A short but detailed look at the diatonic seventh chords that are derived from the three forms of the minor scale. These being the following:
A natural (pure) minor:
A B C D E F G A
A harmonic minor:
A B C D E F G# A
A melodic minor:
A B C D E F# G# A
The seventh chords generated by these three scales are as follows:
A natural minor:
(i)Am7 (ii˚)Bm7b5 (III)Cmaj7 (iv)Dm7 (v)Em7 (VI)Fmaj7 (VII)G7
A harmonic minor:
(i)Am(#7) (ii˚)Bm7b5 (III⁺)Cmaj7#5 (iv)Dm7 (V)E7 (VI)Fmaj7 (#vii˚)G#dim7
A melodic minor:
(i)Am(#7) (ii)Bm7 (III⁺)Cmaj7#5 (IV)D7 (V)E7 (#vi˚)F#m7b5 (#vii˚)G#m7b5
To recycle these seventh chords as rootless ninth chords use the following third relationships:
1) Substitute the (i) chord with the (III) chord in all forms of the scale which will give us voicings for either a minor9th chord (natural minor) or the exotic m9(#7) in harmonic and melodic minor.
2) Substitute the (iv) chord with the (VI) chord in all forms of the scale which gives us rootless voicings for either a minor9th chord (natural and harmonic minor) or a dominant 9th chord in melodic minor.
3) Substitute the (V) chord with the (#vii) chord in harmonic and melodic minor only creating a rootless 7b9 in harmonic minor or a dominant 9th chord in melodic minor.
4) We will leave the (ii) chord alone since this harmony is usually not extended in common practice.
The following chart shows voicings for the above chords using the first four strings only beginning with root position and followed by first, second and third inversions. Some are a bit difficult to play, particularly in the lower positions of the fingerboard so take it easy. Practice these voicings in the order shown and make note of the change in quality of the chords as you go from natural minor to harmonic and melodic minor. Then, the next time you encounter a minor(#7) chord or a Major7(#5) for example you will be able to choose a compatible harmonic or melodic minor scale, transposed of course to the key which generates the chord in question.