Inside Music: Modes Revisited, and Revised

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by Richard Middleton

"Modes Revisited, and Revised"

I thought I’d expand a bit on my earlier discussions of major scale modes and push into some new territory. The material in this article assumes you know something about the modes; if these concepts are unfamiliar to you, refer to "Inside Major Scale Modes," Parts I and II, in the Inside Music Archive.

The major scale is made of a series of whole-steps and half-steps, arranged in a specific order: W-W-H-W-W-W-H (W = whole-step, H = half-step). The modes of the major scale all use this order as well, but mode each begins in a different place in the series. We can say, then, that the building blocks of these scales are major and minor seconds (a whole-step is a major second, a half-step is a minor second).

The building blocks of chords are thirds. By that, I mean that you can think of a chord as a stack of major and minor thirds. For example, CMaj7 is C, E, G, and B, which form the following thirds: C to E is a major third, E to G is a minor third, and G to B is a major third. A shorthand way to remember these is “major, minor, major.” All Maj7 chords are built the same way. For example, a GMaj7 is also made of thirds that are “major, minor, major”: G to B is major, B to D is minor, and D to F-sharp is major.
Other types of chords use a different combination of thirds. For example, C7 is C, E, G, and B-flat. Here, the thirds are “major, minor, minor”: C to E, E to G, G to B-flat. All “7” chords follow this formula.

Here are the “third formulas” for the four most common seventh chords:
Maj7: maj, min, maj
min7: min, maj, min
dom7: maj, min, min
min7flat5: min, min, maj

As we saw earlier, scales are made of major and minor seconds. If you combine seconds together, you get thirds. Wherever there’s a W-W combination in a scale, that’s a major third; where you see a W-H or a H-W, that’s a minor third. In the minor third, notice that it doesn’t matter whether the half-step or the whole-step comes first. All that matters is that the total span is one and a half steps. This means that if you’re playing a scale over a chord that has a minor third in it, you have a choice of whether to play a H-W or a W-H to “fill in” the minor third with your scale.

For example, over a CMaj7, the minor third in the middle is between E and G. You can “fill in” that third with an F-natural (forming a C Ionian scale), or an F-sharp (forming a C Lydian scale). For a Cmin7, you have more choices, because there are two minor thirds in the chord: C to E-flat, and G to B-flat. You can fill in the upper third with an A-natural (forming a C Dorian scale), or an A-flat (forming a C Aeolian, or natural minor, scale). In the lower third, you can play a D-natural (which is included in both the Dorian and Aeolian scales mentioned above), or a D-flat (which appears in the C Phrygian scale).

Let’s look now at the dom7 chord. The only diatonic mode that “works” with dom7 is the Mixolydian mode (like a major scale, but with a minor 7th). However, if we apply the principle of “filling in” minor thirds in creative ways, we can come up with some interesting scale possibilities that fall outside the diatonic modal system.

Notice that dom7 chords have two minor thirds. For example, in C7, the two minor thirds are E to G, and G to B-flat. Normally, the lower third is filled with a H-W combination (producing, in this case, F-natural), and the higher with a W-H (or, in this case, A-natural). However, we can flip these around. We can change the F to an F-sharp if we wish, giving us this scale: C, D, E, F-sharp, G, A, B-flat. Try playing this scale on your instrument. Sounds cool, no? Change the F-sharp back to F-natural, and now change the A to an A-flat and play the scale again. A very different sound.

As I said, these alterations don’t fall within any of the usual major scale modes. They are closely related to the modes, but they have been “revised” to become entirely new scales. Yet they work perfectly well over the C7 chord. Why? Because these scales both contain all the chord tones (C, E, G, B-flat), and move in the step-wise motion that we’re used to in diatonic scales. You have similar flexibility when playing over min7flat5 chords; see if you can figure out those combinations on your own.

If we bend the rules even further, we come with some wilder, yet still entirely logical scale-chord relationships. We’ve played around with the two minor thirds in our C7 chord; now, let’s look at the major third at the bottom, between C and E. A major third is made of two whole-steps, but we don’t have to divide it into two equal pieces. We can also “fill in” that major third like this: H-W-H. This means we can play a scale over our C7 that goes like this: C, D-flat, E-flat, E, etc. If we combine these new tones with the F-sharp we used earlier, we get a very interesting scale indeed: C, D-flat, E-flat, E, F-sharp, G, A, B-flat, C. Play that on your instrument. Groovy, no?

This scale sounds much more exotic than our earlier revisions, because it has so many half-steps, because it has eight tones instead of seven, and because it is, in fact, completely symmetrical: it’s just a series of alternating half-steps and whole-steps. This is one form of what is called a “diminished scale” (which works, not surprisingly, very well over diminished chords). Because of its symmetry, it creates the impression that there is no true tonic or tonal center, and can be a very powerful addition to one’s improvisational toolkit, both for melodic lines and chord voicings.

By the way, my decision to illustrate these scale revisions using a dom7 chord is not an arbitrary one. As it turns out, such alterations are quite common with dom7 chords (often with corresponding altered extensions in the chord itself) because they’re often used to transition between chords and between keys, making them prime candidates for increasing the dissonance and tension to set up a subsequent resolution.

The topic of scales beyond the usual modes is rich and deep, and I encourage you to read and experiment further on your own. They can add a lot of spice and interest to your music. Enjoy!

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