All blues styles mentioned in the previous section can be played with a basic 3 chord pattern. I could just tell you what those three chords are, but I think it would be in your best interest to know how these chords are formulated and found within their associated scales, that way you will have a better understanding of how to play the blues in any key.
Firstly, you need to have a basic understanding of how major scales are formulated so that you can easily find the -chord progression in the key you wish to play in. To keep it simple, we will be exploring the 12 Bar Blues in the key of C major.
The C Major scale looks like this as actual note names (letters) and scale positions (numbers):
The C Major scale looks like this as actual note names (letters) and scale positions (numbers):
The root notes of each of the three chords fall under scale positions: 1, 4 and 5, which will give you the root notes of C, F & G. If you know your chord families, then you will know that each of these root notes belong to major chords so the three chords you will play are:
So now you know the 3-chord scale positions for the 12 bar blues, you can apply this same root note progression formula to any major scale to play in different keys. For example, if you wanted to play the blues in the key of G, you simply need to map out the G major scale as illustrated below and locate the root notes of the 1st, 4th and 5th positions. In this case: G, C & D major
If you are not sure ab out how scales work, it might be a good idea to give the INTRODUCTION TO MUSIC THEORY a go. You will also get a PDF download containing all major scales and associated accidentals.