Ah, the blues… What blues has always fascinated me is how emotional it is while being relatively simple (or actually complicated!) theoretically. Blues in C, play C blues scale. Blues in F, play F blues scale. Of course there are more to be discovered beyond the blues scale alone, it alone covers a lot of ground if done correctly.
The mighty blues scale
A C blues scale has 6 notes: C Eb F F# G Bb. It’s basically a C minor pentatonic scale with an extra #4 or b5 which is the F# (or Gb of course).
The also mighty blues progression
Now lets look at the chord progression of a typical blues in C:
||:C7 |F7 |C7 |C7 |
|F7 |F7 |C7 |C7 |
|G7 |F7 |C7 |G7 :||
If we think of things diatonically (3 key changes??), the blues progression makes no sense! But when we listen to it, it doesn’t sound weird at all. There are other types of blues progression (jazz blues, minor blues etc.) but the one shown above is the most played one as far as I know.
All the chords are dominant 7th chord so we must play all Mixolydian scales to each chord e.g. C Mixolydian over C7, F Mixolydian over F7 etc. right? Nothing wrong but if we were to think that way, we are essentially losing the essence of this beautiful song form which is simplicity. Think of the key center. Since it’s a blues in C, there must be something in C we can use. Yes, the C blues scale shown earlier.
Lets compare the notes of each chord in the C blues progression to the C blues scale (C Eb F F# G Bb):
- C7 – C E G Bb
The notes from the C blues scale sound fine over a C7 chord with C, G and Bb being the chord tones hence landing on these notes are safe. Eb is an interesting note to land on too giving a more minor kind of sound.
- F7 – F A C Eb
Still an easy one to deal with as we still have 3 chord tones in our scale, C, Eb and F.
- G7 – G B D F
Only 2 chord tones here, F and G.
So now, using just one scale which is the C blues scale, we just need to be aware of the chord tones over the chord progression in the scale. It doesn’t need to be a blues scale. It can be a mixture of several scales like Mixolydian and all that. The key is to be aware of the key center which in this case, C. To me, I’d definitely stop on a chord tone or safe note over each chord but when I play some runs, that’s when things get a little wild but but but but still being aware of the key center and chords. However, always start simple first before going the complicated route! This is a crazy topic so I will write more next time.