The Blues Scale

When you add the tritone (flatted fifth) to the A minor pentatonic you get the A blues scale: a c d d# e g.  The is the basic blues scale.  There are some extended blues scales I’ll mention in a minute, but let’s not get ahead of ourselves.

You use this A blues scale when your guitarist buddy is playing blues in A.  Easy.  A typical blues chord progression in A might be:   A7 / / /  D7 / A7 /  E7 D7 A7 / .  (In this simple 12 bar blues a slash means stay on the same chord for another bar.)  You would solo using notes from the A blues scale: a c d d# e g.

I can hear you objecting, “A7 is based on A major, but the A blues scale is based on A minor.  You can’t play A major and A minor together!   Didn’t you just tell me that what makes the pentatonic work is that it uses notes good for all the chords in the scale?”  Excellent point.  I’m glad you’re paying attention.  But get over it.  In blues this is how it works.

On one level blues is about this clash between major and minor.  The accompaniment is major, in this case all dominant seventh chords in the key of A major.  But the lead, be it vocal or lead guitar or you on keys uses the A blues scale, which is based on A minor pentatonic, a minor scale.  That minor lead over major chords is one thing that gives the blues its characteristic sound.

It’s fun to play the blues scale over a blues progression, and while it works pretty well for vocals and lead guitar, after a while it doesn’t sound totally right for lead keyboards. If you want to play blues and boogie woogie piano convincingly you’ll need to learn some blues riffs too.  Those don’t generally fit into the pentatonic scale, so I’m not going to mention them further here.  

There are extended blues scales that keyboard players use for jazz and blues.  Since our subject is pentatonic and related scales, I’ll mention an extended blues scale which combines the basic blues scale with the major pentatonic.  For example,  C extended blues scale is nine notes, using notes from both C blues and C major pentatonic: c d d# e f f# g a Bb.   B natural may get added to the scale, making it a 10 note scale which is formed from the union of the major scale and the simple blues scale.  I’m not going to say anything else about extended blues scales in this essay.

Next: The Bluesy Scale