Lesson 10 - Minor key harmonization

The use of minor keys in jazz has become more prevalent in recent years. How minor key chords are used by jazz musicians is a difficult question. The problem is created by the fact that there are three minor scales commonly used in jazz and, consequently, three sets of chords for every tonality.

The natural minor, harmonic minor, and melodic minor (ascending form) are used in jazz. The melodic minor ascends and descends in the same manner, l-2-3b-4-5-6-7-8. In this sense it is unlike the classical definition of a melodic minor scale. This form of a melodic minor is sometimes called a jazz minor.

The natural minor scale produces the same chords as the major scale a minor third above it, i.e. A natural minor has the same chords as C major.

When combined in progressions, these chords still seem to give a major sound rather than effectively producing a minor tonality.

The harmonic minor produces the following chords:

These chords produce a much more effective minor key, however the I and III chords are rarely used because of their inherent dissonance. The minor(Δ) chord is sometimes used in more progressive compositions as a I chord, but the minor seventh chord (from natural minor) is much more commonly used as the tonic chord. The III chord is usually an augmented triad rather than a seventh chord because the triad is less dissonant.

The melodic minor-or (ascending form only) produces the following chords:

Now that you have seen all the theoretical possibilities, I will narrow the choices down to the chords that are in common use in jazz progressions.

I. The tonic in minor is almost always a minor seventh (from natural minor), but the minor(maj7) chord has been used as a tonic in some progressive pieces. The minor sixth, minor ninth, and minor six/nine are sometimes seen.

II. The supertonic chord in minor keys is generally a minor seventh flat five chord (from natural and harmonic minors). The II chord is very often used in the II-V progression and the use of a minor seventh (from melodic minor) gives exactly the same chords as a major key. Consequently, the minor seventh is not often used as a II chord.

III. The mediant chord is often seen either as a major seventh (natural minor) or as an augmented triad (harmonic and melodic minor). Both forms are commonly used. The major seventh sharp-five chord is sometimes seen but is in less common practice than the augmented triad.

IV. The subdominant chord in a jazz minor composition is generally a minor seventh (natural and harmonic minor) or minor sixth chord. The IVm6 chord is an enharmonic spelling of a IIm7(b5) chord and is diatonic in a natural or harmonic minor scale.

V. The dominant chord in minor is almost always a dominant seventh chord. Notice that a sharp-five is diatonic to all three minor scales. Logically, the 7(#5) chord is very often used as a V chord in minor. (The 7(b5) chord is occasionally used but is not diatonic to the minor key, and would not be as strange a substitution if you are trying to strengthen a basic progression). The ninth degree is either sharp or flat in natural or harmonic minor. The ninth is natural in melodic minor. All of the following chords can be used and are commonly used as V chords in minor:

V7 - V7(#5) - V7(#9) - V7(b9) - V9 - V9(#5) - V7(#5b9) - V7(#5#9)

The flat five variations of a dominant seventh or a dominant ninth chord (V7(b5), V7(b5#9), V7(b5b9), V9(b5)) are sometimes seen but are not diatonic to the key.

The eleventh degree is diatonic to all minor scales and can be added to all of the V chords listed above. The thirteenth degree is flatted in all minor scales and is equivalent to a seventh sharp-five chord which has already been mentioned above.

As should be obvious through the complex analysis above, the V chord in a minor key in jazz is open to many variations and is the most malleable and colorful chord in the key.

VI. The sub-mediant chord is usually a major seventh (from natural or harmonic minor). The minor seventh flat-five chord from the melodic minor is also sometimes seen. A favorite VI chord of modern composers is the major seventh flat-five (or sharp eleven) which is diatonic to the natural and harmonic minor scales.

VII. The leading-tone chord is usually a diminished seventh from harmonic minor. This chord is often spelled as a bVlI(b9). The dominant seventh (natural minor) and minor seventh flat-five (melodic minor) chords are used less often.

Summary
Although as you have seen, many options are open for each chord in a minor jazz progression, I consider the following as the primary harmonizations of a jazz minor key:

*The symbol V7(+5±9) is shorthand for V7 with a sharp five and/or sharp nine or flat nine.

Improvisation in minor keys requires that you know the minor scale from which every chord is derived. If in doubt, the natural minor can usually get you through.

Minor key harmonization

a) natural minor

b) harmonic minor

c) melodic minor

d) primary harmonization of a minor key in jazz