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CYCLE OF FIFTHS
In the previous tutorial I mentioned that diatonic root movement by a third is weak as the second chord has three out of four notes the same as the previous one. The strongest root movement is downwards by a perfect fifth (same as upwards by a fourth). If we continue moving in fifths we have a progression which goes through all twelve notes available in western music and arrives back where it started. This is called the cycle of 5ths, or sometimes the cycle of 4ths. This is because if you progess round the cycle the other way (anticlockwise) the intervals are 4ths instead of 5ths.
Ex 3a: Cycle (or circle) of fifths - starting at C go anti-clockwise in to see the tonic notes of the key and the number of sharps or flats in the key signature.
A IIm7-V7-I progression has a root movement that follows the cycle of fifths (D - G - C). By substituting chord I with chord III in ex 2e we continue this cycle further (E - A - D - G - C). Carrying on this pattern an entire cycle can be made up of IIm7-V7s (ex 3b)
| Em7-A7 | Dm7-G7 | Cm7-F7 | Bbm7-Eb7 | Abm7-Db7 | F#m7-B7 | Em7-A7 |
| (key: D) | (key: C) | (key: Bb) | (key: Ab) | (key: Gb) | (key: E) | (key: D) |
ex 3b: Cycle of fifths (IIm7-V7-Is)
If each apparent IIm7-V7 is given a key centre, the progression contains 6 key centres each a whole tone lower than the previous one. There are therefore two different IIm7-V7 cycles, a semitone apart. (ex. 3b and c).
| Ebm7-Ab7 | C#m7-F#7 | Bm7-E7 | Am7-D7 | Gm7-C7 | Fm7-Bb7 | Ebm7-Ab7 |
| (key: Db) | (key: B) | (key: A) | (key: G) | (key: F) | (key: Eb) | (key: Db) |
ex 3c: Cycle of fifths (IIm7-V7-Is), using the 6 key centres not used in ex 3b.
If we continue the process of creating secondary dominants (see above, ex 2f) we arrive at thecycle of fifths of dominant 7 chords (ex 3a-2). This sequence is very common in jazz. A very typical example is the bridge of Gershwin's I Got Rhythm
(chapter 10). There are countless jazz tunes based on the chord sequence of I Got Rhythm
: Lester Leaps In
, Anthropology
, Cottontail
and many more.
Note in ex 3d the downward semitone resolution from 7th to 3rd and 3rd to 7th. Although the 3rd in a dominant 7th chord is a leading note and would normally resolve up a step, this chromatic descending line is often used as a feature of the cycle of fifths.
N.B. when analysing a tune and part of a cycle of fifths appears where dominant 7th chords are changing quickly it may be simpler to specify only the final key centre rather than a key centre for each chord, see ex 3d below and chapter 13 - I Got Rhythm
chord changes
ex 3d: Analysis of a partial cycle.
What is the difference between a circle of fifths and a Cycle of 4ths (fourths)