Reharmonizing a song

The original progression

The first song from the Beginner course: verse G, D, Em, C; chorus C, G, D, G.

Step 1: the sevenths

Each chord takes its seventh from the key of G: G → Gmaj7, Em → Em7, C → Cmaj7. D becomes D7: it’s the dominant.

Step 2: the verse

Replace D with its relative, Bm7: the bass walks down G, B, E, C. Softer, more jazz.

B minor 7Listen to B minor 7

Step 3: the chorus

Before the last G, add a ii-V: Am7, D7. Then, the second time through, replace D7 with its tritone substitution, A♭7: the bass moves down A, A♭, G.

A♭7Listen to A♭7

Step 4: the voicings

Play everything in shell voicings or drop 2, with no six-string chords. For each chord, pick the shape closest to the previous one: the progression should glide, not jump.

The song

1. Reharmonized verse, twice.
2. Reharmonized chorus, with the ii-V, then the A♭7.
3. Original verse, once, to hear the difference, then reharmonized to finish.

Sing the melody, or hum it: it still fits over the new progression. That’s the proof the reharmonization works.

You’ve got it when…

• You can explain each change: sevenths, relative, ii-V and tritone substitution
• You play the reharmonized progression in voicings, with no six-string chords
• You play the whole song at 70, without stopping