What a sequence is
A model of two or more chords (and often a melodic motif) repeated starting from different degrees. The voices repeat the same movement: this is why the sequence is both predictable and driving.
Main sequences
- Diatonic descending fifths (circle): C – F – B° – Em – Am – Dm – G – C (I IV vii° iii vi ii V I). In A minor: Am – Dm – G – C – F – Bm7b5 – E7 – Am.
- With sevenths: Cmaj7 Fmaj7 Bm7b5 Em7 Am7 Dm7 G7 C: the sevenths are prepared and resolved in a chain.
- Pachelbel (fourth down, second up): C – G – Am – Em – F – C – F – G.
- Descending thirds: C – Am – F – Dm – G (I vi IV ii V).
- Ascending 5–6: C – Am/C – Dm – Bdim/D – Em, the bass rises by step.
- Extended dominants: E7 – A7 – D7 – G7 – C, the chromatic version of the circle.
Rules
- In a diatonic sequence the chord quality changes (major, minor, diminished) because you stay in the scale; in a real sequence you transpose everything exactly, and you leave the key (it is a means of modulating).
- Two or three repetitions are enough: by the third the listener has understood, by the fourth they are bored. Break the model before the cadence.
Real example
“I Will Survive” (Gloria Gaynor, 1978) is in A minor and runs through the entire circle of fifths: Am Dm7 G Cmaj7 Fmaj7 Bm7b5 Esus4 E. The same pattern returns in countless Baroque pieces, starting with Vivaldi.