A complete example · Reharmonization · Music theory
Take a simple melody in C major, harmonized with I, IV and V. Now change chords without touching it. Over D, E7 makes it a seventh and prepares A minor.…
A complete example
Take a simple melody in C major, harmonized with I, IV and V. Now change chords without touching it. Over D, E7 makes it a seventh and prepares A minor. Over C, Am7 replaces I and resolves that E7. Over A, D7 takes the place of F: another dominant, asking for G and preparing a stronger cadence.
G7 and the final C stay, because the cadence is what gives sense to everything else. If the melody note is heard as part of the chord, the arrangement works. The result has two secondary dominants and a substitution, and the melody is still recognizable at once.