RECAP

In the previous topic, we have listed several modes and for convenience we have related them to the major and minor scales.

Specifying the intervals with respect to the starting note we had:

Ionian	1	2	3	4	5	6	7
Dorian	1	2	b3	4	5	6	b7
Phrygian	1	b2	b3	4	5	b6	b7
Lydian	1	2	3	#4	5	6	7
Mixolydian	1	2	3	4	5	6	b7
Aeolian	1	2	b3	4	5	b6	b7
Locrian	1	b2	b3	4	b5	b6	b7

The table above defines each degree of the modes as an interval with respect to the starting note.  Comparing each mode with the Ionian mode, you can easily determine what you need to do to obtain any other mode.  In order to transform the Ionian mode into the Dorian mode (for example), you need to lower the 3rd and the 7th of the Ionian scale. Raising the 4th would transform it into a Lydian scale. And so on and so forth.

For example, let’s find the A Mixolydian scale:

•      We start from A major: A  B  C#  D  E  F#  G#  (A)

•      We apply the Mixolydian pattern, meaning we lower the 7^th; the result is A  B  C#  D  E  F#  G  (A)

Of course, you can also work out the Mixolydian mode by remembering that it is a major scale started from the fifth degree; the major scale whose fifth degree is A is D major, i.e. A B C# D E F# G; starting that scale from A gives us A B C# D E F# G as above.

It is a good idea to memorise this information or keep the chart handy, as we will need it further on.

B Choosing appropriate modes

If there is no chord progression (i.e. there is only one chord over a long series of bars) the mode is implied (we will come to that later).

If there is a chord progression, there will usually be a tonal centre towards which the progression moves (although this is not always the case). The first and most important thing to do is to identify that tonal centre. This will give you the resolution chord (I chord). Identifying the tonal centre can be difficult, so here are a few strategies to help you along:

•       the last chord is usually the resolution chord;

•       the first chord is often (but not always) the resolution chord;

•       identify recognisable cadences (such as ii-V-I or I-IV-I);

•       watch the movements of the roots of the chords - they often imply typical cadences;

•       use your ears!!

1. Four Notes Chords

Take the following simple progression:

Cmaj7 - - - / F - - - / C - - -

This looks (and sounds) like a I - IV - I progression in C major (i.e. the tonal centre here is clearly C).  Let's write down the constituent notes of these chords as we find them:

Cmaj7:             C-E-G-B

F:                     F-A-C

Sorting these notes in ascending pitch order gives us:

               C         ?          E          F          G         A         B         (C)

or written in intervals

            1         ?          3          4          5          6          7          (8)

We still have an "unknown" second degree, which is not directly imposed by the harmony; but looking at the reference chart above, we find that the only mode that accommodates our case is the Ionian mode:

               C          D         E          F          G         A         B         (C)

            1          2          3          4          5          6          7          (8)

You can play any of these notes in any order over any of the chords of the progression: that will have no impact on the mode of the song. (But please remember that the best melodic result will usually be obtained whit characteristic notes on the downbeats – see Intermediate Theory tutorial).

2. Triads

The chord progression above contained a maj7 chord; what if it didn't? Say the progression was:

C - - - / F - - - / C - - -

Writing down the notes as they are imposed to us by the chords being used, we find:

C:        C-E-G

F:         F-A-C

This results in the following scale:

               C         ?          E          F          G         A         ?          (C)

               1         ?          3          4          5          6          ?          (8)

Now we have two "unknowns" (two notes that are not imposed by the harmony) and from the reference chart we see that we can choose to play a B note or a Bb note.  Depending on that choice we will end up playing the Ionian mode or the Mixolydian mode.  The tonal centre is still strictly defined (C), but the mode is less strictly defined than in the previous case.  Since the chords don’t impose the mode, you as the lead are free to pick the one you want.

(In fact, you may want to be careful if you play C Mixolydian, because a Bb in a C chord makes it

C7, which is the V7 of F, so you could very easily cause a transposition into the F key!)

In general, very rich harmonies define modes much more strongly than “lighter” harmonies. In the first example above, we had a Cmaj7 implying a B note; in the second example, we had a plain C; that left some more room.

3. Power Chords

If the harmonic background consists of power chords (R + 5th + R), no thirds are played. Consequently, the harmonic content of the song is much less strongly defined, and you, the lead player, have a big responsibility in determining that content and the resulting color.

Power chords also usually imply a tonal centre, but it is often suggested more than it is imposed.

Let's take a simple example to start with. Suppose we have the following progression: E5 - - - / C5 - - - / D5 - - - / B5 - - - / E5

The question is: which mode(s) are you going to use to improvise?

In this case, the progression "sounds" like it resolves into E5. This assumption is supported primarily by the final bass movement B - E which strongly establishes E as the tonal centre (since it suggests a V – I cadence). Therefore, some sort of E scale will do for our solo. But which one exactly?

Let's write down the E major scale: 

               E          F#         G#    A           B         C#         D#    (E)

            1          2          3          4          5          6          7          (8)

Now let's write down the notes implied by each power chord in the actual progression, and place them at their proper location in the E scale:

E5:	E	?	?	?	B	?	?	E
C5:	E	?	G	?	B	C	?	E
D5:	E	?	G	A	B	C	D	E
B5:	E	F#	G	A	B	C	D	E

Compared with the major scale (Ionian mode), we actually have:

               1          2          b3        4          5          b6        b7        8

This is the signature of the Aeolian mode. E Aeolian is therefore the theoretically correct scale for this progression.

For contrast, here is another example:

E5 - - - / A5 - - - / B5 - - - / E5 - - -

For the same reason as above, the tonal centre is E. Let's work out the scale as above.

E5:       E         ?	?	?	B	?	?	E
A5:       E         ?	?	A	B	?	?	E
B5:       E          F#   The signature is	?	A	B	?	?	E
1          2	?	4	5	?	?

with three undefined intervals. Therefore all the following modes of E major will fit this progression:

•      E Ionian:	1 2 3 4 5 6 7
•      E Dorian:	1 2 b3 4 5 6 b7 (equivalent to D major)
•      E Mixolydian:	1 2 3 4 5 6 b7 (equivalent to A major)
•      E Aeolian:	1 2 b3 4 5 b6 b7 (equivalent to G major)

So you can use any one of them (or all of them), depending on

•       how you "hear" the progression (rather minor or rather major)

•       what the rest of the band is currently playing

•       the overall context of the song

All the examples above assume that there is only one tonal centre. Of course this isn't always the case. Suppose we have the following triad progression: E - - - / C - - - / D - - - / B7 - - - / E 

Working out the notes as above reveals some conflicts:

•       G# in the E chord conflicts with G in the C chord

•       D# in the B7 chord conflicts with D (root of the D chord)

So, what do we do?

•       One possibility is to adapt to the changing tonal centers, and develop a chord oriented solo.  For example, you could play a C and D arpeggio on the corresponding chords 

•       Another possibility could be to treat the first three chords (E, C and D) as an A melodic minor sequence, modulating into E major (more on modulation later on)

•       Or you could use pentatonic scales; for example, it is possible in this case to play E pentatonic minor throughout (please verify this!)

4. Vamps

A final interesting case is when the band keeps on repeating the same chord for a long period of time (this is called a "vamp").  Depending on the type of that chord, you may have a lot of freedom or no freedom at all in choosing the mode.  

Power Chord

Since all the modes of the major scale accommodate a given power chord (except the Locrian mode which has a b5 and would conflict with the 5 of the power chord), the lead can vary modes and colors at will. This is in fact what Joe Satriani calls his “pich axis” theory.

Triad or Seven-Note Chord

If the chord is a triad or a seven note chord (or more complex chord), the mode is implied.

The lead has little or no freedom at all.

To understand why the lead has no options in the second case above, we need to revisit the relationship between chords and scales.  Let’s take a C major chord: its constituent notes are (C E G).  A Cmaj7 chord would contain (C E G B); a Cmaj7(9) contains (C E G B D), etc.  Starting with the latter chord, we can continue to enrich it by adding more thirds; the most complex C chord we can make this way is (C E G B D F A).  Map back all these notes within the boundaries of an octave, sort them by ascending pitch order, and you end up with:

C             D           E          F          G          A          B

In other words, the C major chord is a shortcut of the C major scale, or Ionian mode; the richer the chord becomes, the better it approximates the corresponding scale/mode.

Similarly, starting with a Dm chord and stacking up thirds you obtain (D F A C E G B), or

D            E           F          G          A          B          C          D

This is a D Dorian scale.

If you do this for all the degrees of the major scale, you will find out that:

•      The Ionian mode corresponds to the I chord

•      The Dorian mode corresponds to the ii chord

•      The Phrygian mode corresponds to the iii chord

•      The Lydian mode corresponds to the IV chord

•      The Mixolydian mode corresponds to the V chord

•      The Aeolian mode corresponds to the vi chord

•      The Locrian mode corresponds to the vii chord