Secondary Dominants and Inside to Outside Scale Choices

from Chapter 32 of An Approach To Jazz Piano

Dominant scales can either reflect the tonality of the key center or can imply a direction away from it. The direction away from a tonal center using the dominant scale/chord as the medium, can be either towards the flat direction, or towards the sharp direction. A combination using elements of both directions may be used to modify one direction or the other. In Figure 1 the cycle of sharps and flats is presented to help illustrate direction ideas.

Figure 1

If G7/mixolydian is the most inside dominant 7th chord/scale in C, G altered dominant has the most notes out of the key of C that a G7 can have while still retaining a dominant 7th quality (see Figure 2).

Figure 2

Before outlining directional intent in secondary dominants, it is necessary to discuss the primary dominant (G7 in C major) in order to establish a working order of dominant scales.  This working order of dominant scales will include those that are more inside the key and will progress incrementally to those that have a more outward direction. Even if the order is only loosely defined it should benefit the thinking behind scale choices when improvising and composing. A problem that many beginning improvisors have is that there is no graduation of dominant scale choice used.

As a result, many improvisers often play either mixolydian for an inside dominant (mistakenly in the secondary dominants of III7, IV7, VI7 and VII7) or go directly to the altered dominant scale. As a result, the more inside scale choices are never really explored, and understanding and expression can be limited.

When working with dominant harmony, the two extremes of the inside-the-key and outside-the-key direction respectively as stated, are the dominant scales of mixolydian and altered dominant. All the other dominant scales between those two extremes, use combinations of altered extensions, and, have a more or less defined order of “in-ness” and “out-ness” of a key by virtue of the notes in those chord/scales that are in or out of that key.

The looseness of definition arises from the fact that “inside” notes like 9 can be combined with altered extensions like #11 and b13. The same is true of the 13 (an “inside” tone) which can be combined with b9, #9, and #11. This is where the term: “color” in melody and harmony comes in to play (see figure 32-5). In a dominant chord, the 9 and/or 13 can be considered: “bright” (or neutral) and are inside the key. Altered tones of b9, #9, #11, and b13 are often considered “dark” and create an intensity, and, have a tendency to move.

For example:

• in a V7(b9), the b9 tends to fall to the root.
• in a V7(#9), the #9 tends to rise a half step to resolve to the major 7th of the tonic—or will often fall to b9 and resolve from there.
• in a V7(#11) (often with a 9th), the #11 tends to rise. This extension often is considered bright or dark depending on the context—it is definitely intense.
• A V7(b13) chord (often with extensions of a 9th or b9, (and/or #9) and/or #11 is considered darker—with b13 implying the minor third of the intended tonic.

Figure 3 (32-3) outlines a proposed order for an inside-to-outside order of dominant 7th scales. The example used will be a G7 which is the primary dominant of C major. 

Figure 3