Blues Theory

[higgi]

Most blues songs are I7 IV7 V7 right? Mostly major with flated 7ths? When do you use the blues scale with the minor third? The guitar hooks are usually minor third but the bass walks sound major.

[RiddimKing]

From a bassist's perspective, one way of looking at a major blues is to think of it as a Mixolydian scale that modulates from the I to the IV to the V. In other words, your scale pattern is 24, 124, 124, 134 with the first '2' moving to the root of the chord you're playing. You'll have the dominant 7 in each scale, but not the flat 3. You generally use the blues scale for soloing. I'm not smart enough to know why this is true...

[JimmyM]

You don't have to be smart to know why...it just plain sounds good. That's why they do it.

[higgi]

Thanks guys. So just play the major scale with a flat 7 for that chord unless soloing? That's what I have been doing sorta, but I just wondered about when the Guitarest and I would end up on the third at the same time.

[middy]

The guitar (and other melodic instruments) often play the minor third and the major third. That's just the blues sound. In fact, when I play blues guitar the only notes I usually don't play are the minor second, the minor sixth, and the major seventh. But, sometimes the minor sixth is used when leading into the IV (the minor sixth of the I is the minor third of the IV), and the major seventh and minor second are sometimes used as passing tones.

There are no rules in blues, as long as it sounds right.

[Deacon_Blues]

I have never before really tried to figure out why you use the minor 3rd in the blues scale in soloing and melody when the key is major, I just always thought it sounds good. One possible reason is that the minor 3rd also can be considered as a sharped 9th which sounds good on top of the I7 and V7 chords (e.g. E7#9). The same minor 3rd/sharped 9 is also the dominant 7th on the IV7 chord. That, too, might have something to do with the note fitting in so well...

I once heard a guitarist playing "Hound Dog" using minor chords instead of major. Needless to say, it sounded terrible, but I can understand him - He was a singer/guitarist () and the melody is always on the minor 3rd, not the major. If he would have tried playing a walking bass line over the song, I guess he'd have noticed his mistake...