by Will C » Sat Feb 03, 2018 9:53 am
Don't forget the secondary dominant. Sorry, wash mouth with green soap....
This little "trick" crops up in a bazillion songs, especially country. You will need to master it. The dominant is the 5th, so in C you are talking about G, or G7 if you use the dom7 instead. If you go to the dominant of the dominant (the dominant of G is D) that's the secondary dominant.
So, whereas in C you'd normally use Dm, if you go to D major instead it bounces you to G, which bounces you back to C. You can follow that ad nauseam:
You can go to E from C. E is the dominant of A, so go next to A, which bounces you to D, thence to G, then back to C. This trick lies at the heart of so many non-trivial chord sequences in popular music, so it's the next step after the three-chord trick. If you can make sense of it you will find a whole new field of stuff opens up for you like a flower.
Look up "circle of fifths" - it shows all the different keys around a circle, starting with C at the top. All the sharps going clockwise, all the flats going anti-clockwise. They meet in the middle. For a fifth(dominant) go clockwise, for a fourth go anti-clockwise. You can see how changing from C to E, for example, can bring you back to C just by walking back around the circle, one step at a time.
Basil will now step in and correct me in a million tiny ways, as befits the master of harmony theory, but this is essentially correct and a really useful tool to have in your toolbox.
St Ives, Cambridgeshire