When I was younger and first getting into learning about harmony I was always fascinated in particular by certain jazz pianists and their ability to string long complex chord sequences together, drifting in and out of original key with ease. This is what I became to understand as chord substitution, and is done to harmonic variety and interest to a piece.

The original melody was still embedded in what they were doing, but its was constantly being re-contextualised, pushed and pulled out of focus. Pianists like Bill Evans, McCoy Tyner, Mal Waldron, George Shearing, Kenny Barron, Chick Corea and latterly Brad Mehldau were masters of this craft in my eyes. What they were really doing was actually quite structured, quite literally swapping the chords or “changes” of the original tune with logical alternatives.

Mal Waldron.

The substitutions may have a quality and degree of function in common with the original chord, and often only differs by one or two notes, or they may be far more off the wall, flirting with other keys and modes temporarily, then with deft skill brought back to the home tonal centre.

This article is meant to serve as a basic introduction to substitutions. I’m really just covering the theory behind it, using them tastefully is an art in itself.

The most important things to remember is taste, context, and reference (to the melody). It’s no good throwing obnoxious heavily extended altered chords at a sensitive ballad or going on some modal odyssey during Fly me to the Moon (or perhaps there is? Sure someone can make it work).

So, let’s start at the beginning.

Consonance and Dissonance

Nearly all european and western music conforms to some basic rules. You may seek to break them. You may think what you do is different and you’re oh-so avant garde and post modern, but the chances are you music still relies on the tried and tested constructs of consonance and dissonance, or to put it differently; tension and relief.

Western harmony is derived from the harmonic series (more on this at a later date) which comes from the natural physical phenomena of vibrating strings at different lengths, and whilst I’m not here to illustrate that the point I am trying to make is that although music is very subjective – some constants should be understood.

The V – I movement (chord 5 to chord 1 in a major or minor scale) is the strongest in western harmony. In the key of C major this would be G to C, or G7 to C. There are other ways of finishing chord sequences using different cadences, but this movement has a gravitational pull.

McCoy Tyner.

If you play a melody and stop three quarters of the way in, you will naturally fill in the gaps with your mind – our ear seeks to resolve melodies, harmonies and bass lines. Of course, you don’t have to finish your piece of the tonic, and there are various ways to get from skin the proverbial cat, but knowing about tonal centres and keys can help when exploring chord substitutions.

For example, if you’re in the key of C, we might be able to dabble in various related keys (F major, G major, A minor) we might be able to sideslip into more arbitrary-sounding keys (Db major, B major, Gb major) but we need to return back to our goal key in order to put a bow on our progression, and the best re-harmonizers know this.

Common Substitutions

One of the easiest ways to quickly start modifying your chord changes is by swapping two chords that share similar notes. Staying with our example key of C major, you’ll find there’s a plethora of chords that share two notes. If you’re unfamiliar with chord naming conventions, please read this.

Chord Name Symbol Notes Substitutions
C major 7
C∆7
C E G B
E-7, A-7
D minor 7
D-7
D F A C
F∆7, Bø
E minor 7
E-7
E G B D
G7, C∆7
F major 7
F∆7
F A C E
A-7, D-7
G dominant 7
G7
G B D F
Bø, E-7
A minor 7
A-7
A C E G
C∆7, F∆7
B minor 7 flat 5
B D F A
D-7, G7

The net result is you can really interchange most of these chords freely without compromising the harmonic direction or movement of a piece.

Of course it’s not that sample and you have to be aware of the melody. If the downbeat of the melody is a C, then A minor would work fine, but an E minor not so much (E minor has no C in it).

However this is only really the beginning. We can further extend these chords with richer voicings using 9s, 11s, 13s and altered extensions. We can even swap major chords for minor and vice versa.

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