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Tuesday, November 6, 2018

Modal Short Cuts

Assuming I know major and minor scales, I need to learn five other modes.

Mixolydian and Lydian are have a major third, so those I can associate with major scale.

Mixolydian is simply the scale of the dominant 5th, so I already know it. I'd put a Bb instead of B in C major.

Lydian has an augmented fourth, with the rest of the notes like the major scale.



The other three modes are minor in tonality.

Dorian is a minor scale, but without the flatted sixth. I can associate it with the ii of a ii-V-I progression, then.

Phrygian is a minor scale with the addition of a flat 2.

So those two modes each differ only one note from the minor scale.



Locrian has the flat second of the Phrgian, a minor third, a diminished fifth, and flat 6 and 7. So take a Phrygian and flat the fifth. Or flat every note except the fourth.



So, from the circle of fifths, G and F yield modes only one note different from C major.
[G and F major have one accidental in their key signature]

D Dorian yields a mode two notes different (flat 3 and 7)
[D major has two sharps]

A minor (Aeolian) has three notes different (flat 3, 7, 6)
[A major has 3 sharps]

E Phrygian has four notes different (flat 3, 7, 6, 2)
[E major has four sharps]

B Locrian has five notes different (flat 3, 7, 6, 2, 5).
[B major has five sharps].








4 comments:

Vance Maverick said...

Or, in order of increasing flatness, illustrated with C scales and standard key signatures:

Lydian: one sharp (=G)
Ionian: no flats or sharps (=C)
Mixolydian: one flat (=F)
Dorian: two flats (=Bb or Gm)
Aeolian: three flats (=Eb or Cm)
Phrygian: four flats (=Ab or Fm)
Locrian: five flats (=Db or Bbm)

Locrian is not really in use -- it was invented (whenever this system of modes was re-codified -- 19thC?) just because it's the next step in the system, like an unstable element in the periodic table that exists only in the cyclotron.

The next step would be six flats -- but note that as in Gb major, that would include C-flat, meaning the tonic would be lowered -- and we're back at Lydian again, one half-step lower than we started.

In this light, the modes are not just a set but a cycle.

Jonathan said...

I was working that out in insomnia last night. I figured Ab would give Phrygian in C because you can start on C and play all flats of Ab major. C-Db-Eb-F-G-Ab-Bb-C. I already knew C minor is relative minor to Eb, so I didn't have to figure that out again. Locrian, which as you say isn't really used much, starts on C and adds that unstable diminished fifth.

You can't flat the tonic, then. Cause that would give you a different tonic. And you can't flat the fourth either in this system.

I don't have much use for the Lydian mode yet. I guess when I use the IV chord in the key of C I avoid writing a melody using B natural.

Vance Maverick said...

Beethoven described the third movement of op. 132 as being in the Lydian mode, but he too avoids emphasizing the feel of "tritone over the tonic". Lots of that in Bartok, though.

Vance Maverick said...

For a start on modes in Bartok, see the Sonatina.