A Structural Device
The classic rock'n roller Buddy Holly used the Three Chord Trick a lot in his songwriting.
His tune 'Everyday' [ which I have put into the Key of C Major for clarity ] uses only the chords C , F and G through the verse and chorus - couldn't be much simpler.
The 'middle eight' of this tune however goes like this : -
( after a 'lead-in' | C / C7 / | )
| F / / / | F / F7 / | Bb / / / | Bb / Bb7 / |
| Eb / / / | Eb / Eb7 / | Ab / / / | G7 / / / |
Apart from the F at the beginning and the G7 at the end none
of these chords are even in the Key of C Major - What is going on ?
The answer is a series of Key Changes which are following a time honored structural device known as the ' Cycle of Fifths ' [ sometimes called Circle of Fifths ]
Breaking this middle eight down shows another device
' Making the Root into a Dominant Seventh ' which is sometimes used to 'force' a Key Change.
In the 'lead-in' to this middle eight C is the Root Key - this chord then changes to C7 which happens to be the Dominant Seventh chord of the next Key which is F Major.
F becomes the new Root Key for a bar and a half - but then F7 heralds another Key Change [ F7 is the Dominant Seventh in the key of Bb ]
Bb then becomes the new Root Key for a bar and a half followed by Bb7 pointing up a Key Change to Eb [ Bb7 is the Dominant Seventh in the Key of Eb ]
Eb then becomes the new Root Key for a bar and a half followed by Eb7 indicating a Key Change to Ab [ Eb7 is the Dominant Seventh in the Key of Ab ]
After a bar in the key of Ab the cycle is broken by dropping down a semitone to G7 [ this is the Dominant seventh of the original key C Major ]
The song then carries on in the key of C.
If you look at the diagram you can see the structure of this middle eight by starting on C and going anti-clockwise [ in the direction of '4ths' ] as far as Ab then jumping across to G.
The Cycle Of Fifths
If you were to start on C and go clockwise [ in the direction
of ' 5ths ' ] as far as E playing straight majors you would have the chords
to the Jimi Hendrix tune ' Hey Joe ' - this song demonstrates another example
of each chord change being , in effect , a Key Change.
What do the songs ' Parisienne Walkways ' by Gary Moore/Thin Lizzie and ' I Will Survive ' by Gloria Gaynor have in common ?
If you know these tunes you might say next to nothing ( they sound pretty different ) In fact they have almost identical chord sequences based on the cycle of fifths.
[ its not that one song copied the chords of the other - this sequence has been used from the time of Bach ]
This is different to Example 1 in that this time there are no Key Changes. Here's the sequence : -
| Am / / / | Dm / / / | G / / / | C / / / |
| F / / / | Bm7b5 / / / | E7 / / / | E7 / / / |
Again going anti-clockwise in the diagram we start on A -
go round as far as F and then jump across to B then carry on going anti-clockwise.
The Key structure is ' A Natural Minor ' with the Dominant 7th [ E7 ] added.
By careful choice of chords and jumping across at the right point we can use the Cycle of Fifths device and still stay in one Key.
Notice that the 'jump' across to B results in only a semitone difference than if we'd carried on round the cycle to Bb ( which would have taken us out of the key structure ) - this makes for nice , even bass movement throughout the sequence.
This structural device seems to crop up in almost all genres of music - it is particularly prevalent in jazz.
It is useful to know about these two different ways of using the device - Bear in mind that although the device is called the cycle of fifths most songs that use it seem to go in the anti-clockwise direction of '4ths'.
Going round the complete cycle is obviously theoretically possible (12 changes) but in practice it starts to sound a bit vague and boring so usually a jump across is used at some stage.
To solo over the top of this structure would involve, in Example 1 style pieces, following the Key Changes [ a different scale for each key ] or selecting specific notes from each chord as the sequence goes through.
In Example 2 style pieces you just have to find the key structure that's being used and use the scale that goes with that [ i.e. in the above example the scale of A Natural Minor ]
Try to learn some tunes that use this device (there are lots of them) - or try to make up some for yourself.