Those of you that have played classic rock or blues based rock have no doubt jammed in a minor pentatonic over a major chord progression. In my early years I never bothered to ask why this was possible. I mean, if we're in a major key, why then can I play a minor pentatonic and it seems to sound better than the major pentatonic?
Well, let's take a look at this and see if we can come up with a decent answer.
Let's use the key of A, since it is a very popular rock key (don't be jealous E and C, you guys are popular too).
The notes of A major are - A, B, C#, D, E, F#, G#
The MAJOR pentatonic would be A, B, C#, E, F# (R, 2, 3, 5, 6 notes)
So if we're playing a classic A progression (generally a I, IV, V) we'd have a progression that goes - A, D, E.
Our major pentatonic derives it's notes directly from the major scale (duh!), but as you can see, includes the A and the E (I & V) yet not the D (IV). Our D is an important note (You could even call it Perfect!), yet it does not appear in our major pentatonic scale. Hmmmm.
Again, these notes work because they come directly from the scale, but looking at them, I don't see much of anything that creates tension.
WHAT DAVE??? You want to cause a problem??? TENSION???
HELL YEAH! That's what it's all about.
Think about life. If you had no tension in life, then you'd probably have no relief either. Maybe no reason for joy. Life would be simple and BORING. Why would you celebrate getting a promotion or winning the lotto or graduating from college (or elemenrty school for some!), if you didn't have to work at it in the first place? It seems, the more you 'sweat' at something, the bigger the reward.
In music, we like to add tension and then resolve it. Otherwise, as with life, music might seem boring.
Let's throw a bit of tension into our scale, giving us an opportunity to resolve it and make our solo much more interesting.
You could do that a number of different way, but for now, we'll do that with a minor pentatonic scale.
To create our minor pentatonic, we use notes from the minor scale of the key we are in. In the key of A, our minor scale would be -
A, B, C, D, E, F, G (R, 2, b3, 4, 5, b6, b7)
As you recall, our major pentatonic used the R, 2, 3, 5, 6 notes from the major scale. A minor pentatonic uses the R, 3, 4, 5, 7 notes from the minor sclae (or R, b3, 4, 5, b7 of the major scale).
Our example in A gives us a minor pentatonic consisting of:
A, C, D, E, G.
So again, why does this minor scale work over a major progression?For one thing, out of 5 notes, 3 of them are also included within the major scale - A, D & E. IN fact, they are the root notes of the chord progression. Pretty important notes, only two of which are included in the major pentatonic.
What about the other two notes? How do they affect our scale.
Let's look at the G first. In A major, this would be a b7 note. 7th notes play an important part in harmony. They tell us whether a chord is dominant or not. Flattening the 7th, creates a dominant chord or melody. Blues and Rock have both both used this aspect of music as almost a backbone of their sound. Flattening a 7th, does nothing to tell us whether something is major or minor. So the addition of the b7 note simply gives us a more 'bluesy' sound. It creates some tension and in many solos, is bent up to the Root.
Ok, four out of five notes work just fine so far. So what about that last one, the b3. How does that work over a major progression?
Ahhhhh, TENSION.
That's really about it. It causes tension and begs to be resolved. Playing a run in the minor pentatonic, you probably wouldn't 'hang' on this ntoes for too long. The feeling is to resolve it. Maybe to the natural thrid, which would be a 'passing' note in a minor pentatonic scale. A common blues thang, is to play the b3 then hammer onto the 3.
That's really all there is to it. As you can see, a minor pentatonic played over a major progression fits nicely as 3 of the notes come irectly from it. And the remaining two, add just the 'flavour' necessary to give your solo some feel.
Well, not quite.
Another note that can also spice things up nicely is the 'Blue' Note. A b5.
In fact, the popular Blues scale is simply a minor pentatonic with the b5 added to it. Used similarly to the b3, it adds tension and generally resolved very quickly. As a passing note.
In A, the blues scale would be:
A, C, D, Eb, E, G
Likewise, this plays nicely over a major progression. For a real nice sound, play 7th chords A7, D7, E7 or varieties of them. Also, throw in some other extended chords (9th, 13th).
Hope you got something out of this.