Blues
The harmonic agreement of the blues is short: everything is a dominant. Where ordinary tonal music gives a minor seventh only to the fifth degree, blues gives one to every chord, which means nothing ever properly resolves.
- everything is a dominant
- 12 bars
- the blue note moves
In which styles
- Blues
- Rock
- Jazz
- Soul
In short
In C that is C7 on the I, F7 on the IV and G7 on the V. By the rules of functional harmony that should not work: three chords all demanding resolution, none of them getting it. In the blues the tension is a permanent state rather than a direction, and the form rather than the harmony tells you where you are.
Weighted and unhurried. A blues does not go anywhere, it circles, and the twelve-bar cycle is what gives it shape.
How the style works
The shuffle is a division into three. You split each beat into three equal parts and play only the first and the third, which produces the long-short pattern that carries the whole style. Get that division wrong and the chords will not save you.
Where you run into this
- Three chords, all sevenths, for twelve bars
- A guitarist bending into a note rather than landing on it
- A phrase played three times, which is the oldest blues structure there is
What you leave out
A maj7 on the tonic. C7 contains a B flat and Cmaj7 contains a B; play the maj7 and you get a collision with the flattened seventh in the melody, and it turns into lounge music in one bar.