Chuck Anderson identifies key concepts for ‘Unresolved Modulation in Harmony’ – his Jazz Guitar Improvisation Lesson Series continues.
Today’s harmonic topic is called Unresolved or Unresolved Modulation. It is identical to Internal Modulation with one important difference. Internal Modulation represents a temporary key change by using both Active and Passive chords as it moves into a new temporary key.
Unresolved Modulation uses only Active chords from the new temporary key.
In Full Diatonic chords, the Active chords are the V, II, IV, and VII. In the key of C, the Active chords would be G7, Dm7, Fmaj7, and B
After an Unresolved Modulation, the progression can return to the original key or go on to a different key or a different principle.
Without question, the most common Unresolved Modulation is a II V in a key other than the original key.
Example: Original key is C
Cmaj7 – Am7 – Dm7 – G7 – Bbm7 – Eb7 – Dm7 – G7
Note that the 5th and 6th chord are the II and V of the key of Ab. Since both chords are Active in Ab, they are considered an Unresolved II V.