interval quality question

Chords, scales, harmony, melody, etc.
shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 5:53 am

can you all indulge me with another Music Theory 1 question.

I am looking at Major scale 7th chords...And let's take the Key of C, and the 7th scale.

so we have notes, B, D, F and A to make up the 7th chord. BDF is a diminished triad since intervals are a minor 3rd stacked on top of a minor. But when we add A on top of F, we are adding a Major third.

My book says the quality of the 7th is a minor and that this chord is called a diminished minor 7th, or a half-diminished 7th...I don't care what the chord is called, but I don't understand why they are saying the quality of the 7th is a 'minor;

can anyone help ?

User avatar
fmr
KVRAF
10703 posts since 16 Mar, 2003 from Porto - Portugal

Post Tue Nov 30, 2021 6:06 am

shugs wrote:
Tue Nov 30, 2021 5:53 am
can you all indulge me with another Music Theory 1 question.

I am looking at Major scale 7th chords...And let's take the Key of C, and the 7th scale.

so we have notes, B, D, F and A to make up the 7th chord. BDF is a diminished triad since intervals are a minor 3rd stacked on top of a minor. But when we add A on top of F, we are adding a Major third.

My book says the quality of the 7th is a minor and that this chord is called a diminished minor 7th, or a half-diminished 7th...I don't care what the chord is called, but I don't understand why they are saying the quality of the 7th is a 'minor;

can anyone help ?
That chord is the leading tone seventh chord, because it is built over the leading tone (the seventh degree of the scale). It only exists in Major mode (major scales). Although it has a diminished fifth, the seventh is, in fact, a minor seventh.

In minor mode scales that chord is a diminished seventh chord, and it is also built over the leading tone (the raised seventh degree of the scale). The leading tone in a minor mode is a raised tone. That raised tone will form a diminished seventh with the sixth degree, which is the seventh of the chord.

To sum it up the leading tone seventh chord belongs to Major. The diminished seventh chord belongs to minor. Both are built over the leading tone (seventh degree) which, in minor, is raised (otherwise it would not be a leading tone).
Last edited by fmr on Tue Nov 30, 2021 9:53 am, edited 2 times in total.
Fernando (FMR)

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:10 am

I dont understand why the quality of the 7th, is called 'minor' in a Major scale. The 4th note we are adding is a Major triad over the 5th.

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:14 am

(when we add the 7th to scale degrees I and IV, we call the quality of the 7th a Major which makes intuitive sense to me)

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:15 am

and when we add the 7th to scale degrees 2,3,5,and 6 we call the quality of the 7th a Minor, which also makes sense to me

shawshawraw
KVRist
336 posts since 4 Aug, 2020 from Montreal, Canada

Post Tue Nov 30, 2021 6:24 am

shugs wrote:
Tue Nov 30, 2021 6:15 am
and when we add the 7th to scale degrees 2,3,5,and 6 we call the quality of the 7th a Minor, which also makes sense to me
Are you sure about the 5th degree V?

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:30 am

yes...In the key of C the 7th is GBDF...DF is a minor3rd being added on top of a Major triad. The quality of the 7th is called a minor

shawshawraw
KVRist
336 posts since 4 Aug, 2020 from Montreal, Canada

Post Tue Nov 30, 2021 6:45 am

shugs wrote:
Tue Nov 30, 2021 6:30 am
yes...In the key of C the 7th is GBDF...DF is a minor3rd being added on top of a Major triad. The quality of the 7th is called a minor
...

Anyways, the names of chords are something you have to know because they reflect their distinctive sonic signatures. Calling a 7th chord "major" or "minor" quality is way too vague (if not bullshit).

In the key of C, we have CMaj7 Dm7 Em7 FMaj7 G7 Am7 Bm7b5.

The G7 and Bm7b5 are just unique ones, as their names suggest.

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:49 am

I understand memorization, And I am not talking about the naming of the chord.

I am trying to get at the 'why' they are saying the QUALITY of the 7th is a minor....Usually naming something has some logic behind it and I cannot fathom this one

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:52 am

The quality of the 7th is minor when we had a minor third and the quality of the 7th is major, when we add a major third EXCEPT when we add a major third to the diminished 7th triad in a Major scale. There is a reason ( I assume)

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 6:55 am

Actually, I think I just figured it out.....They are looking at the quality of the interval from the root to the 7th and saying that is the quality.....Now it makes sense

User avatar
fmr
KVRAF
10703 posts since 16 Mar, 2003 from Porto - Portugal

Post Tue Nov 30, 2021 6:55 am

shugs wrote:
Tue Nov 30, 2021 6:49 am
I understand memorization, And I am not talking about the naming of the chord.

I am trying to get at the 'why' they are saying the QUALITY of the 7th is a minor....Usually naming something has some logic behind it and I cannot fathom this one
They say the 7th is minor BECAUSE THE 7th "IS MINOR". What's so difficult in there? For the chord to be called a diminished 7h, it must have a diminished 7th.
Last edited by fmr on Tue Nov 30, 2021 9:52 am, edited 1 time in total.
Fernando (FMR)

User avatar
fmr
KVRAF
10703 posts since 16 Mar, 2003 from Porto - Portugal

Post Tue Nov 30, 2021 6:56 am

shugs wrote:
Tue Nov 30, 2021 6:55 am
Actually, I think I just figured it out.....They are looking at the quality of the interval from the root to the 7th and saying that is the quality.....Now it makes sense
Exactly
Fernando (FMR)

shugs
KVRist

Topic Starter

70 posts since 24 May, 2021

Post Tue Nov 30, 2021 7:01 am

yeah, I was looking at the third that was being added , and not the distance between the root and the 7th

jancivil
KVRAF
23641 posts since 20 Oct, 2007 from gonesville

Post Tue Nov 30, 2021 8:01 am

back to where you didn't care about 'diminished/minor 7th' (note the slash): the first bit there is the quality of the triad, then the quality of the seventh. This is the common practice nomenclature.

in major: I7 is major/major; ii7 is minor/minor; iii, 7 minor/minor; IV, major/major; V, major/minor, vi, minor/minor; vii diminished/minor.
In minor with an harmonic focus, ie., a raised 7/leading tone, vii is diminished/diminished, a diminished seventh chord (as opposed to half-diminished 7th on vii in major; & the ii in minor is a dim/minor, eg., Dø7 in C minor.

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