Re: [Harp-L] Chords and Modal Scales - Interrelationship(?)



robert cole asked about chords and modal scales...

Hi Bob,


I'm not sure if I have the answer you're looking for here, but I'll try...

mode), I was struck by something odd(?) regarding the thirds and >> fifths
of> the chords that I have not seen discussed in music >>theory books.
(1) The notes used for the thirds of the chords form a Phrygian >>scale.

3rds from each chord as in I, ii, iii etc? So that would be E, F, G etc. in C? That's because each major scale is cyclical, as in, once you get back to the root an octave higher, you're dealing with the same notes. I'm not sure if that's what you're looking for - you know all that already. The third mode of a major scale is the phrygian mode, which as Vern says, has the relationship HWWWHWW between each interval - as Vern points out, the position of each of the two semitone (H) intervals change.

Do you mean that if you add thirds all the way up to a two octave interval,
that you get the modal scale on which you were originally basing the scale?

As in C E G B D F A?  If that's the case, then the answer is in the
question, that the chord comes from the scale.  That's not useless
information by the way, and it shows the way a lot of jazz people think,
that chords are interchangable with scales.  The call this the "chord/scale
approach".

You mention the mixolydian mode - building a chord from that leaves you
with:
G B D F A C E (G13sus)

So if you saw this symbol G13sus or even G13 or G9 or G7, it would be an
indication to use the mixolydian mode when improvising.

To answer your specific questions:

(1) Does this information provide an interesting way to "cook up" >some
harmony during solos,

Not really, to the best of my knowledge.  Once you know the modal scales and
their characteristics, knowing that it's the same scale as based off the
13th doesn't give you anything.

or is this unusable (useless) knowledge and merely an > oddity?

Well, it's another way of looking at the same information. The more ways you reinforce the relationships between scale tones and chords, the better.

To me there are two things to be gotten out of this:
a. 9 = 2, 11 = 4, 13 = 6 - as in the 9th is just the 2nd scale tone up an
octave.
b. if you stack thirds above a particular chord, you get another one, and
you know that they are someway related and may be *substituted*.  For
example, Am7 = A C E G, if you leave of the A, then you have the triad of C
major.  So you would think that Am and Cmaj substitute for each other a lot,
and you'd be right.

(2) Does anyone have suggestions for taking advantage (if possible) of
this
interrelationship between diatonic chords and modal scales for practical
(NOT theoretical) purposes on harmonicas?

The chord and the context (key of the song etc) will give you an option for a scale to use when improvising or composing.


(3) Is this one of the (possibly many) reasons that harmonica >experts recommend learning ALL of the modal scales, as well as a host of >other scales (major and minor pentatonic, blues, whole-tone, harmonic >minor, melodic minor, jazz minor, etc.)?


I wouldn't really say so. Each mode has a particular "colour" and certain characteristics, for example dorian has a natural 2nd and natural 6th, whereas in phrygian, both the 2nd and 6th are minor. So any melody using the dorian mode may exhibit those characteristics (they will if you play the 2nd and 6th!). All the other scales you mention, such as the whole tone, blues scale, melodic minor and modes of that, will give certain colours that are useful to you. They are part of a musician's toolkit. The recommendation may come from the fact that if you don't hear the differences and characteristics of each mode when improvising, and you think, "oh well, D dorian is the same as Cmaj, I'll just noodle around C maj", then you will sound like you're noodling around C major!

I hope that helps, and again, doesn't confuse.

Buy my book :-)

Eugene




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