9. Chord Progression Tricks

MAJOR/MINOR SUBSTITUTIONS:
A cool trick for spicing up chord progressions is to use minor substitutions for major chords, or major subs for minor chords.

Think of the seven diatonic triads of the major scale (MAJ/min/min/MAJ/MAJ/min/dim). These positions are labeled (I/ii/iii/IV/V/vi/vii°).

So say I have a chord progression that goes ( I - IV - ii - V ). In C major that would be ( C - F - Dm - G ).

If you want to flip the tonality of a progression, or part of a progression, you can replace a "I" with a "vi", a "IV" with a "ii" or a "V" with a "iii". This works because these pairs of chords have two notes in common and the third note is a step apart.

In our progression, C (CEG) can easily be traded for Am (ACE), F (FAC) can switch with Dm (DFA), and G (GBD) can switch with Em (EGB). It's a cool way flip the mood of a song.

If we had a minor scale the triads would still be 1-7, but labeled (i/ii°/III/iv/v/VI/VII) because of the chord qualities. You would swap the "i" and "III", "iv" and "VI", and "v" and "VII".

Go back to the post on triads and look at the fretboard charts. If you compare the diagrams you can start to see why using inversions makes chord changes smoother. (Look how close Em 1st inversion is to C 2nd inversion.) This is the same basic idea behind using major/minor chord substitutions. (C root inversion is almost Am 1st inversion.)

BORROWED CHORDS:
Diatonic chords are fantastic and harmonious, but sometimes throwing something slightly out of key in the mix does wonders. Borrowed chords are chords that are diatonic to a scale parallel to the one you’re using. You could, for example, throw in a diatonic chord from C minor in a C major piece. This opens up a lot of different tonal colors. Since harmonic and melodic minors have different patterns of intervals, they have diatonic chords that do not exist in the modes of the major scale.

The diatonic seventh chords of the C harmonic minor are (Cm/M7, D∅, Eb+M7, Fm7, G7, AbMaj7, B°7). For C melodic minor, they’re (Cm/M7, Dm7, Eb+M7, F7, G7, A∅, B∅). Augmented, full-diminished, and minor-major seventh chords don’t occur diatonically in the modes of the major scale at all, but they sound awesome.

An exercise I've found very useful recently is determining the scale of a simple chord progression, then looking up all the diatonic and borrowable triads and seventh chords. Then I'll look up the easiest to play position on a chord generator and just fuck around moving between them, seeing what blends and what doesn't. You can sound stupid-jazzy in no time.