Diminished vs half diminished question

Discussion in 'Music Theory [DB]' started by ryco, Oct 10, 2005.

  1. ryco


    Apr 24, 2005
    I had originally posted this question over in the Bass Guitar section but didn't feel I received an adequate answer. Looking over here in Double Bass I notice you have a section devoted to theory questions so I will try over here. Forgive my bad if I have messed up the proper etiquette for double posting (I am really a bass guitar guy!).

    Can someone explain the function of a fully diminished chord/scale. And where does a full diminished chord occur naturally? It's got that funky old-timey sound to it but I hardly ever hear it used anymore. How does it resolve?

    Full dim: R, M2, m3, P4, d5, bb7, (M7)

    Half diminished occurs all over the place (vii in Ionian) and functions as a substitute for V (V9 without the root) a lot. Used as a substitute for minor chords sometimes; ex m9b5

    Half dim: R, m2, m3, P4, d5. m6, m7
    I did receive an answer about an 8 tone scale called a half whole dim:

    R, m2, m3, d4, d5, m6, M6, m7 -- and I know the converse

    R, M2, m3, P4, d5, m6, M6, M7 but I look at these scales as merely interesting anomalies to goof around with.

    Mostly I wanted info on the full diminished scale; what is its function and how does it resolve -- what can I do with this chord?
  2. westland


    Oct 8, 2004
    Hong Kong
    My jazz teacher contended that diminished chords were almost always substitutions. The blues players would use them because you essentially get 4 chords in one (the dim chord is symmetrical around each of its notes) ... the sub is often for the half dim -- Rmb5b7. In fact in fake books, you often see the dim chords written with the wrong root.

    I'd posted on dim chords in another thread. The diminished started being used back at the end of the Baroque period (CPE Bach writes about it ... but only the tritone, no bb7) as instruments became louder with more complex harmonics, and as music began to use more colorful harmony, and needed more dark, dissonant chords in their arsenal.

    My explanation may make more sense for piano perhaps than for bass. See what other responses you get here ... I think opinions vary widely on the diminished chords.
  3. Brent Nussey

    Brent Nussey

    Jun 27, 2001
    Tokyo, Japan
    Ok. First, the diminished scale *is* a symmetric scale.

    Cdim Chord:
    C Eb Gb A

    Cdim scale:
    C,D,Eb,F,Gb,Ab,A,B (no bbs or ##s for clarity)

    In your scale you've left out one of the notes, and it's a chord tone. Just because in triadic (three-note) harmony you don't play the (double flat) seventh, doesn't mean you leave it out of the scale. What scale would you play over a D- chord in the key of C? D,E,F,G,A,B,D? No, you'd include the C, even though the chord isn't written as D-7. The same applies here.

    I disagree with the idea that diminished chords are almost always substitutions, if you look at old American sheet music, you'll see the chords all over the place, usually for tension/resolution purposes. I'll have to leave the why's to someone else for that. These days you often hear those chords replaced by a II-V, or a related dominant sound. But I understand why Westland's teacher might make such a comment. It's common in some circles to see a progression like this:

    |Eb |G-7 C7 |F-7 |A-7 D7 |etc

    replaced by this:

    |Eb |Eo |F-7 |F#o |

    "half-diminished" or -7b5, is not a substitution for -7 per se, it's a part of minor harmony. You'll usually see it in a "minor II-V," going to V7b9 (not "V9") and on to I- in the key of the moment.

    | A-7b5 |D7b9 |G-7 | etc

    It's just a different thing altogether. You should learn a little about harmony, and minor harmony in particular, to put this all together.

    About half-whole diminished, here's the thing. It's very common for players to play diminished scale-based ideas on dom7th chords. For example, on C7: Eo or Go or Bbo or Dbo. Playing these at the piano will show you that they are all the *same* scale, just starting on a different note. So if you want to know what C scale to play for a diminished sound on C7, let's write the E/G/Bb dim scale starting on C:


    There you have it, the half-whole dim scale. Whole-half and half-whole are the same scale, just using a different note as your reference, or "starting" point.

    So these *are* the diminished scales, not interesting anomalies. About your last question, I'm not sure, are you asking how you can use this sound in composition, or improvisation (how does it resolve? etc). In any case, I really think you should get a proper harmony book and learn about these things in some sort of organized context. I've heard the Jazz Theory Book is a good one...

  4. Bobby King

    Bobby King Supporting Member

    May 3, 2005
    Nashville, TN
    The naturally occuring triad of the 7th degree of a major scale is diminished. It can be thought of as an incomplete dominant 7th chord because if you played the 5th of the major scale under it, you'd have a V7 chord. Likewise if you added the naturally occuring 7th to that triad (the 6th degree of the major scale) you'd have a "half-diminished seventh" chord which can also be thought of as an incomplete dominant 9th -- add the 5th again under it and you get a V9.
    Before the time of Bach (and in much of his music as well) , it was more common to hear these incomplete dominants than the full V7's we're so used to. Bach really began to establish the Dominant-Tonic progression that is the cornerstone of our harmony.

    When you use a common diminished chord like #Idim or #5dim, they are usually substituting for secondary dominants (VI7 and III7 respectively). So if you went from I to #I to ii minor, the #I dim would substitute for a VI7 chord (the V of ii).

    A half-diminished 7th chord naturally occurs as the ii chord in a minor key. As someone has already mentioned, it is often the ii chord in a minor key II -V -I. This will have a much different function than the vii7 in major.

    People that only think about chords and harmony from a pop or jazz perspective should try and learn a little more basic theory and history. Before there were "chords" per se, there was the simple counterpoint of two voices, and then choral music using three voices or more. Each of these voices was singing or playing a melodic line of it's own and chords were the result of the interaction. We tend to think of chords as "blocks" under a melody, but this was not always the case.
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  5. jazzbassnerd


    Aug 26, 2002
    The fully diminished chords occurs on the seventh degree of a harmonic minor scale.


    C Harmonic Minor

    C D Eb F G Ab B C

    B dim 7

    B D F Ab

    This is where this chord occurs "naturally." The naturally occurring V (five) chord in natural minor would be minor (G D Bb) which would not function well to return to i (one). Thus, we get a raised 7th scale degree (harmonic minor). If you extend the V chord to the 9th (as someone said above) you would get G B D F Ab (this is where we get the a dominant flat 9 chord in a minor two five progression).

    The way the resolution works out depends on how you are using it. I mainly think of it either functioning as a V chord or as a passing chord. Hope this helped someone.

    (I hope its all right too)
  6. westland


    Oct 8, 2004
    Hong Kong
    These are all great observations, and I'm learning something from you guys. In truth, I'm not sure that I truly believed that diminished chords are always subs, but guess I hadn't really thought enough about what other functions they would serve. These are insightful posts ... thanks. :D
  7. Bobby King

    Bobby King Supporting Member

    May 3, 2005
    Nashville, TN
    Exactly. In harmonic minor, the vii7 chord once again can be thought of as an "incomplete dominant 9th", in this case it's a "V7b9" -- the b9 is the naturally occuring 9th in minor.

    This is where traditional and jazz/pop theory diverge. In jazz terminology, you can take a root and build any type of chord on top. A "1" chord can be a 7th, major 7th.. a "2" can be major, b5, etc. In traditional harmony, chords are built using a succession of thirds derived from a scale. So if you're in a major key, the I is major, if it has a 7th, it is a major 7th. The ii will always be minor or minor seventh. The V is the only place you get a dominant seventh chord. The seventh degree is where diminished enters the picture.

    Many of the so-called "jazz chords" have their origins in traditional contexts. For instance, what is often called a "6th" chord, 1-3-6 is nothing more than an inverted minor triad.

    I have found that there's very little in jazz, harmonically speaking, that wasn't already fully explored by the early 20th century (and earlier). Listen to the music of Brahms, Chopin, Tchaikovsky, Debussy or Ravel and you'll hear just about any "jazz chord" you can imagine.

    Of course in many other important ways jazz differs from classical music -- for instance it's emphasis on rhythm and improvisation.
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  8. nypiano


    Feb 10, 2003
    R, M2, m3, P4, d5, m6, M6, M7 but I look at these scales as merely interesting anomalies to goof around with.

    Mostly I wanted info on the full diminished scale; what is its function and how does it resolve -- what can I do with this chord?

    It's hard to figure this out--as far as I know the 1/2 W diminished and a full diminished are the same thing. Assuming there is no distinction being drawn on this (?)

    When you talk about what can I do with this chord or what can I do with this scale reflects what kind of approach you're taking. If you are taking a more "harmonic function" based approach then you might want to think of the diminished chord you're on as more harmonic minor based or temporary harmonic minor based. The 1/2 W can sound a little forced or chromatic in those cases. For example a Jobim tune. You can make it work but that "goofing around anomaly" aspect really is that chromatic, major/minor, symmetrical aspect of the 1/2 W dim scale. It makes you want to detail that chord as almost an end unto itself-a florid colorization of a sound if you will. For example when I'm dealing with a more bebop oriented line and I run into C-7 C#o D-7, the 1/2 W dim's D# creates a "what is that?" tension that makes me want to avoid the issue altogether. I could opt for 7th mode of D harmonic minor. Or simply hop over and play C# E A G. It's really a question of intent and what are the most important tones you are going to.

    In terms of diminished chords and what they are functionally. In standard tunes and early swing tunes from let's say the 20s and 30s I think we got a little diminished happy. So for example tunes were written with diminished chords in all manner of sequence. It sounds a little dated now.

    That aside, the most basic boil down is that a diminished chord can only do 3 things in terms of the root motion: go up, go down or stay there and most if not all can be boiled down to the following:

    1. A dominant sub with the 3rd in the bass. Root motion 1/2 step up

    C C#o (Subs for A7b9) D- (Dont Get around much..).

    2. As a half step above passing chord alternative. root motion 1/2 step down. Most frequently if not always on these steps: bIIIo to II.

    G Bbo A-7 (Embraceable you)

    3. As a diminished I suspension
    Ebo Ebmaj (Star Eyes)

    In reality all 3 sounds are very related. For example #1 and #3 as equivalents:

    F#o G-7 or Ebo Ebmaj is nearly the same thing. Just different root motion.
  9. Howard K

    Howard K

    Feb 14, 2002
    man, that post above is great. all these posts are great. really intersting stuff.

    I clearly cant add anything to the above post, it captures everything i knew and all the places I've come accross dim chords, and loads more!

  10. nypiano


    Feb 10, 2003
    Actually I might have overreached on the diminished half step down example as "always" on bIII(ie G Bb A-). It's definitely very often anyway. Make note of it in as many tunes you can anyway.

    It seems to me I've seen this kind of thing too: F#-7b5/ Fmaj (Fo)/ E- (although again F- is more common than Fo) This a variation on the "roots in" equivalent of D7 /D-7 G7b9)/Cmaj. In any case it's an example that does/could work where the diminished goes down half step as a dominant sub. Or maybe this too A- Abo C/G
  11. Howard K

    Howard K

    Feb 14, 2002
    My originals band (not jazz by any stretch of the imagination) have a progression that uses Maj triad to dim triad built on the same root.. the specific changes are, in 12/8, one chord per dotted crochet..

    G / Gdim / D / Ddim

    So the root stays same and the notes making up the triad descend a semitone. I'd never seen this before our band leader used it, but since then I've seen in a number of times.. of course I cant even vaguely remember where!

    I've seen dim7th chords used as "connecting" chords before too, in at least one tune... so, as per your example, you get
    CMaj7 / C#dim / D-7

    And the obvious one being a sub for the IV or V chord, raising the root on a dominant 7th chord

    There seem to be diminsihed 'shapes' all over the shop in loads of tunes, in anything with lots of extenstions they seem to just come out of the woodwork :eek:
  12. nypiano


    Feb 10, 2003
    Well as a composer you have the right to do whatever you like obviously including far out progressions. Often with things outside of jazz, especially rock you get progressions that fit the composer's intentions but don't follow the "classical notions" of "does this really" progress or have gravity, motion to this place?. Progressions that do odd things could probably have classifications as "ellisions" and the like but with enough oddities it's probably not even worth it to try to reel into a "harmonic world" that it doesn't belong to.

    BTW--The sonic explanation or "reeled in" classic harmonic analysis ;) of your above progression (at least to my ears) is a IV-I variant and your tune is in D starting on IV. G Go is a sub for A7(b9) which goes to D. Your Do is a variant on Ab7b5 which cycles back to G. Stick in the Ab below the Do chord sometime and you'll hear what I'm talking about. This is assuming ofcourse that this chord progression cycles back to where it started (G)
  13. ryco


    Apr 24, 2005
    I thought I understood a fully diminished chord to be R, M2, m3, P4, d5, double flat 7 -a major 6 enharmonically but not theoretically; that's what gave the chord it's designation as fully diminished - to octave. I believe this to be the scale I learned in college theory (way back when). We studied out of "Harmony" by Walter Piston

    Learning out of Ray Brown's Bass Method I was taught to play the M7 in diminished runs. A lot of times the M7 was put in brackets which gave me the impression it was the prefered tone, but it was more implied than acknowledged (does that even make sense??) because the 7th degree was already filled. I had no problem throwing out the 6th altogether because - well, it was done a long time ago by guys wearing powdered wigs.

    It was to resolve this confusion I was having when I first posted. What helps my clarity is to call the M6 a bb7 because that's what it is. Hey - Ray calls it a M6 too and I understand scoring it as such for ease of reading - especially when sight reading. But as far as theory and function I was wondering if this was puzzling anyone else.

    I apologize for sounding flippant when calling the Diminished 8 tone scale (WHWHWHWH) and the C7b9 (HWHWHWHW) scales anomalies. They are very much a part of the jazz (or modern music) language as is the C7+9 (or "Altered" or Pomeroy or Diminished Whole Tone - whatever you want to call it). And, along with the Locrian scale/chord, are so often used I have no problem understanding their location, use and resolutions. This post was more about understanding the fully diminished scale because I so rarely hear/see it used. Heck, half-dims are everywhere!

    Thanks to all for excellent explanations and the theory lessons!

    ps> the V9 was referring to the full dim scale