Calculating Parent Major Scales

View the full lesson at Calculating Parent Major Scales | JustinGuitar

Another way, along with Justin’s excellent “memorise the position” method, in helping me learn how to quickly find the PMS of the Mode I’m playing in is this:


IONIAN - 1st (or 8th/Octave if it’s easier to remember that way)
DORIAN - 7th
LYDIAN - 5th

A logical descending sequence. I’ve written these numbers in on Justin’s “All of the above” diagram, it’s just another way to help remember/work out the PMS quickly.

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Or as an alternative …

Ask yourself which degree of the scale the mode is (e.g. Mixolydian = 5) and then “reverse engineer” the corresponding root note using the Position 1 Major Scale.

e.g. To find the PMS of G Mixolydian.
Play the position 1 Major scale of (say) A Major, until your reach the 5th degree (because Mixolydian is the 5th degree). Your little finger will then be on the 7th fret of the A string which is ‘E’.
But you don’t want ‘E’ as the 5th , you want ‘G’ !
So simply slide your little finger up (or down) the 5th string until it encounters a G (which will of course happen on the 10th fret).
Then play the position 1 major scale backwards to see what Root note it will land on. In this case you will land back at ‘C’ on the bottom string,. So C is the PMS of G Mixolydian.

Actually far quicker and easier to do, than to explain ! It doesn’t require you to memorise anything, other than remembering which degree each mode is. It’s just applying simple logic to the well-known position 1 major scale.


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Here is an alternative (and I believe simple) method to find the Parent Major Scale of any major scale mode. It makes use of the circle of fifths. I have written an extensive topic on it here: Modes Part 6 - the chords associated with the modes
I will summarise with a couple of examples.

Here is a circle of fifths :

For any given major scale mode, focus only on the seven notes it contains and find them in the circle. They will always be seven adjacent notes. The tonic of the Parent Major Scale will always be the second note reading clockwise.


The C Mixolydian Mode

Use the seven-sector frame to find what we need.

The Parent Major Scale of C Mixolydian = F Major (F is the note in the second sector clockwise).

The C Lydian Mode

Use the seven-sector frame to find what we need.

The Parent Major Scale of C Lydian = G Major (G is the note in the second sector clockwise).

To explore more, check the full topics on the circle of fifths and on the modes here: Tips from the Official Guides / Approved Teachers - JustinGuitar Community

I hope that helps.
Cheers :smiley:
| Richard_close2u | JustinGuitar Official Guide, Approved Teacher & Moderator