For example, in C major tonality, the dominant chord is G7. If, in this tonality, A7 appears, these chords would be a “secondary dominant”, because it is a dominant that solves in D, not in C (our tonic, in this case).
Pay attention that secondary dominants are not part of the natural harmonic field. They are auxiliary chords, and they serve only to “prepare” a cadence for another degree of harmonic field.
Several times, secondary dominants are used to anticipate the natural dominant in the song. For example, in the previous case, the natural dominant was G7, so we can play before itself another dominant that prepares our way to G.
Example of secondary dominants
The dominant of G is D7. Thus we would have the sequence | D7 | G7 | C |, where D7 is the secondary dominant. This dominant is also called “Dominant of the dominant”, since it serves as dominant to another dominant.
In terms of nomenclature, normally we use the notation V7/V7 or V7/V to highlight that this is about a secondary dominant to another dominant (for fifth degree). If it was, for example, secondary dominant that would prepare to the fourth degree, we would write V7/IV.
How to use secondary dominants
Very well, the concept of secondary dominants is clear. Now we will show the implications that this concept can have.
As V7 dominant is always a fifth above the chord that it will solve, we can “play” with successive circle of fifths. In the previous case, we played D7 before G7, but we could also play A7 before D7 and E7 before A7, creating the following sequence:
| E7 | A7 | D7 | G7 | C |
This sequence is a preparation after another one, which was solved in the end in C.
First, E7 prepared to A, but A was with seventh, preparing to D, and then successively till finishing in C. This kind of progression is really used in Jazz.
As we saw, it is about “extended dominants”, because they form a cycle of fifths (or fourth, depending on which side you are looking). The concept is simple, they are just dominants. We can improvise in them using the mixolydian mode of each dominant, or all the other approaches that we will study (in future topics).
Of course that this improvisation is not always easy, because these passages can be really fast, what make our solo hard. This is why is really important to train a lot in this theme, because secondary dominants appear a lot in styles that are rich harmonically (like Jazz, Fusion, Bossanova, MPB, etc.). When we will analyze complete songs here in the website, you can be sure that secondary dominants will appear a lot!
Go to: Extended chord
Back to: Module 7