Once we get into chord progressions and ‘diatonic ... First, a jazzy II-V-I in C major would be Dm7-G7-Cmaj7. Then, if we move the G7 up a tritone/aug 4th/dim 5th, we will get a Db7.

The dominant seventh of a V chord can be shown by the symbol V7. For example, G7 is made by taking the major triad of G (G - B - D) and adding an F (G - B - D - F). A cadence is formed by two ...