Lydian dominant mode and Hexatonic Scale

Another possible application for the hexatonic scale, in addition to what we’ve already seen, is in the Lydian Dominant chord.

“Wow, now it just got too hard for me! I won’t understand anything!”. Calm down, you will understand, it is very simple. What is the Lydian scale? It is the major scale with an augmented fourth. If you didn’t know that, just check it out in the music modes section; do that scale and observe.

Let’s just recap, then. If the key is C major, the fourth degree chord is Fmaj7 and the mode used over F is the Lydian mode. Nothing new so far.

If we exchange this major seventh of the Fmaj7 for a minor seventh, we would be left with the F7 chord. In this case, the scale we used before (Lydian mode) would have a change in its seventh degree (it would cease to be major and become minor). This new scale (Lydian with minor seventh) is called the Lydian Dominant scale, because the resulting chord has become a major chord with a minor seventh (F7).

Notice that the lowering of the seventh generated a tritone, that’s why the chord become dominant.

Okay, the great result of all of this is that, when the fourth degree chord is a dominant chord, the scale played on top of it has an augmented fourth (from the Lydian mode) and a minor seventh (from the dominant structure), looking very similar to the hexatonic scale!

Comparing the two scales

In fact, the only note that the hexatonic scale has that is not in the Lydian Dominant scale is the augmented fifth degree. Compare the F Lydian dominant with the F hexatonic scale below:

  • Notes of the F Lydian Dominant scale: F, G, A, B, C, D, D#
  • Notes of the F Hexatonic scale: F, G, A, B, C#, D#

Therefore, due to this affinity, we conclude that the hexatonic scale can be used on top of Lydian dominant chords, as we wanted to demonstrate!

Now, let’s continue this logic. Where does this Lydian dominant chord come from? In what context does it exist? It is present in the melodic minor key. See the C melodic minor key below:

melodic minor key

Notice how the fourth degree is a major chord with the minor seventh! (In other words, a Lydian dominant). Therefore, the Lydian dominant comes from the melodic minor context. This leads us to conclude some things. Breathe, calm down and relax. There, now we can continue.

We have already seen that the F Lydian dominant scale is the mode that fits over F7 when F is the fourth degree of the tonality. And what is the scale that should be played over the first degree (CmM7) in this case? It’s the C melodic minor scale, right? After all, this key is generated over this scale!

So my friend, this means that the Lydian dominant scale is the fourth mode of the melodic minor scale. In other words, the F Lydian dominant scale is the C melodic minor scale played from its fourth degree.

We are doing the same thing here as we did in music modes, that is, we are playing a scale starting from other degrees besides the first. If it is difficult to understand, read the article on music modes and then return here. The idea will be much clearer.

So, let’s compare the notes of the C melodic minor with the F Lydian dominant scale:

  • Notes of the C melodic minor scale: C, D, Eb, F, G, A, B
  • Notes of the F Lydian dominant scale:   F, G, A, B, C, D, Eb

They are exactly the same notes. Did you notice that the C melodic minor scale is a fifth above F? Remember that we taught you how to use the melodic minor a fifth above unaltered dominant chords?

Well then, there is an explanation for that! F7 is an unaltered dominant, right?! The idea is the following: when playing the melodic minor scale a fifth above an unaltered dominant, we are making that dominant sound as if it were a fourth degree blues (IV7). For example, let’s assume that we are improvising over the progression:

| Dm7 | G7 | C |

The tonality here is C major, but over G7 we can play the D melodic minor scale, as we already know. By doing so, we are taking advantage of the G7 chord to “trick” the listener into thinking that G7 is a IV degree blues. This is equivalent to thinking that the tonality has become (momentarily) D melodic minor, where G7 is acting as fourth degree IV7 (and no longer as V7 of C).

Of course, this is not the only explanation for us being able to use the melodic minor scale one fifth above the dominant. Many musicians prefer to think only that this D melodic minor scale generates an alteration (augmented fourth) over the G7 chord.

Regardless of the explanation you prefer, the important thing is not to be restricted to a single line of reasoning, because sometimes we can explore hidden resources and generate very attractive sounds when thinking beyond common sense. Never block your mind when it comes to music!

Affinity between hexatonic and Lydian dominant

Well, back to the idea of Lydian dominant, since we are making G7 sound like IV7, we can also try to play the hexatonic on top of it, as we have already seen that there is more affinity between the hexatonic and the  Lydian dominant mode (IV7) than between the hexatonic and Mixolydian dominant (V7). In short, when you are going to apply the hexatonic scale on top of an unaltered dominant V7, try to mix the melodic minor scale a fifth above in your solo.

This combination is very good, because it makes the hexatonic more attractive! The melodic minor one fifth above can make the V7 have another momentary function (IV7), which is more interesting for the hexatonic. In practice, the hexatonic scale does not usually appear alone, not least because the Lydian dominant (IV7), or dominant with augmented fourth chords, are not so common.

So jazz and bossa nova musicians like to add a small dose of hexatonic mixed with other things (mainly the melodic minor one fifth above), to give it this spice that we just explained. Many don’t even know why that is!

Just to conclude, notice that there are only two possible hexatonic scales (C and C#); the rest are identical to these, starting from other degrees. This is useful to observe when making an improvisation, as it increases our field of vision. Instead of thinking of G hexatonic, for example, you can think of D# hexatonic, which is identical.

So, when you want to merge the scales of G hexatonic and D melodic minor, for example, you can think of D melodic minor and D# hexatonic (it is closer and better to visualize). There’s a tip for you!

Well, the subject here was enough to blow your mind! But the concept is not so complicated when we put all the pieces together well. With a little practice, these concepts will go from your head and into your blood!

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