I had the opportunity to come across a E#dim (like Fdim) a few nights ago and it got me to thinkin' about those nasty chords again. My memory tells me a dim7 chords has the root and the other 3 notes ascending by a minor third interval. But something seemed wrong. Let's take the easy key of C:
C = C E G
Dm = D F A
Em = E G A
F = F A C
G = G B D
Am = A C E
Bdim = B D F G#
The individual notes of every chord were made up from the C major scale (C, D, E, F, G, A, B) except the evil dimished chord. What's the deal with the G#? The key of C has no sharps or flats. There's a G and an A in the key but not G#. Can someone help me with the thory on this?
I'm going to try this agin in the key of A to see if I've lost it.
A = A C# E
Bm = B D F#
C#m = C D# G#
D = D F# A
E = E G# B
F#m = F# A C#
G#dim = G# B D F
I see E and F# in the scale but no F. Still not getting it.
:oops:
"Nothing...can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts."
Ok, here's the deal:
The diminished triad (not the diminished seventh) is native to the key. So in the key of C, you've got Bº (B-D-F) and in the key of A you've got G#º (G#-B-D).
But the diminished seventh is often substituted for the diminished triad. Like many other chord substitutions, it's an extension - the intended triad is present in the diminished seventh - so the core sound is there.
The real reason diminished sevenths are used more often than diminished triads is that there's only three of them. That makes them very easy to remember. You've got:
C-Eb-Gb-Bbb
C#-E-G-Bb
D-F-Ab-Cb
The next half step up is D#/Eb... which is Eb-Gb-Bbb-Dbb. That's the same notes as the Cº7!
Guitar teacher offering lessons in Plainfield IL
Also the VII diminished seventh adds another tritone to the mix. Your scale degrees are 7, 2, 4, b6. In the key of C, B-D-F-Ab. You have the B-F tritone (diminished fifth) and now also the D-Ab tritone (your second diminished fifth) and lastly, the second interval between Ab and B (or seventh). This makes for a lot of dissonance.
When you resolve this chord properly back to the tonic (or heck, probably improperly since it's a guitar) you really confirm the key. It goes from a lot of dissonance to total clarity, "Ah. Now that's the tonic chord I'm hearing now."
At least I think that's how it works. I'm still learning myself!
Cool, I thought I lost my mind. I was a bit angry at "theory" when I thought about it. Now I'm calm and happy. :-) I love those who can answer questions. Give me a smile.
:D
Good or bad, I most often take that dim, flatten it and make it a major or play a dom7th as a substitute. I know, cheating. I'll get to playing the real deal later on. But if I'm with a group of people, I'll generally hit only 3 of the 4 notes to make it easier knowing they are providing the 4 note.
"Nothing...can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts."
I just thought of another reason why diminished chords go out of key. You mention G# in the key of C. Well, the relative minor of C is A. In classical theory, the raised 7th scale degree (G#) is needed to create the "leading tone" to get back to the tonic in a minor key. #7 pulls much more strongly to 8 than regular 7.
So the VII dim 7 in Am is going to go out of key, too. Its notes will be G# B D F (in this case #7, 2, 4, 6. We don't flatten the 6 of the VII dim 7 chord in a minor key because the sharpened 7 takes care of it all.) G# to D is your diminished fifth, and B to F is your diminished fifth (or augmented fourths depending on what inversions you are using) and F to G# is your major second now.
Try playing a few chord changes in Am, then when you decide to finish, play E major (which has the leading tone, G#) before you go back to A minor. Hear how it makes you expect to hear the A minor chord? That's what you want. You can also test it with some simple A minor melody and end your phrase with G# A. Also, if you are ending your minor-key phrase in the 6-7-8 fashion, western theory tells us to instead use #6 #7 8. You will find that this pulls much stronger to the tonic than regular 6 7 8 as well.
"#6 #7 8. You will find that this pulls much stronger to the tonic than
regular 6 7 8 as well."
Okay, in C the #6 would be A#, #7 would be the octave or C and the 8 would be octave C. Are you sharpening a dom7 or a MAJ7?
"Nothing...can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts."
Okay, in C the #6 would be A#, #7 would be the octave or C and the 8 would be octave C. Are you sharpening a dom7 or a MAJ7?
It's minor, in A the #6 and #7 would be F# and G#, in C minor, it would be A natural and B natural. Another way to think of the melodic minor is as a major scale with a b3.
Steve-0
