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Pitch Axis theory and the Modal Method I: The simple concept

For those of you unaware of the details of pitch axis theory, the idea is basically to connect scales or their modes via an unchanging, or changing as little as possible, bass note. Used by classical composers such as Wagner and Stravinsky as well as modern guitarists like Joe Satriani and Steve Vai, it is a useful tool. But is it just another name for a technique that has been used before?

The first track on his first album, Not of this Earth, demonstrates Satriani’s use of pitch axis theory perfectly, a pedal note of E, and four bars with a change of mode on each:

E Lydian – E Aeolian – E Lydian – E Mixolydian

Now, another way of putting it is that Satch is playing in the following keys but staying on the same bass note:

B Major – G Major – B Major – A Major.

Now we can see the interesting idea behind the sound of the modes, a large leap from B Major (5 sharps) to G Major (1 sharp), back again and then back twice in the circle of fifths to A Major (3 sharps).

It is quite an art form, choosing modes that suit the following or preceding of another, but we can see now the pattern:

Lydian – Aeolian – Lydian – Mixolydian

Now, none of this is new, there are plenty of instances where J. S. Bach uses multiple modes over the same bass note, notably over a bass that is acting as a dominant pedal.

Here is an example:

Mixolydian – Phrygian Major – Harmonic Major – Dominant #2 – Double Harmonic

The example above is played over a constant bass pedal, say A. That gives us the scales:

D Major – D Harmonic minor – A Harmonic Major – D Harmonic Major – D Hungarian minor

This sequence is typical of Bach as he has created a symmetrical sequence, with scales on D, D, A, D, D.

The Modal Method can help to take this concept one stage further. Say over a constant A bass I play the scales from the sequence:

G Major – A Melodic – E harmonic minor – B Neapolitan Major – A Neapolitan Major – E Locrian natural 7 (which is one of my favourite sequences). We get the modes in pitch axis theory of:

A Dorian – A Melodic – A Dorian #4 – A# Altbb3 – A Neapolitan Major – A Phrygian #4

I have simply used the sequence of scales that I have worked out using the tables in section I and played them over a static bass note. It’s that simple. NB: Although the A# in the Altbb3 mode clashes against the A bass note, it is consonant enough if resolved quickly and adds a good tension to the sequence.

I intend to add pitch axis examples as and when they come up and make a comprehensive list, so please add your ideas below in the comments. Here is a Steve Vai one, The Riddle:

E Lydian – E Lydian + - E Mixolydian – E Lydian

The scales are: B Major – B Melodic – A Major – B Major

Such a nice effect with the Lydian + mode, love it.

So now we have:

1) Not of the Earth: Lydian – Aeolian – Lydian – Mixolydian (Satriani)

2) The Riddle: Lydian – Lydian + - Mixolydian – Lydian (Vai)

I cover the 462 modes of all of the 66 seven note scales in my book available here:

Thanks for reading.

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