The minor keys offer a diverse sonic palette for you to use in improvisation. The darker quality of the tonal sequence gives you a cool sound and the minor keys are very versatile over different chord changes. This lesson will focus on some basic applications of minor keys in different scenarios so you can start to use these keys effectively.
Before we begin lets go over a brief background on the minor keys. It’s extremely important not to think of minor keys as a variation of the major keys. Frequently I hear musicians say “oh yeah, you just flat the 3 and now you have minor” which technically is correct; however, you could also say “oh yeah, just raise the 3 and now you have major (from minor).” It’s very chicken-and-egg in describing the two. Minor and Major are relative. You can take the same group of notes and play them in both a major and minor key depending on the sequence. For example: A B C D E F G played from A to A’ would be A relative minor also known as the A-Aeolian mode. Playing the same notes from C to C’ would be C major, also known as C-Ionian mode. A natural minor is the relative minor key to C-major. The video example shows me playing both the A natural minor and the C major scales next to each other.
Video 1: Playing A natural minor and C major
Throughout history composers noticed that the V-I resolution in the natural minor key was stronger if the changed the naturally minor V (in A natural minor the V would be Em7) to a dominant chord, thereby raising the 3rd of that particular triad to (changing Em7 to E7). In this case the change would be from a G natural to a G sharp. This change transforms the sound of the scale and is called harmonic minor. The notes would be A B C D E F G# A.
Video 2: Playing A natural minor and A harmonic minor
There is a third variation known as the melodic minor. This form raises the 6th of the harmonic minor giving A B C D E F# G# A. Classically the melodic minor is used in conjunction with the natural minor. When a line is ascending the melodic minor is used since it contains leading tones to the root. While descending the natural minor is used. For jazz improvisation we do not use this classical approach with different ascending and descending forms. Rather, it is only the melodic minor form (frequently referred to as the jazz melodic minor).
Video 3: Playing A natural minor, A harmonic minor and A melodic minor
Now that we have a bit of background on what minor is, how do we use it? We’re going to focus on the melodic minor in this lesson, and one of the best places to start is with arpeggios. Books have been written on using arpeggios in improvisation, but generally arpeggios are used to create chordal sounds through time. It is a more linear way to play (as opposed to vertically with chords) and very familiar to bassists since we often imply chord changes with our walking lines. In soloing arpeggios are very useful for breaking up scalar lines and for changing quickly between registers.
Since arpeggios are linear and are made of chord tones they can provide you with a high degree of control in your soloing in terms of how the entire band sounds. Playing certain melodic minor arpeggios over certain chord structures can change the entire sound of what is being played. Let me repeat that, as a soloist (or even in our walking bass lines) the correct usage of melodic minor arpeggios can modulate the sound of the entire band. Pretty cool, right?
Doing this is not difficult, but you need to become a chord-substitution guru. For example, if you want to create a Am9 sound and the other musicians are playing an Am7 chord you can play a Cmaj7 arpeggio to get this sound. Here’s how it breaks down:
Am7 = A C E G
Cmaj7 = C E G B
Am7 + Cmaj7 = A C E G B = Am9
For emphasis you could play the descending arpeggio to accent the B at the beginning of the measure. You do not need to play the root A in the arpeggio since the band is providing that sound. This is a very advanced melodic concept but will provide you a great deal of improvisational agility once you master it. To practice learning chord substitutions I would recommend writing out a few chords and seeing how many other chords it could be (with inversions etc).
For example: Cm6 = Am7b5 = F9 (with no root) = B7b9 (with no root)
Start experimenting with the sounds to see how this works. The chart below shows the resulting sound from playing each of the melodic minor arpeggios in the A melodic minor form over D7 and Am. The real trick to this technique is in the phrasing. You have to phrase the arpeggio in such a way that the underlying chord qualities are still there and blend with the new tonal arrangements in the arpeggio. Like most things, this is something that only comes with practice.
In the next lesson we’ll cover using the melodic minor scales over functioning dominant seventh chords to control tension in a solo or walking line.