The last two lessons I’ve presented in Bass Musician Magazine have hopefully made it clear that you can use the harmonic minor scale for the ii/V/i cadence. One of the benefits of harmonic minor is that you can use the same scale form for all three chords, the same way that we use the major scale to play through the major ii/V/I.
As your ears grow more sophisticated, it’s very likely that you’ll want to expand your harmonic/melodic palette to include some of the sounds that musicians have made part of the jazz language in the last few decades. One of the most interesting devices you can learn to use is the melodic minor scale.
Construct melodic minor by simply flatting the third degree of the major scale. Another way to think of it is as a minor scale with both a major 6th and major 7th. * So D melodic minor (to be consistent with the key of our last two lessons) is spelled D E F G A B C#. (Fig. 1) This scale has a lot of cool applications on a variety of chord types, including some altered dominants and the wily M7#5. But let’s stick to our main task, using the sound of the melodic minor on the minor ii/V/i cadence.
Here’s the chord progression: E-7(b5) / A7alt / D-(M7) It turns out that only the tonic chord (spelled D F A C#) exists within the D melodic minor scale. Neither of the other two chords can be extracted from that scale (there’s no Bb, for one thing). If we really want to use melodic minor as our harmonic basis for this progression, we will have to figure out which melodic minor scale contains each of these chords.
If we were still using the major scale system, E-7(b5) (E G Bb D) would shout locrian, the 7th mode in the key of F: E F G A Bb C D. Do you see how the scale tones fill in the missing spaces between the chord tones? By making one small change in these “in-between” notes we’ll be able to generate a melodic minor sound that embraces E-7(b5). If we raise the F natural one half step to F#, we create this scale; E F# G A Bb C D. With some quick calculating, we can see that this “locrian #2” scale is the 6th mode of G melodic minor. (Fig. 2)
What about this A7alt chord? The designation “alt” is short for altered, and it generally translates to any dominant chord containing both the 5th and 9th degrees altered (b5 and/or #5 AND b9 and/or #9). These sounds are quite common in contemporary jazz, and our old friend mixolydian doesn’t work at all with these altered intervals. Melodic minor to the rescue!
Let’s construct a dominant type scale that includes ALL those altered 5ths and 9ths starting on the root A (keeping in mind that dominant chords are defined by the combination of M3 and m7):
A Bb C C# Eb F G (root, b9, #9, M3, b5, #5, m7). This scale is a thing of beauty. The first half alternates between half and whole steps while the second half contains all whole steps. This scale goes by a few names, most commonly the altered or diminished/whole tone scale. This scale is also the 7th mode of the Bb melodic minor. (Fig. 3)
So the chord/scale matchups for this ii/V/i go like this:
E-7(b5) – G melodic minor.
A7alt – Bb melodic minor.
D-(M7) – D melodic minor.
But what does this mean for us when we’re constructing walking bass lines? As long as you have at least 4 beats for each chord you can make good use of some of the spiced up flavors of the melodic minor. The F# from the G melodic minor is a delightful passing tone on the E-7(b5), for instance. The presence of the altered 5ths and 9ths on the A7alt are also noteworthy (pun intended). And the inclusion of the B natural on the D-(M7) is a welcome change from Bb, the flatted 6th. See Fig. 4 for some examples of walking lines that use the colors of the melodic minor.
The uses of melodic minor are well documented in recordings and books. Check out pianist Mark Levine’s excellent Jazz Theory in this regard. Start incorporating these sounds into your lines and you will discover some pathways through these changes that might not occur to you otherwise.
* Note that the only difference between natural, melodic, harmonic and dorian minor scales is whether the 6th and 7th degrees of each scale are major or minor.