Harmony

Last Updated: 14 Aug 2021

This post is a collection of ideas all about musical harmony, especially in Jazz. Though they come in all sorts of flavors and styles, many chord progressions are built on the idea of tension and release. We play dissonant chords to “push” the melody towards a nice resolution, which usually is the tonic chord (also known as the home chord).

Two-Five-One

This is the bread and butter of jazz harmony. It starts with the minor 7th on the second, then the major 7th on the 5th, and finally resolves back the root. Everything from here on out basically either builds on, or modifies this fundamental underlying sequence.

Minor 2-5-1

It’s the same chord progression, but this is the minor version. The tonic is replaced by the minor chord, and the ii which is normally a minor 7th, becomes a diminished chord.

Extended 3-6-2-5-1

Notice that we are adding chords according to their order along the circle of fifths. For instance, in the key of C, the 3rd (E) has 4 sharps, the 6th (A) has 3 sharps, the 2nd (D) has 2 sharps, and the 5th (G) has one sharp.

Tritone Substitutions

We take the dominant fifth, and substitute a chord that is based on the note a tritone above. In the key of C, this means that the G7 might be replaced by a C#7. This results in a chromatic sequence (D - C# - C).

Diminished Sixths

To explain this concept, let’s start simple. For a given tonic, there’s this concept of the dominant, which provides tension. Also in jazz, chords are often played with extensions, which means that the dominant often gets a flat 9, which is a flat 6th in the tonic key.

So this creates a new scale, where some notes, (the 2, 4, flat 6, 7) belong to the “dominant” sound, and other notes, (the 1, 3, 5) belong to the “tonic” sound.

Here, we can notice that the dominant notes (the top 4 notes of a extended dominant chord) form a diminished chord. And since a diminished chords is built on minor thirds, it stays constant in any inversion.

Finally, all we have to do now is move between the tonic sound and the dominant sound. This can be done quickly, too. For example if you’re playing a descending scale, you can alternate the harmany on each step to create a nice & rich feeling of tension & release.

The Unicorn Chord aka a Diminished Major Seventh

This particular voicing creates a very unstable sound, which is great for leading us to different places. The three main uses of this are:

1. Tonic diminished, usually resolving back to the tonic.
2. Flat-3 diminished, usually coming from the major third and resolving to the second.
3. Flat-5 diminished, usually resolving to the fifth.

It’s important to mention that taken in root position, these might not always sound great. The key (pun not intended) to using this chord is to choose our voicings to create chromatic motion. This might mean taking inversions, or using drop chords.

Picardy Third

A major third at the end of a minor song.