substitute

This Issue: Superimposition

the title is ambiguous, so here’s what we’re doing. From our ‘vanilla’ chord progression of Em-C-G-D, we’re going to keep just the bass notes and then replace the rest of each chord with a different major or minor triad. instead of the first E minor, we might have a D major or B minor triad over an E bass note. to narrow the choice, we’ll just use the diatonic chords in the key of E minor.

DiaTonic chords are the ones built from a single scale. That gives us Em, F#dim, G, Am, Bm, C and D. Even using just these triads and our E-C-G-D bassline, that’s quite a few permutations! But are we going beyond substitution? Is the first chord now G major? The original bass notes maintain the shape of the progression. Instead of hearing a G chord, we hear the notes of the G triad as they relate to an E root… as extensions, suspensions or whatever. When placed over a different bass note, a triad no longer has its usual ‘meaning’.

Here’s a case in point. We no longer hear the G note as the root in a G major triad; it’s now the minor 3rd of an E chord. By superimposing a G major triad over E, we’ve created Em7.

someHow this one does feel more like a marriage of disparate elements. Perhaps it’s because none of the expected C major (or Cmaj7) notes are in the D triad. In isolation, this would be very ‘C Lydian’. It’s a C root with 6th, 9th and #11th.

Here’s another example where the original function of the upper triad is lost, as the sound of the resulting chord is defined by the bass.A B minor triad over a G bass note gives us Gmaj7.

THe inverse of the second chord, and this is a very common sound; it can also be interpreted as D9sus4. These are just four permutations within one key, but you could be much more liberal. Try bolting triads and bass notes together and see what happens!