21.4 · Sevenths & Jazz

Turnarounds & blues

Put the sevenths to work. Jazz runs on loops just like pop does, but every chord is a four-note 7th. And there is one rulebreaker: the blues, where every chord gets the dominant quality.

The turnaround

I–vi–ii–V in sevenths. It ends on V7, so it hands itself back to the top; tunes loop it between choruses.

Cmaj7
Am7
Dm7
G7

Cmaj7 → Am7 → Dm7 → G7. Notice the last two chords are a ii–V aimed straight back at bar one.

Its ancestor is the 50s doo-wop loop, in triads:

Jazz up a familiar loop

Any progression takes the upgrade. The pop loop in triads, then in 7ths:

The 12-bar blues

Twelve bars, three chords, I7, IV7, V7, and every single one a dominant. By the diatonic rulebook only V should get that quality; the blues ignores it, and that friction is the sound.

C7
C7
C7
C7
F7
F7
C7
C7
G7
F7
C7
G7

Four bars home, two bars away, back home, then the V7–IV7 turnaround row. The skeleton under thousands of songs, jazz and rock alike.

Game · Name the loop

1 / 6

One of the unit's three loops, in C. First: triads or 7ths? Then: which walk?

Listen first. Then answer.

Quiz

1 / 3

Why does the turnaround loop so naturally?

Score 100% on every quiz and game to complete this lesson. A perfect run sticks: a later miss never undoes it.Past the 7th: 9, 11, 13 →