18.3 · Cadences & Color

Secondary dominants

The dominant 7th pushes hard toward the chord a fifth below. Jazz and pop share one trick: any chord can have a dominant of its own. To make V feel important, put V's own dominant in front of it. That chord is a secondary dominant, written V/V: "five of five".

Meet the dominant 7th

A dominant 7th is the V triad with one more third on top: G B D gains an F. The added note gives V a harder push toward home.

43GBD7The plain V, then home.433GBDF10V plus F, then home: a harder push.

A dominant for V

The same phrase twice. In the second pass, plain ii becomes D7, aimed straight at G.

C
Dm
G
C

I ii V I: gentle, fully diatonic.

C
D7
G
C

I V/V V I: D7 doesn't belong to C major (that F♯ gives it away), and that's exactly why V lands harder.

V of IV: home becomes a dominant

The classic C7 → F release is a secondary dominant: V of IV. Home turns dominant, pointed at its neighbor.

C
C7
F
C

I V/IV IV I: the moment C picks up a B♭, it stops being home and starts pushing toward F.

Chain them

Secondary dominants chain: D7 pushes to G7, which pushes to C. Jazz turnarounds are built from exactly this chain of fifths.

Quiz

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V/V means…

Score 100% on every quiz and game to complete this lesson. A perfect run sticks: a later miss never undoes it.The key change →