Members Mac Attack Posted March 5, 2004 Members Posted March 5, 2004 I've been working with a bunch of semi-chromatic stuff, chalked full of secondary dominants and leading tone chords, and I was just wondering how you guys consider fully diminished 7th chords in analysis. Since every note is a minor 3rd (3 half steps) apart, the chord could theoretically have 4 names, and knowing they usually occur as vii chords only helps when working diatonically. How do you guys classify these things when you find them chromatically? I've just been going by the bass note...
Poparad Posted March 5, 2004 Posted March 5, 2004 Looking at the bass note is a good idea, usually I'll take a look at the next chord and see if it's a leading tone dim7th chord. For example, if it's an E/G/Bb/Db dim7 and the next chord is Fmaj or Fmin or some sort of F, I'll call it an Edim7. If it's a dim7 substituting for a Dom7b9, I'd either go with the 3rd of the dom7 or the b9 for naming it. For example, if the implied chord is G7b9, you might call it Bdim7 or Abdim7. In actuallity, it doesn't matter, you can call it any of the four, but that's how I've commonly seen it done in other people's music. The last common use for the chord is as an embellished dim7. For example, going from Cmaj7 to Cdim7 and back (or not back, or Cdim7 to Cmaj7, etc). Then I'd keep the root as C so it's clear how the chord is functioning.
Members Auggie Doggie Posted March 5, 2004 Members Posted March 5, 2004 Personally, I view a diminished 7th chord as a rootless 7b9 (on the Dominant, or as a secondary dominant). Why? Because I don't recognize the "vii" as a functional harmony. In C, the 'viidim7' (Bdim7) is B D F Ab, which happen to be the 3rd, 5th, b7th, and b9th of the Dominant. To my ears, the "V" (G) tonality is what I perceive...much stronger that considering the B (or the D, F, or Ab) as the root. It resolves equally well to C or Cm. Of course, as a secondary dominant, it resolves to Eb & Ebm, F# & F#m, and A & Am equally well. Because of its many possible functions, it makes for a great tool when modulating, and the symmetrical intervals mean any inversion can be used in order to maintain good voice leading. (edited for stupid mistake )
Members Fusion58 Posted March 5, 2004 Members Posted March 5, 2004 In tonal music, diminished 7th chords can function in two ways: 1) As dominant substitutions (not the same thing as a secondary dominant, BTW.) Example: VIIdim7 to IMA----Bdim7 to CMA7 2) As passing chords. Example: Dmi7 D#dim7 C/E* How do you tell the difference? If a diminshed seventh chord (regardless of its root) contains a leading tone which resolves up a half step to the root of the following chord then it is functioning as a dominant substitution. If not, then it is functioning as a passing chord. *Note that in this progression the D#dim7 chord does not contain the leading tone (B) that resolves up a half step to the root © of the following chord (C/E.)
Members edeltorus Posted March 5, 2004 Members Posted March 5, 2004 How do dim7th chords fit into this picture that follow a minor third progresison? Like the chords Adim7, Cdim7, Ebdim7 ect. Sometimes I base dreamy and mystic sounding breaks on such progressions. That's why I wonder. Nils
Members Fusion58 Posted March 5, 2004 Members Posted March 5, 2004 If you look at a diminished 7th chord you will see that it is constructed entirely of minor third intervals. Start on A, go up a minor third and you have C. Go up a minor third from C and you have Eb. Go up a minor third from Eb and you have F#. A dim7 = A, C, Eb, F# Note also that any of these four notes can be designated as the root. That is, move this chord up a minor third and you have the same four notes all over again. You can keep moving the chord up in minor thirds forever and you will still get the same four notes. Trip, huh?
Members Auggie Doggie Posted March 5, 2004 Members Posted March 5, 2004 Originally posted by edeltorus How do dim7th chords fit into this picture that follow a minor third progresison? Like the chords Adim7, Cdim7, Ebdim7 ect. Sometimes I base dreamy and mystic sounding breaks on such progressions. That's why I wonder. Nils The notes in a dim7 chord are composed of minor 3rd intervals; it's a symmetrical voicing. In other words, Adim7, Cdim7, Ebdim7, and F#dim7 all share the same notes: A, C, Eb, and F#. You could think of your progression as simply being all of the inversions of any one of those chords being played. Adim7 (root position) has A in the bass...1st inversion has C in the bass....2nd inversion has Eb in the bass...and 3rd inversion has F# in the bass. Now, if you're taking one chord shape and moving it up 3 frets at a time, then not only do you have a symmetrical chord, but you're harmonizing it with symmetrical motion; each note ascends a minor third. Because symmetrical harmony/motion gives the impression of just one voice with parallel harmony, then the bass movement will imply ROOT movement, in which case, your progression will be perceived as 4 completely different chords.
Members Mac Attack Posted March 7, 2004 Author Members Posted March 7, 2004 OH MY GOD!!! MUSICAL REVELATIONS!!!All this stuff just clicked for me- I've thought for a long time that the dim7th and dom7flat9 were almost synonomous, but i've never really put that knowledge together with tonal gravity ideas. The dom7flat9 is a combo secondary dominant/leading tone chord, because it contains both the leading tone to the tonic and the dominant 7. Thus, combining this knowledge with the ideas of secondary dominant/leading tone chords, the possibilities to use atonal chords to tonicize diatonic chords are nearly endless. FOR EXAMPLE - CHORD PROGRESSIONBm (triad)A#dim7C#dim7Em (triad) A pretty cool chromatic progression, pretty sinister too. A minor triad followed by a fully dimished 7th, followed by a fully dimished 7th a half step down, followed by another minor triad (the iv in the key of the first minor triad). At first, and to someone not in the know, (so to speak) it makes little sense other than that it goes from i to iv, except with weird stuff in the middle. However, there's really a lot more to it. In this situation, call Bm a i chord. Then the A#dim7 serves as a V7(b9), and the C#dim7 as a dominant to the Em. So the analysis would be: iV7(b9)V7(b9)/iv AKA V7(b9) of iviv Keep in mind that i've reduced the hell out of it, but this progression actually makes a lot of sense. What's so amazing is that the V7(b9) chords could be expressed musically as dim7ths moving downward chromatically.... That totally blows my mind. Thank you guys so much for all the help!
Members vote4dicktaid Posted March 7, 2004 Members Posted March 7, 2004 Originally posted by Mac Attack OH MY GOD!!! MUSICAL REVELATIONS!!! In this situation, call Bm a i chord. Then the A#dim7 serves as a V7(b9), and the C#dim7 as a dominant to the Em. Hmm... that C# dim7 cannot be a dominant substitution to Em, since it contains the note E itself (C# E G Bb). It would have to be D# dim7 (D# F# A C), or I have totally misunderstood the concept. The rest seemed right, though.
Members edeltorus Posted March 7, 2004 Members Posted March 7, 2004 Thanks for the help, folks. That's one of the better threads... (btw, I feel a bit dumb that I had the answer to my question right before my eyes.) Nils
Members Fusion58 Posted March 8, 2004 Members Posted March 8, 2004 Another use for the mi7(b5) (a.k.a. half diminished) arpeggio: To generate a minor sixth (or a melodic minor) sound over a minor chord, play the arp a minor third down from the root of the minor chord. [mi7(b5) arpeggio = 1, b3, b5, b7] Example: Play C#mi7(b5) arp over Emi. Why? Because the sixth mode of the melodic minor scale (locrian #2, a.k.a. aeolian b5) yields a mi7(5) arpeggio. Hence, C# locrian(#2) = E melodic minor.
Members Mac Attack Posted March 10, 2004 Author Members Posted March 10, 2004 "Hmm... that C# dim7 cannot be a dominant substitution to Em, since it contains the note E itself (C# E G Bb). It would have to be D# dim7 (D# F# A C), or I have totally misunderstood the concept. The rest seemed right, though. "I'm not sure how to do that thing with the quotes =(My bad though, i meant D#dim7 or B7(b9). That's some great theory though, thanks for the insight.
Recommended Posts
Archived
This topic is now archived and is closed to further replies.