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.
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).
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.
- 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.