Music Theory 402 - The Blues

Blues music is a true American creation. It is non-diatonic in its harmonic structure, but it sounds so good to us because we have heard it all of our lives and there are musicians who really do a fantastic job with it. These players had a great ear for what they wanted and a great sense of rhythm and phrasing. Blues has always been more about feeling than anything else. Therefore, it is not surprising that the dominant 7th chord is the predominant chord in blues music.

As we have already learned, the dominant 7th chord is the strongest chord in music. It creates the most obvious pull towards resolution. This chord contains both a major triad and a diminished triad so it can therefore be viewed as containing both major and minor sounds. But in diatonic harmony, the dominant 7th chord only exists in one place: the V chord.

Of course, these early players knew nothing about formal music theory. They simply knew what they heard. And what they wanted to hear was a progression made up entirely of dominant 7th chords. Period. That's how it started. Instead of having three major chords in a I IV V, or their corresponding diatonic 7th chords, they loved the sound of the dominant 7th so much that they made all three dominant. ie: I7 IV7 V7.

The chord's quality is such that it can express a sad connotation as well as a happy one. And when you look at the blues progression as a whole, you find that it lends itself to both major and minor sounds. Because we have left diatonic harmony, there are multiple approaches to playing over the progression. Let's break them down.

• The first approach is to view the progression in one key and find pentatonic scales that work over all three chords.
• The second approach is to view each chord as being in it's own key. This means that each chord will imply a specific scale to be played.
• The third approach is to think linearly and go by sound. Follow your ear so to speak. Like a voice.

Let's try the first approach. What scale will work over all three chords?  A blues in C, for example, will contain C7, F7, and G7. If we look at this progression from a key centered approach, we will find that there is a problem with our 3rds and 7ths between specifc chords. When we see C7, we know we have a major 3rd (E) and a minor 7(Bb). When we switch to our IV chord, F7, notice that the b7 in F7 is Eb. Not E. Obviously, if our key center is C, then E is a major third and Eb is a minor third. How can we have a scale that is playable over major and minor chord sounds? WELCOME TO NON-DIATONIC HARMONY.

If we lay out the chord tones for our C7, F7, and G7 chords we are left with the folowing notes:

C D Eb E F G A Bb B  or 1 2 b3 3 4 5 6 b7 7 (scale degrees as they relate to the tonic C)

What on earth do we do with that?

Here's the deal: there is no one scale. There can't be. And that's good! But, there is a super basic approach that invovles pentatonic scales that many players have gone to the heights of fame utilizing. Think B.B. King, Albert King, SRV, etc. Usually it works like this: Either play the minor pentatonic scale of your key center (C minor penta in this case) over the whole progression (a la Albert King), use the major pentatonic scale of your key center (C major Penta) over the whole progression (a la B.B. King), or mix and match (a la SRV). 

I know this is an over-simplification, but if you mix and match, it is of little debate that when playing in a key centered approach, the V chord sounds best with major pentatonic,and the I and IV chords sounds best with a minor pentatonic approach (to take advantage of the b3 we talked about earlier). Try the slow blues jam tracks below and give it a whirl.  There are different blues scales that we will learn, but for right now stick with the basic pentatonics.

Now for the second approach - viewing each dominant chord as a V chord in it's own key. This will obviously sound much more modal than the previous approach. Think Robben Ford or Larry Carlton. This approach is essentially the gateway to jazz: the idea that each chord can, if desired, be its own world, or, its own moment in time. Usually - and I use that lightly - tempo dictates how far "out" a player will go.

The obvious choice with this approach is to think I Mixolydian, IV Mixolydian, and V Mixolydian. You can choose to play our applicable modal triad approaches, pentatonic approaches, arpeggio approaches, and three note per string approaches as we discussed in our diatonic harmony lessons. You literally assume each chord reflects a new key center, and you spell it out like you mean it. You sell it. Almost try to make people forget about I7 when you go to IV7. V7 will always imply a root movement to I, and all the more reason to make that tension require resolution. There really isn't much more to say about this approach that we haven't already said in our diatonic chapters. Just view each chord in the progression as it's own key and think diatonically.

The last option is to link linerally. To think like a voice. To think rather irrespective to music theory, if you will. This is obviously a combination of the above two approaches. If a note is heard in one's head... play it. If it sounds good... maybe you figure it out theory wise, maybe you don't. This is how the blues singers did it. You want to go up? Go up. Go down? Go down. Just listen.

What will happen is you will find that the most emotional players never stick to a specifc tonal approach. The theory is almost realized in hindsight. The same song will, almost always, be played differently every night. And that's the point. SRV is a perfect example. He mixes and matches pentatonics, modes, arpeggios, and just straight up singing, soaring bends, slurs, and slides. When you have practiced it from both a key center approach and a chord scale approach, and are comfortable with both, then the ultimate goal is to be able to combine the two approaches; to develop your taste; to develop your style; to appreciate that there is no single, or right way to do it. Respect others interpretation of the progression. Make them respect yours.

One more thing: There is also a minor blues. The minor blues contains a minor I and IV chord but with a V7. The I and IV chords can be played as mi7 chords as well as triads. We will get into this in detail later, but the same principles apply when soloing over this progression. Think "the thrill is gone."

Jamtracks:

1.  Slow Blues in A - I7 - IV7 - V7

2.  Slow Blues in G - I7 - IV7 - V7

3.  Bb Minor Blues - Imi7 - IVmi7 - V7