Modal Pentatonics (lesson)

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Following David's awesome lesson of the same name (here), I thought it would be fun to delve into the theory behind Modal Pentatonics a little more, and look at a few in depth examples to help you figure them out.

Modal Pentatonics are a very different way of recycling and re-using your old pentatonic patterns in a new context to get a fresh sound without learning a lot of new scales. Although the theory behind them is a little complex if you aren't familiar with the major modes, by the end of the lesson we will have a list of rules for the use of Modal Pentatonics, so that you can work out which scales work in which context.

I recommend that you read my modes 101 lesson before tackling this - you can find it here.


A Digression: Pentatonic Modes

Modal Pentatonics, Pentatonic Modes - what's the difference? As we have previously discussed, what people usually mean by "modes" are the modes of the major scale - a list of scale variations that are derived from the major scale by moving through each degree of the scale and making it the root note. You know, Ionian, Dorian, Phrygian, Lydian, Mixolydian, Aeolian and Locrian.

Some people don't appreciate that this is just the beginning of the story of modes. In fact, any scale you care to mention (or indeed invent) has modes associated with it. They are generated in exactly the same way as with Major scales; start with the root note and call that mode 1, then cycle through generating different scales. Since the Pentatonic scale has 5 notes, it also only has 5 modes, and they don't have such fancy names as the major modes do. As with the Major modes, in the pentatonic scale, what we call the Major and Minor Pentatonic scales are in fact just modes. For the record, the Pentatonic modes are:

Image:Modal pentatonics1.jpg

As you can see, pentatonics work with some pretty strange chords because they have a sparse set of notes to choose from (The Quartal is a very strange sounding chord that has 2 4th intervals stacked on top of each other).

Now, interesting as that little digression was, it doesn't move us any closer to understanding what Modal Pentatonics are, but it may have removed a potential source of confusion!

Back to Modal Pentatonics

Ok, so what are Modal Pentatonics really? Very simply, with the correct analysis, you can figure out that it is possible to play various pentatonic scales over the different major modes to get a different take on the modes themselves, and the pentatonic scales you are using. Sounds complex? Lets look at a quick example, then delve into how we can figure this out.

Say you have a piece of music that is using a scale of G Dorian. You could solo over it using the G Dorian scale of course, but that's what they are expecting you to do! How cool would it be if you could play G, A and D pentatonic scales to give your solo a really modal feel? Well you can! Lets see how it works.

Pentatonics and Minor/Major Scales

First of all, what exactly is a pentatonic scale? As you all should know, it is a 5 note scale based on a Minor scale with notes left out. In interval terms it is:

I, bIII, IV, V, b7

or root, minor 3rd, 4th, 5th and minor 7th. Since it is based on a minor scale, it fits with no fuss over the top of one - all of the notes are compatible since the pentatonic is really a minor scale with missing notes.

In a rock context, pentatonics are often played over power chords, which lack a 3rd and hence are ambiguous as to whether they are major or minor. In this case the Pentatonic scale works well, lending a minor air to the music through its flattened 3rd.

More interestingly, the pentatonic is the mainstay of blues, and is very often played over a Major progression which gives a very dissonant sound, since in a standard blues progression 2 of the 3 chords used (the I and V chords) set up a clash between the major 3rds of the chords and the minor 3rd notes in the pentatonic scale - this is part of the effect that makes blues so fascinating.

So ignoring blues, we have so far figured out that we can play a minor pentatonic over a minor scale - no surprise really, and since the minor scale is the Aeolian mode we know that we can play a pentatonic minor in the Aeolian mode.

Modal Pentatonics Through Scales

But what about some of the other modes? Well, the quickest way is to do this by elimination - for each mode we only have to find one conflicting note and we can move on. Lets work in the basic key of C, and look at its associated modes, and compare it against a C minor pentatonic. We are looking for modes in which all the notes in the pentatonic are represented in the mode.

Image:Modal pentatonics2.jpg

So we can see that our pentatonic scale will work over 3 of the 7 major modes - Dorian, Phrygian and Aeolian.

Modal Pentatonics Through Chords

Lets look at it another way, by analysis of the chord families for the minor pentatonic and the major modes. Before you look at this, it is worth reading my lesson on chords for scales, here.

First, playing a minor pentatonic, a good fit for the notes would be the Minor 7th chord. The formula for a m7 chord is I,bIII,V,b7. Checking back to the notes in the scale above we see that all of the notes in a m7 chord are present in the pentatonic scale.

In the same way we can figure out characteristic chords for all of the modes as follows. I'll add the pentatonic in for comparison, and pick out the notes from the scale that are used to make up the chords.

Image:Modal pentatonics3.jpg

So we can see that the major modes split into 4 different chord families:

Image:Modal pentatonics4.jpg

Since the pentatonic has a characteristic minor 7th chord, that tells us straight away that we can play pentatonic with Dorian, Phrygian and Locrian, and that other modes will conflict with one or more notes in the pentatonic scale.

Modal Pentatonics In Use

Now we have figured out that pentatonics fit over 3 of our 7 modes. What can we do with this? Well this is where the fun starts.

Lets start with a piece in the key of G minor - or G Aeolian since Minor is the same thing as Aeolian. Of course we can, (and often do) improvise over a song in G minor using the G minor pentatonic scale, nothing too new here. But suppose we wanted to change the feel of the music a little and move to a Phrygian mode. Aeolian and Phrygian are similar, both minor scales, but they have a different feel to them. We can do this whilst staying with with the same chord progression providing we observe 2 rules:

1. All of the chords in our original progression were chords derived form the original scale itself in the first place - this means that all the chords in the progression must be made up from notes in our original scale (in this case G minor) - if this doesn't make sense to you, you can check out my "chords for a scale" lesson. If we don't have this restriction, all modal bets are off, and we stand just as much chance of making a horrible clash of notes as we do creating an interesting pentatonic modal journey.

2. We move to the relative Phrygian scale for our current key - what does that mean? Lets see ...

One option to move to Phrygian is to go and learn the scale of G Phrygian and use that for your solo. but you would have to change your chord progression to work with that. We have a better and more unusual option if we use our Modal Pentatonics, since we already know that we can use pentatonics over Phrygian mode. Our next task is to figure out which pentatonic scale we can use - we need to figure out what the relative Phrygian to G minor is, not just move to G Phrygian. If we use the relative Phrygian, we are still using the same notes in our scale, they will work over the same chords, and everything will drop into place.

To do this, we need to look at our list of modes and their associated mode numbers. We started with G Aeolian, which is mode VI. Phrygian is mode 3. We now need to identify the scale for which G is the 6th degree, then figure out what the 3rd degree is. One way to do this would be as follows ... remember out formula for the major scale? (TTSTTTS) Locate the 6th degree. It is in between 2 of the letters - remember the formula is really the gaps between the degrees:


Now, move backwards through the scale, one step of the formula at a time, until you get to the end. Remember that our 6th degree is G:

6 = G
5 = F
4 = Eb
3 = D
2 = C
1 = Bb

So, our base scale in modal terms is Bb, and we can now see that the 3rd degree that we need for Phrygian would be a D. This means that if we play a D minor pentatonic over our G Aeolian based progression, we will be playing in Phrygian mode - a scale of D Phrygian in fact (although with a couple of missing notes since we are basing this on a pentatonic). Don't believe me? Ok, lets check it out smile.gif
D minor pentatonic as the following notes:


D Phrygian has the notes:


What about Dorian? Easy! Dorian is the second degree, so looking at the example above, we can see that we should be using a C minor pentatonic to put us into Dorian mode.

So, we play a backing progression based on G minor, use the G, C and D minor pentatonic scales interchangeably within the solo and we will be swapping between Aeolian, Phrygian and Dorian in a very interesting way!

We can extend this to any of the other major modes, for instance, lets start playing in G Dorian. We know that G is the 2nd degree, giving our base scale as:

2 = G
1 = F

Looking at the scale of F, we get the notes:

F G A Bb C D E

We want to locate the base notes for Phrygian and Aeolian - these are A and D respectively, meaning we can use G, A and D minor pentatonics with G Dorian progressions.

And finally lets look at a mode that doesn't have any pentatonics associated with it - Locrian. It doesn't matter that we said Modal pentatonics don't work over Locrian, because we are working modally here. Even a Locrian based progression can have Dorian, Phrygian and Aeolian modal playing, and that is what we would do with our modal pentatonics. So for G Locrian:

7 = G
6 = F
5 = Eb
4 = Db
3 = C
2 = Bb
1 = Ab

So Dorian (II) is Bb, Phrygian(III) is C and Aeolian(VI) is F.

Pentatonic Scales for Modes

For the sake of completeness, here is a list of each mode in the key of G, and the 3 pentatonic scales you can use over them - reproduced from David's lesson:

G Ionian

  • A minor pentatonic (A Dorian)
  • B minor pentatonic (B Phrygian)
  • E minor pentatonic (E Aeolian)

G Dorian

  • G minor pentatonic (G Dorian)
  • A minor pentatonic (A Phrygian)
  • D minor pentatonic (D Aeolian)

G Phrygian

  • G minor pentatonic (G Phrygian)
  • C minor pentatonic (C Aeolian)
  • F minor pentatonic (F Dorian)

G Lydian

  • B minor pentatonic (B Aeolian)
  • E minor pentatonic (E Dorian)
  • F# minor pentatonic (F# Phrygian)

G Mixolydian

  • A minor pentatonic (A Aeolian)
  • D minor pentatonic (D Dorian)
  • E minor pentatonic (E Phrygian)

G Aeolian

  • G minor pentatonic (G Aeolian)
  • C minor pentatonic (C Dorian)
  • D minor pentatonic (D Phrygian)

G Locrian

  • Bb minor pentatonic (Bb Dorian)
  • C minor pentatonic (C Phrygian)
  • F minor pentatonic (F Aeolian)

The good news is that you now have the tools and concepts to figure this same list out for any key you choose!

What Are We Really Doing Here?

After all is said and done, what we are really doing here is using a familiar and easy to play scale in a different context that alters its musical function. When we play for instance an A minor pentatonic over a G Dorian chord progression, we are shifting the melody into Phrygian mode. When we play a D minor pentatonic over that same Dorian progression, we are shifting the melody into Aeolian mode. The really cool thing here is that not only are we using our familiar pentatonic scales to do this, hence we don't need to learn the patterns for all of the modes we are using, but in addition, although we are playing Dorian, Phrygian and Aeolian, we are doing so in a slightly different way and using a different palette of notes because we are using the pentatonic scale, so although we are playing the modes, they will have a fresh and different feel. This works because as we have seen, the sparseness of the pentatonic scale allows us to accommodate the different variations in the major modes because intervals that change between modes are not represented in the scale.

That's it for this lesson - questions and feedback on the forum as usual!