HARMONIC EXPANSIONS

CHAPTER 4: INSERTING PRE-DOMINANTS AND THE CIRCLE PROGRESSION
4.1 Introduction




In this chapter we will be taking a journey around the circle of fifths with the progression vi ii V I. Listen to this progression in the above videos. It appears in popular music and jazz as well as "classical music" (in the broad sense). In fact jazz musicians diligently practice phrases ending with the last three chords, ii V I, in all keys.

To explain this progression's relationship to the circle of fifths, first notice that the roots of these chords progress by descending perfect fifths. See the illustration to the left.

Because the relationship between the roots of these chords is the same as the relationship between keys on the circle of fifths, this progression can be plotted on a circle of fifths for any particular key. Think of letter names on the circle of fifths as roots of chords rather than keys as you watch the video on the right. It is an interesting fact that in western music the roots of chords tend to go counterclockwise around the circle. Roman numerals can label the letter names of the roots of the seven diatonic triads of a particular key (see below). At this point the vi ii V I counterclockwise progression can be identified among the roots of the other triads in the key.

Having illustrated V -I extensively in previous chapters, Chapter 4 will begin by describing ii, IV and ii6 as pre-dominant harmonies. Then the vi chord will be inserted before ii and ii6 to complete the circle progression, vi ii V I.

In Chapter 4 the fundamental harmonic progression will be expanded by inserting chords between the initial tonic and the dominant. Since chords are usually thought of as vertical, expansions by the insertion of chords contrast with Chapters 1 and 2 in which expansions were made by more melodic, horizontal or linear means.

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