Working with the Coltrane Matrix is an effective way to gain insights into harmonic relationships and tonal commonalities. In this etude I’ve organized each measure of the Matrix into a minor and augmented triad. If you look at the example above you’ll see in the first measure an E minor triad followed by an Eb augmented triad. Sonically, the “Eb” in this measure functions enharmonically as a “D#”, because it implies the triad descending by a half step to its major seventh. So the net tonal organization of this measure is that it is in the key of E minor (this min/aug triad pair is diatonic in E minor). The “B” natural happens to work very well over the Eb7 chord, adding a bit of tension.
The pattern continues, transposed accordingly. The second measure is directly stating the C minor tonality (and in hindsight, is actually implying the C minor tonality starting on the Eb7 chord; hence, the Eb 7 chord straddles both the C minor and E minor tonalities); the third measure state the G# minor tonality (the tonality being implied starting on the B7 chord). Notice the relationship between these three keys: descending major 3ds. The line finishes with the original melodic statement an octave lower, continuing the minor color. Utilizing these common tonalities in each measure is a good way to sound less “vertical” (strongly marking the tonality of each chord) and instead sound a bit more “horizontal” (as if playing “through” the chords rather than “over” them). Plus it creates a tonal color and sequence rarely heard over these changes. (It’s a way to sound a little less “Giant Steps-y”)
So much can be discovered by spending time with this chord sequence! If you’d like to delve more deeply into finding some more unconventional approaches to playing over these chords (and discover how doing so can really open up what you do on more typical ii-V7 type progressions), please consider my e-b00k, The Coltrane Matrix: 40 Unique Melodic Ideas in All 12 Keys. Click on the link below to download the free, pdf version of this etude.