Firstly, the sharps or flats tell you what key you are in. In blues most commonly it's E (4 #'s), G (1 #), A (3#'s) or c (no sharps). To learn more about key signatures/ Circle of Fifths/ Circle of Fourths, try wikipedia. The author of the book assumes you can read music or has provided tab as well.
Key signatures give you the major scale of that key so you can write it without any sharps or flats in the music itself (they're all at the start straight after the treble clef).
Here's where blues is weird. If you are playing in E, your chords will be E7, A7 and B7 ie chords based on the 1st, 4th and 5th notes of E major scale. However, over these chords you will play the E minor pentatonic or blues scales! It seems like it shouldn't work, but it does.
In blues, you don't go down four frets to C#minor (the relative minor of E/ same notes and key sig as E major, but a minor scale). Nooooo. What you do is you play a minor scale where you'd expect to see a major scale. The b3rd of the blues and major 3rd of the chord don't seem to clash.
So even though you see a piece with 4 #'s (E major), in blues you'll play an E minor blues scale over that chord!
|
