notes of any major 6th chord, you will notice that it is exactly the same as a first inversion of it’s relative minor: Therefore, these chords may be freely substituted for one another whenever they occur. In the following example, the saxophone plays a repeated riff using the notes C E G and A while the bass note alternates between C and A. Listen to the CD to hear the effect this creates.
