Chord sequence
D♭maj7 Ddim7 E♭m7 D7
In every key
Four-note rootless voicings in their two forms, with the 3rd or the 7th on the bottom, played over the root.
Heard in Db major
Over Dbmaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.
Over Ddim7 · ♯i°7
Mode 7 of Harmonic Minor
Over Ebm7 · ii7
Mode 2 of Major
Over D7 · subV7
Mode 4 of Melodic Minor