Blues Guitar Theory

Blues and blues-based rock songs break away from traditional guitar theory by apply the minor pentatonic scale over a major based chord. Specifically, this occurs over a dominant seven chord (written as simply 7), or at least a chord functioning as a dominant seven. The only chord in a key that produces a dominant seventh is V (5). This is because the fifth scale degree is a major triad, and it has a flat 7th interval. Mixolydian Mode stems from the fifth degree.

Blues Guitar Scales

Playing the minor pentatonic scale over a major based chord produces the follow intervals:

Root, b3, 4, 5, b7 (and possibly the b5 ala the "blues scale.")

So you nearly have all the intervals necessary to build a dominant seven chord, minus the major third. Playing a minor third over a major third produces some dissonance, but in a blues-based context this clash of notes creates an edgy sound that we've grown to like (it's called rock 'n' roll). Often times players will also add in the major third to minor pentatonic scale patterns, or use a combination of both major and minor pentatonic (which is actually combining two different keys).

So, blues-based rock songs can include Mixolydian Mode (a.k.a. the Dominant scale) and/or minor pentatonic. And you don't always have to break the rules. Blues-based players also use the major pentatonic scale over major chords as traditional guitar theory would normally teach.When you combine all these scale choices you end up with lots of notes to include in your melodies, riffs and lead guitar solos.


Play Until Your Fingers Bleed!

Mr. Desi Serna (Google Me!)

Author of Fretboard Theory


http://www.Guitar-Music-Theory.com

Scales, Chords, Progressions, Modes