How to Draw Attention to Common Secondary Dominants on the Guitar
Musicians and guitarists use secondary dominants on almost any chord in a key to provide some variety to a progression and to give some temporary focus to another chord. For example, the D7 chord has a different sound quality than a simple D minor chord, which is what you normally find in the key of C.
Because the chord has a dominant function, it draws attention to the following G7 chord. It’s as if the chord progression temporarily changes keys to G.
You can lead to almost any chord with its own dominant. A chord’s dominant is a major chord or dominant 7th chord that’s a 5th away from the chord itself. You could lead to D with A7, which is five steps away from D, the interval of a 5th.
Keep going! The 5th of A is E, and an E7 chord can lead to any type of A chord. Take a look at an example of E7 leading to A7 in a series of dominant 7th chords that begins on E7 and moves to C.
Another common secondary dominant progression is I7-IV. In C major, this progression is C7 moving to F. An example of this secondary dominant’s use is in the larger progression F-G-C-C7-F-G-C. The progression is in C major, but the C7 chord is functioning as a dominant 7th of the F chord.
The most common secondary dominants are the ones you see here — those that lead to I, ii, IV, V, and vi. Musicians generally don’t use secondary dominants that lead to vii♭ó5, and although V7 of iii is possible, it isn’t very common.