interval quality question – Page 6 – Music Theory Forum

shugs wrote: ↑

Tue Nov 30, 2021 1:53 pm

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, in fact a diminished seventh chord, because it is again built over the leading tone (the seventh degree of the scale) which, in 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).