I'm trying to figure out the diatonic triads of a scale (such as I-ii-iii-IV-V-vi-vii*), but for 7th chords. I've been using intervals to decipher them, for example if I'm doing this in the key of C, and trying to find the diatonic triad of D, I know that the 3rd, 5th, and 7th interval of D is F, A, and C. I also know that the D major scale has F and C sharpened, therefore comparing that I can build a formula- 1-b3-5-b7, yus?

If I'm doing this in the key of B, and trying to find the diatonic triad of G, it would be the same process as above, but you'll have to worry about the sharps in the key (B), yea yea? The 3rd, 5th, and 7th of G is B, D, and F. The major scale of G has a sharpened F. The major scale of B has sharpened F, C, G, D, and A. Then you compare 'em like so.

G# B D# F#
G B D F#

'ight so this got my confuzzled for a bit because the outcome should be 1-b3-5-b7, yea yea. But then you compare it down add as it is and you get.

#1-3-#5-7

Flatten everything to make the 1 not sharp and you get 1-b3-5-b7 as intended.

'ight I've been explaing this thought process as it seems the best way/easiest to figure out these things. Once you have the major scale memorized and intervals everything does seem pretty simple. Is the right way I should go about deciphering chords and similar?

Anyways, back onto the main question trying to find the diatonic triads of a key in 7th chords, I've came up with:

CMaj7
Dm7
Em7
FMaj7
G7
Am7
Dim7?

The dimished 7th is the one that's confusing me (is it a dim7?). Again, trying to figure out this in terms of intervals, you have the basic diminished chord.

The 7th of B is A#. In the key of C it's A. So.. I'm gettin' (1-b3-b5-b7).

Alright so.. I posted this a while back and a diminished 7th chord is (1-b3-b5-bb7). From what I've heard, diminished chords are stacked with minor 3rds on top of each other.. and a dominant 7th (1-3-5-b7) already has a flattened 7th in it's formula thus making it double flat? I'm not sure.. that's what's confusing me.

(1-b3-b5-b7) would be a half diminished chord, then. But then again.. thinking back to deciphering chords using intervals..- you have B diminished chord, then you add the 7th (b7). So.. wouldn't you call that a diminished 7th.. Like for example if the 7th was not flattened making it (1-b3-b5-7).. wouldn't you call it a diminished major 7th?

Is (Bdim)7 the same thing as (B)dim7? If not things would make sense.

I'm not sure exactly my question is but it seems to be clashing with my thought process with intervals. Think it may have something to do with these diminished and agumented chords and how exactly they're constructed.
Last edited by Zvahl at Jul 13, 2009,
Your example of a 1-b3-b5-7 would probably be written as an XmM7b5 or something like that. But in your example, it is a half diminished chord. The definition of a half diminished chord is a diminished chord with a minor 7th.
Quote by Anteaterking
Your example of a 1-b3-b5-7 would probably be written as an XmM7b5 or something like that. But in your example, it is a half diminished chord. The definition of a half diminished chord is a diminished chord with a minor 7th.

Right. Adding onto that, a fully diminished chord is 1-b3-b5-bb7.
'ight so I figured out how those diminished chords work. 4ths and 5ths get diminished by half step while major intervals get diminished by 2 half steps, down from a minor interval. So 1-b3-b5-bb7 makes sense for diminished.

Is (Bdim)7 the same thing as (B)dim7? If not things would make sense.
I think a diminished chord is stacked minor 3rds...and your vii 7th chord is Bm7b5, otherwise known as half-diminished
Quote by zhilla
I think a diminished chord is stacked minor 3rds...and your vii 7th chord is Bm7b5, otherwise known as half-diminished

Yep this is true
shred is gaudy music
Quote by zhilla
I think a diminished chord is stacked minor 3rds...and your vii 7th chord is Bm7b5, otherwise known as half-diminished

Yes various chords can have different names mostly on how they're viewed. What I'm asking is, is a (BDim)7 different than (B)Dim7? They're read the same but the way I see it for the first one is- you have a B diminished chord (1-b3-b5) you then you add a 7th on it, hence (Bdim)7. For the second one you have a B chord, then a Diminished 7th, as a whole (1-b3-b5-bb7). Normally you don't see the parenthesis which lead me to believe they're the same thing, but I dunno.

You could also see it as an added chord- Bdim(add7).. which while writing this realized that's what I'm doing, but I don't know if I can do the same thing with extended chords like 11ths and 13ths..

Hmm, guess I'll have to look more into added chords. .

Edit: But still, if you apply the same reasoning with a minor chord instead of diminished..

For example you have a B minor, then a 7th. That could be Bmin(add7)

But also Bmin7.

Then you have a B diminished, then a 7th. That could be Bdim(add7)

But why not Bdim7? Would make sense, doesn't it? Instead it's half diminished, which I can understand (stacking minor 3rds on top of each other or a 7th interval needs 1 whole step to become diminished), but why doesn't this apply to major/minor stuff?
Last edited by Zvahl at Jul 16, 2009,
Quote by Zvahl
I'm trying to figure out the diatonic triads of a scale (such as I-ii-iii-IV-V-vi-vii*), but for 7th chords. I've been using intervals to decipher them, for example if I'm doing this in the key of C, and trying to find the diatonic triad of D, I know that the 3rd, 5th, and 7th interval of D is F, A, and C. I also know that the D major scale has F and C sharpened, therefore comparing that I can build a formula- 1-b3-5-b7, yus?

If I'm doing this in the key of B, and trying to find the diatonic triad of G, it would be the same process as above, but you'll have to worry about the sharps in the key (B), yea yea? The 3rd, 5th, and 7th of G is B, D, and F. The major scale of G has a sharpened F. The major scale of B has sharpened F, C, G, D, and A. Then you compare 'em like so.

G# B D# F#
G B D F#

'ight so this got my confuzzled for a bit because the outcome should be 1-b3-5-b7, yea yea. But then you compare it down add as it is and you get.

#1-3-#5-7

Flatten everything to make the 1 not sharp and you get 1-b3-5-b7 as intended.

'ight I've been explaing this thought process as it seems the best way/easiest to figure out these things. Once you have the major scale memorized and intervals everything does seem pretty simple. Is the right way I should go about deciphering chords and similar?
Dude you got there but you went the looong way around.

The problem you had I think is that you were trying to find the chord with the root G that is diatonic to B major. As you pointed out the G♯ is diatonic to B major, but the G is not. Trying to find the chord with root G that is diatonic to B major is flawed because G itself is not diatonic to B major. Hence problems.

Instead what you're should have been looking for is a chord with the root G♯ that is diatonic to B major.

So if you consider the notes that get stacked to find the diatonic G♯ seventh chord from the key of B Major you get
B major = B C♯ D♯ E F♯ G♯ A♯
So stacking notes from G♯ you get G♯ B D♯ F♯

Now though it is not really used the G♯ major key looks like this
G♯ A♯ B♯ C♯ D♯ E♯ F♯♯

So comparing we see that G♯=1; B=♭3; D♯=5; F♯=♭7 so our chord is spelled 1 ♭3 5 ♭7 = a minor seventh chord.

It's easier still if you just learn to recognize intervals on the spot. A major third above F♭ is ...? A major third above C is ...? A diminished fifth above A is ...? and that kind of thing. Then you don't need to compare them back to the key of the root to get the intervals you just know them.

Quote by Zvahl
Anyways, back onto the main question trying to find the diatonic triads of a key in 7th chords, I've came up with:

CMaj7
Dm7
Em7
FMaj7
G7
Am7
Dim7?

The dimished 7th is the one that's confusing me (is it a dim7?). Again, trying to figure out this in terms of intervals, you have the basic diminished chord.

The 7th of B is A#. In the key of C it's A. So.. I'm gettin' (1-b3-b5-b7).

Alright so.. I posted this a while back and a diminished 7th chord is (1-b3-b5-bb7). From what I've heard, diminished chords are stacked with minor 3rds on top of each other.. and a dominant 7th (1-3-5-b7) already has a flattened 7th in it's formula thus making it double flat? I'm not sure.. that's what's confusing me.

(1-b3-b5-b7) would be a half diminished chord, then. But then again.. thinking back to deciphering chords using intervals..- you have B diminished chord, then you add the 7th (b7). So.. wouldn't you call that a diminished 7th.. Like for example if the 7th was not flattened making it (1-b3-b5-7).. wouldn't you call it a diminished major 7th?

Is (Bdim)7 the same thing as (B)dim7? If not things would make sense.

I'm not sure exactly my question is but it seems to be clashing with my thought process with intervals. Think it may have something to do with these diminished and agumented chords and how exactly they're constructed.

As other people have said it helps if you know the various kinds of chords.

The chord you are talking of a half diminished seventh or a minor7♭5 chord is one of the chords we get from a diminished triad base.

The diminished triad is 1 ♭3 ♭5. Now if we add a major third on top of this base triad we get 1 ♭3 ♭5 ♭7 since the distance from a ♭5 to a ♭7 is a distance of a major third.

The resulting seventh (the ♭7) is a minor seventh. Hence we call it a Half diminished seventh chord because the fifth is diminished in the diminished triad but the seventh is NOT diminished it is minor in quality.

If we took our diminished triad base and added a minor third on top we get the following
1 ♭3 ♭5 ♭♭7. The distance from the ♭5 to the ♭♭7 is an interval of a minor third. The result this time is a seventh that is not major, not minor, but diminished in quality. Hence both parts of the chord are diminished the base triad and the seventh. We call this a diminished seventh or fully diminished seventh chord.

The way we write each chord is as follows:
1 ♭3 ♭5 ♭7 = half diminished = Cø7 or Cm7♭5.

The second way is the one I've seen most often. We can understand this name by viewing the chord as a Cm7 (1 ♭3 5 ♭7) with a flat fifth resulting in our half diminished 1 ♭3 ♭5 ♭7 chord and our name Cm7 with a ♭5 = Cm7♭5.

1 ♭3 ♭5 ♭♭7 = diminished seventh = Cº7 or Cdim7

The Cdim7 is not a diatonic chord. It will always have at least one note that is out of key. It sounds like a hell of an ugly chord but it does however have it's uses.

The chord you're looking for as mentioned already is the half diminished 1 ♭3 ♭5 ♭7 = Cø7 or Cm7♭5.
Si
Last edited by 20Tigers at Jul 16, 2009,