Secondary Dominants
The first step outside the key, and the easiest one to hear. A secondary dominant borrows the pull of a V chord and aims it at something other than home, which makes an ordinary progression suddenly sound like it has a plan.
- 1 chord from outside
- V of something else
- one bar of direction
which styles use it
- Jazz
- Gospel
- Soul & R&B
- Pop
In short
In C major the V chord is G, and it points at C. A secondary dominant asks what the V of some other chord in the key would be, and uses that instead. The V of the ii chord, Dm, would be A7. Play A7 before Dm and the Dm arrives like a destination rather than a passing chord. The borrowed chord uses a note from outside the key, which is what gives it the lift.
It is the cheapest way to make four ordinary chords sound considered. One extra chord, one note from outside, and the progression gains a sense of purpose it did not have.
Where it sits in the sentence
- Before the target, never after
A secondary dominant only works pointing forward at the chord it belongs to.
- One at a time
A chain of them is a jazz device and it sounds like one. In pop, one is usually the right number.
- Watch the new note
The note from outside the key is the whole effect. Put it somewhere audible, not buried in the middle of the chord.
Where you run into this
- In almost every jazz standard, where chains of them are ordinary.
- In gospel and soul, where the V of IV before a chorus is a signature move.
- In pop bridges, where one borrowed dominant is often the only thing separating the bridge from the verse.
The versions side by side
A four chord progression played plain, then with a secondary dominant before the second chord, then with one before the fourth. Same destination each time, different amount of push.
Keep going
Everything in harmony
- Secondary Dominants
- Modal Interchange
- Chromatic Harmony
- Modulation
- Modal Harmony
- Harmonic Sequences