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Diminished vs. m7b5

Posted: Wed Dec 10, 2008 1:16 pm
by strachs
I find it weird that in the Concept, the Diminished chord color is thought to belong to MG I and make it's first appearance in the 9-tone order with the Lydian Diminished scale. My intuitive relationship with the diminished chord places it on MG +IV, since even in the 7-tone order a diminished triad exists there.

I understand that the symmetrical four-note chord usually referred to as "diminished seventh" is, after all, symmetrical, and can therefore any of it's tones can be considered it's tonic. But isn't a chord's modal genre supposed to be determined by it's most native, most ingoing tonal environment? Does "diminished seventh" really have more in common with Major than m7b5? In other words, is MG I really it's natural home, or should the three- note version (dim triad) determine the MG and place it on +IV instead?

At the very least.... is there some justification in jazz or other music tradition for thinking of the diminished chord color as MG I?

Posted: Wed Dec 10, 2008 1:24 pm
by strachs
By "intuitive relationship" with the chord, of course, comes from the usage of the diminished triad as well as the m7b5 (or half-diminished) chord in classical music.

In a minor key, the fundamental cadence form is ii-V-i, with ii being a diminished triad (or if a four-note chord is used, the "half-diminished" chord, referred to in Concept as m7b5), or MG +IV of the Lydian #2 scale (otherwise known as Harmonic Minor).

I'm not familiar enough with jazz to know the primary usage for diminished chords, so I don't know what underlying thinking may have been behind Russell's placement of these chords on MG I.

Posted: Wed Dec 10, 2008 5:07 pm
by sandywilliams
I hear a Bbdim/maj7 or A/Bb as having a pretty MG sound that doesn't have a relation to a m7b5 genre ('cept G m7b5, or Emi7b5).

Posted: Thu Dec 11, 2008 9:50 am
by strachs
That's interesting. I'm not familiar with that chord color (dim/maj7), but you're right is a pretty one. And it's most ingoing placement is on MG I.

I was thinking more of the diminished TRIAD, which occurs in the 7-tone order on MG +VI. It seems consistent to place the "fully diminished tetrachord" here, too. But as you mentioned, then it doesn't accommodate the dim chord with a major seventh.

Placing it on MG I would allow for the old 'Cdim - Cmaj' chord progression that sounds so swingy, without considering it as two completely different tonal areas. Simply a higher tonal order resolving to a lower one.

To my ears, a Bb dim/maj7 chord turning into a Bb dim7th, and Bb m7b5 turning into a Bb dim7th both sound equally related to the dim7th chord.

Maybe the structure of the fully diminished tetrachord possesses a duality, similar to that of the Major scale. Still many mysteries in the realm of harmonic language..........

Posted: Thu Dec 11, 2008 10:22 am
by strachs
To my ears, a Bb dim/maj7 chord turning into a Bb dim7th, and Bb m7b5 turning into a Bb dim7th both sound equally related to the dim7th chord.
:oops: You know, listening a little closer: the dim/maj7 and dim7 actually sound EQUAL in dissonance. Whereas m7b5 has a slightly increased level of dissonance.

Sandy, my dear, you're right on the money. (Or should I say Russell was). As counter-intuitive as it may be for me, MG I seems to be the most natural home for dim7th. As much as I hate to be wrong, it's great to be forced to look (or in this case listen) more closely to the seemingly familiar. I now have a more accurate perception of my old pal the dim7 chord. Thanks a million.