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The Pentatonic Scale

I hope that you understood our systematic approach to the diatonic scale in the last chapter.

Now I would like to move on to the pentatonic scale which is basically nothing but a subset of the diatonic scale. As the name "penta" (five) tells you, this scale consists only of five notes instead of the seven notes of the diatonic scale.

Most of you might associate the pentatonic scale mainly with the Blues but it goes also well with other musical styles.

Why use only 5 notes out of 7? Basically the answer is: it gives you more flexibility when improvising over complicated chord changes and thus less likelihood of hitting a wrong note. However, you don't have to limit yourself to the pentatonic scale, since you can always switch back and forth between 5 and 7 note scales based on the mood of a tune or the actual chord changes. 

There is only one diatonic scale in a given key, but there is actually three pentatonic scales that are its children.

Here they are in the key of C major (the minor and major label refers to the different roots of otherwise identical scales):

The A minor or C major pentatonic scale

The D minor or F major pentatonic scale

The E minor or G major pentatonic scale

Now if you look at our pretty familiar C major Scale you will appreciate the fact that all 3 pentatonic scales are just subsets of the diatonic scale:

The good message is that you don't have to learn 3 different pentatonic scales but only one and then shift it to different starting points.

As with the diatonic scale there is self-repeating patterns (as 7-note patterns repeat themselves after every 7th string, 5-note patterns do the same thing after every 5th string). So don't just memorize the whole fretboard or the 5 commonly taught pentatonic postitions without recognizing these patterns.
What I suggest is to learn them as subset of the diatonic scale. So basically take the 6-note patterns that we have discussed in the chapter about the diatonic scale and transform them to pentatonic 4-note patterns based on your needs. You will by now know how to do it...

Now for practical playing: when do you use what pentatonic scale?

There is some very simple rules: you can play the A minor or C major pentatonic scale over all diatonic chords derived from a C major scale apart from a G or G7 chord (lazy guitarist approach) because there is no notes clashing with these chord tones. So most folks use mainly the A-minor pentatonic scale since it is the most "user-friendly", but there is a problem associated with this: after a while playing a melody with only 5 notes gets kind of boring. So you should definetely use the other pentatonic scales, too, to spice up your playing. However, you have to be more careful with the other two scales because some notes don't go too well with the chord notes.
This is what has been called "avoid notes". However, they don't have to be avoided at all cost, rather handled with care. Most of the "avoid notes" correspond to the fourth of a major chord clashing with the major third. But try it out and decide for yourself. This is a hands-on tutorial!

The rule for the other two scales is that they should best be played over the chords that they are related to. So generally speaking, a D minor or F major pentatonic scale goes well with D minor and F major chords and the same is true for the E minor or G major pentatonic scale.

Here is a table that summarizes possible chord/scale choices in the key of C major (for simplicity I have just listed the minor scales):
Chord Possible Pentatonic Scales"Avoid note"
C majorA minor, E minorF
D minorA minor, D minor, E minornone
E minorA minor, E minorF
F majorA minor, D minorB
G majorE minorC
A minorA minor, E minornone

So we learned about the first pentatonic scale application: omitting "avoid notes" that would otherwise clash with chord tones. Because simply playing a diatonic scale over diatonic chords does not necessarily sound good. Limiting your choice of notes is sometimes better and will produce more tasteful melodies (as long as you make the right choices). So the pentatonic scales can simply be regarded as a very good compromise between strict chord tone arpeggios (that sound too boring) and the full diatonic scale (that may sound too dissonant).

The Blues

While almost everybody plays the Blues and seems to know what it is like, the theoretical background is a bit more complicated than generally believed. The Blues is a music style that came about as a mixture of Western and African musical traditions.

There is no single harmony theory that could sufficiently explain why the Blues is what it is. In fact although people might think that the Blues is a pretty simple matter, its actual form is harmonically complex.

In typical Western harmony there is only one dominant 7th chord within one key (e.g. G7 in the key of C major). However in a typical Blues there is three dominant 7th chords, e.g. D7, G7 and A7! If you wanted to construct 3 dominant 7th chords within a Western music theory framework, you had to borrow them from three different keys: G major (D7), C major (G7) and D major (A7).
By doing so, you would end up getting some sort of tritonality where minor and major harmony are present at the same time. And this is essentially what the Blues is all about: you can play minor and major scales over major 7th harmonies at the same time. Typically however, a minor pentatonic scale is played over major chords.

While completely out of touch with classical music theory of the so called "common practice period", our ears have learned to appreciate a certain "bluesy" sound that is associated with this clash of major and minor harmony.

It is also very important to realize that along these lines there is two completely different feels when it comes to interpreting a tune, either "classical" or "bluesy". This has a lot of important implications for musical practice. It does not matter wether you are a Heavy Metal or a Jazz guitarist. You always have the choice of how to improvise on a tune. It completely changes your choice of notes. However, some guitarists like Ritchie Blackmore were also masters of uniting these two normally strictly separated worlds.

I will give you a practical example of Blues harmony and note choice. Let's assume that we have a Blues consisting of the following harmonies: D7, G7, A7.
Now let's improvise over these changes.  Within a Western musical theory framework what you would normaly do is you would use Mixolydian scales over all three chords. Since according to the classical theory this is 3 distinct keys, you would use D Mixolydian, G Myxolydian and A Myxolydian. This sounds Ok, but is not very bluesy.  
So to sound bluesy you would make use of the clash of major and minor harmonies. Converting the major third of the Mixolydian scale to a minor third results in a Dorian scale. Dorian is actually a pretty cool-sounding scale and is used a lot in Jazz. It might however sound a bit too "jazzy" in such a simple Blues progression - but try it out, this tutorial is about experimenting.
So basically, what we do is use a minor pentatonic scale derived from a Dorian scale (but you can throw in some Dorian extensions every now and then based on your personal taste).

So a D Dorian-derived pentatonic scale over D7 means that we are actually now in the key of C major (as opposed to when we interpreted this chord very classically and played a D Mixolydian scale which corresponds to the key of G major). So harmonically this "bluesy" approach is completely different!

Let's take a look at the D Dorian scale and the derived D pentatonic scale:

Here is the D Dorian scale:

Surprise, surprise, this is actually identical to our good old friend the C major scale that we know pretty well by now!

And here is the D Dorian derived minor pentatonic scale that we used to improvise over the D7 chord:

Does this look familiar? Sure, it is just the D minor or F major pentatonic scale that we discussed above!

So the harmonic context is different (we are playing this scale over a dominant 7th chord as opposed to playing it over a D minor or F major (without minor 7th!) chord in the above example but the scales are exactly the same. It is very important that you understand this difference!

Now what about the rest of the Blues progression?
There is also a simple rule of what minor pentatonic scales go well with dominant 7th chords of a Blues progression (using the above example):
Chord Pentatonic Scale
D7D minor
G7D minor, G minor
A7D minor, A minor
As you can see the "lazy guitarist" approach would be to use the D minor pentatonic scale throughout the whole Blues (probably only topped by staying in just one position!). However, since you have decided to read a tutorial that promised you to open up the whole fretboard for you, you are probably thinking that this is not a very good idea!
You are absolutely right - experiment with the other pentatonic scales and you will achieve a much more pleasing sound! To spice it up even more, throw in some tiny doses of D Dorian extensions (the two notes that are lacking in the D pentatonic scale)......