20.5 · Sevenths & Jazz

Past the 7th: 9, 11, 13

The 7th came from stacking one more skip. Keep going and the odd numbers keep counting: 9, 11, 13. They're just scale tones an octave up (9 is 2, 11 is 4, 13 is 6), stacked until the whole scale is in the chord. Past 13 there's nothing left to add.

The ladder to 13

Root, skip, skip, skip, and keep skipping: C E G B D F A is 1 3 5 7 9 11 13. Tap the rungs, then hear the chord grow.

Players rarely play every rung: the root and the colors matter most, and the 11 usually sits out on major chords (it rubs against the 3). Extensions are a menu, not a stack you must finish.

The cadence, upgraded

The ii V I with color on top: ii9, V13, Imaj9. Same jobs, same pull, just more sky in each chord. This is the default grown-up voicing in jazz and neo-soul.

Quiz

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The 9th of a chord is the same letter as its…

Score 100% on every quiz and game to complete this lesson.Same chord, new shape →