You probably know at least your first pentatonic shape, no matter what level you're at. If for any reason you don't, here it is:
The highlighted notes are the root note ( in this case A ). You'll notice that the pentatonic is a five note scale only, and the notes are merely repeated over two octaves ( and then one extra note is added on top to make the pattern a two-note per string pattern ).
Let's get into a little bit of theory here. Don't worry you only have to know how to count to 7 in order to understand what I'll be explaining, so most of you should be just fine.
Here's the diagram for an A natural minor scale over a single octave. While you practice it, make the habit of counting out each note. The first note should be 1 and the last one should be.... 1 as well. You should count backwards when coming back down.
Now, try counting the following over the next diagram : 1, 3, 4, 5, 7, 1.
You might have found that the notes line up at the exact same places in the two scales. In essence a minor pentatonic is a simplified natural minor scale, where the second and sixth note are removed. If you have no idea what modes are, then just take this for granted for now: the natural minor scale is actually a mode, it's the sixth mode based off the major scale and is called the aeolian mode. So if you know your pentatonic scale shape and where each degree is located, how hard is it to add a couple of extra notes in between the existing ones?
Pretty easy right? You only have to know which notes to add and for that you need to know the scale or mode formula and pick the notes that are missing from the pentatonic scale, in this case, the 2nd and 6th.
Here's a diagram that shows where they're located on a single octave pattern By only adding those two notes, you effectively re-create the natural minor scale ( AKA. the aeolian mode ). All you have to do is find the octaves of those notes to insert in the rest of the pattern to have a 6 string pattern of aeolian mode based off a pentatonic pattern.
One thing to keep in mind is that you don't actually need to play all the notes in the mode in each and every octave of the scale to sound like you're playing a mode. So in essence what you should do is stick as closely as possible to the original pentatonic shape and only add notes that fit inside the shape and don't make you go too far away.
For example, I'd rather use this shape than a more complete one that would make me reach for notes outside of the original pentatonic shape.
You'll notice that I've only added the 6th degree ( actually the minor 6th but that's not relevant at this point, we'll get back to this later in this series of articles ).
Make a recording of an Am vamp with anything you have at you disposal and try all 3 shapes ( natural minor/aeolian, minor pentatonic, and minor pentatonic with the minor 6th added ) and you'll find that the missing degree on the last of these doesn't make a HUGE difference. It only makes the scale sound that much closer to a mode than a pentatonic scale. And that's exactly the effect we're looking for here: having the modal sound come out of a pentatonic based shape.
If you want to get even closer to the original mode, you can learn this diagram that adds the 2nd degree as well.
You could add the 2nd degree by playing the note located at the 9th fret of the D string, but it would defeat the purpose of sticking to the pentatonic shape as much as possible.
So by now you should realize that modes can be created in at least 2 different ways, the most common being by seeing them as scale inversions ( which they really are ), or seeing them as scale alterations ( which serves our purpose of simplifying their usage ).
In the next installment, we'll go over the major scale and we'll discover a little secret that will unlock the mysteries of modal playing for ever. Stay Tuned.
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