What makes this scale very cool is the added b5 or “blue note.” The b5 adds some chromaticism to the scale, which it doesn’t have otherwise. A great sound is to really play up the chromaticism in a lick. I really love the rub and tension those notes can add to a line. If you haven’t spent some quality time with the blues scale, I suggest you do!
An A7 chord is spelled A–C#–E–G or root–3–5–b7. If we look at our minor blues scale we can see that it does not contain a very important note of the chord, the natural 3rd or C#. Although the scale sounds great, it does have some room to expand. A simple option to play over the A7 chord is the A major blues scale. This scale consists of A–B–C–C#–E–F# and its formula is root–2–b3–3–4–6. This scale now includes the natural 3rd (C#).
The real fun starts when we mix the two scales together, as we see in Fig. 1. This is called the composite blues scale. Whoa! That’s a lot of notes to think about. Here we have A–B–C–C#–D–Eb–E–F#–G, or root– 2–b3–3–4–b5–5–6–b7. That’s nine notes.
Before you get overloaded, let’s take a closer look at all the harmonic goodness going on inside here. First, we have a series of half-steps that go from B to E, and that’s where the fun lies as we can see in Fig. 2. We can use this same technique to create a classic-sounding blues turnaround, as shown in Fig. 3. To get a jazzier sound, I used all the half-steps found in this scale to create a classic bop lick with a bluesy twist as seen in Fig. 4.
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As you can see, the composite blues scale has many exciting possibilities, and I have just scratched the surface here. The thing to remember—and the key to breaking this down—is that all you are doing is mixing the major and minor blues scales, nothing more! So if you are feeling overwhelmed at the many options and sounds, start with something as simple as adding one new note to your minor blues scale. The first note I’d suggest is the natural 3rd (C#), which will put you on the right track. Remember, we can use these licks on the I chord of the blues, but be careful of that C# against the IV chord (D7)—it can really clash. What to do? Just don’t play it!
Jeff McErlain is a New York City-based guitar player, producer, songwriter, and educator. He performs regularly in NYC and abroad with his trio and blues band. Jeff has a number of instructional DVDs available at TrueFire.com, and he is a featured instructor for the National Guitar Workshop. Jeff's latest CD I'm Tired is available on iTunes or at jeffmcerlain.com.