Most blues guitarists use a simple variety of scales. While most of them likely learned from emulating their favorites, they may consider their playing as being derived from a scale, its just what they play. Its worth noting that that the minor pentatonic scale and the blues scale are often called upon by guitarists to give them the blues sound that they desire.
In this article we’ll be talking about the theory and construction of both the minor pentatonic and the blues scale. By understanding some of the theory, you can start to piece together some good places to employ either of these scales and how to vary them as you play.
The Pentatonic Scale
The pentatonic scale is a five note scale noted not only for its simplicity, but for its ease of deployment in musical situations. Lacking some of the extraneous notes, the pentatonic scale tends to fit nicely over a variety of chord changes with minimal fuss. The pentatonic flavor we shall focus on is the minor pentatonic.
The minor pentatonic is a stack of five notes. Starting with the root, a minor third is stacked upon that. After the minor third, a standard fourth is added. After the fourth, a standard fifth is appended. And finally the minor seventh, or flatted seventh is added. In the end you get these handy intervals:
- Minor Third
- Minor Seventh
It’s worth noting that these intervals are also the basis of the blues scale. The minor pentatonic is great for using over any chord progression that resides in a minor key. An easy way to tell if a chord progression is minor is to look for the minor chord in a progression, especially if it is the first chord. This will tell you which minor key to use. An A Minor chord means you should probably use the A minor pentatonic scale.
The Blues Scale
Now that you’ve seen how simple the minor pentatonic scale is, we’re going to effectively add another note and turn that minor pentatonic scale into a blues scale. We’ll do that by adding a flat fifth in addition to the other five notes. The intervals in a blues scale are shown below:
- Flatted Third (blue note)
- Flatted Fifth (blue note)
- Flatted Seventh (blue note)
You’ll notice that I also tagged some of the notes as blue notes. That is because they are often contrasting against the major tonality of the chords in a standard twelve bar blues progression. The great thing about this is that the ‘blueness’ of the scale is built into the relationship of the blues progression and the scale.
As you move to the IV and V chords in the blues progression, the flatted seventh of the blues scale becomes the fourth and the minor third of the chords, respectively. These relationships mean that you can keep wailing on a single blues scale for the entirety of a blues progression. In my opinion, this help keep you in ‘the zone’. You don’t have to worry about chord changes, you just have to play your heart out.
Now that you’ve got a little taste of some of the theory behind it, go out and play this stuff!