Theory question! Diminished chords

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This may be a strange question, but I have a chord sequence that "works" (i.e., it's what I hear in my head) but I want to understand *why* it works, and I'm realizing I have kind of a hole in my theory knowledge about diminished (seventh) chords. I'll post the whole sequence here, but it's specially the F#o7 I'm wondering about.

(one measure per chord)
C B7 E7 E7
Am E7 Am Am
F F#o7 C A7
D7 G7 C G7

Where F#o7 = F# A C D# (and any of those notes could be heard as the root).

So the question is, why does it work? I know the general answer is "voice leading," but I'm looking for a more specific sense of how that F - F#o7 - C sequence works. It feels like a kind of Tin Pan Alley progression--how did the classic songwriters use diminished chords? Looking at @nancyrost, @izaak, and other theory-smart people. Thanks!

This paragraph comes from The Everything Music theory book by Marc Schonbrun

In jazz, all dominant chord extensions take their notes from the Mixolydian scale built off the root. An E13th chord will take all its notes from the E Mixolydian scale. this is important because the spelling of the individual notes has to follow the home scale or the chord won't sound right. In jaz, the home scale for dominant chords is the Mixolydian mode, not the major scale (that's reserved for major seventh chords). this is another example of modal use in jazz.

Not sure if that's what you're asking, but hope it helps.

There was a time that I could answer this confidently without having to think about it, but I've lost a lot of my theory knowledge. Without playing through the progression and thinking too much on it, I'd say it was probably the C. It's present in all three chords and acts as a sort of pivot.

Hmm, [@brrrse], I'm not seeing the connection, but thanks for that!

By the way, I know the IV - iv#o - I progression (which is what I have above) is common, just not sure why/hpw it works.

I was thinking maybe it was because of the mode rules for diminished chords. Good luck!

If you don't get a definitive answer by tonight, I'll go upstairs and grab my old theory book.

from the line before, a c e goes to F A C with one half-step motion, then F A C has only to sharp one note and add a tone to go to F# A C D#, which goes easily to G C E because the C remains and the F# goes to G, the D# to E in parallel ascending thirds by halfstep, as if a suspension had been resolved. even if the A were held, it would be C6 chord, which implies its own relative minor as a 7th chord and is stable. the A note in the diminished chord also resolves a whole step down to G, which adds to the finality of the diminished resolving. i look at the movement of the notes involved instead of learning that this is vii#o resolving to IV in the key of G, if that is what it is as it changes key to G from the C/amin center you had before. clear as mud?

Nice progression, @downburst !!! This is very jazzy of you. I sing barber-shop quartets with a group of singers here in Utah, and we see this kind of progression all the time. It is surprisingly easy to sing because of the ascending half steps: while somebody (like the lead) belts a C through all three chords, someone sings F to F# to G , someone sings A to A to Bb (the C7 wasn't in your progression, but probably could be), and someone gets the descending whole step (also easy to sing) before their ascending half step so: F to D# to E... and there you have it. The diminished chord sort of acts as a chromatic passing chord between the F and C. For us guitarists, it is easy to forget about the individual notes in a chord, because we often leave some out by necessity and just imply them by the overall context. The common tone, C, really unifies the three chords and gives the other voices something to tune to. If you think of ways you might use a chromatic note in a melody--- passing tone, neighbor tone, leading tone, etc--- you can often find diminished chords being used the same way, it's just that more voices are involved.

Thanks, those are great explanations, and what I meant by voice leading in my original post. I agree, guitarists tend to think in terms of chord-to-chord movement, and that only gets you so far. I'm used to the voice leading way of thinking about how, say, a V7 resolves to I, I just couldn't extend it to this case.

A couple other things about it are interesting. One is that the o7 chord has two overlapping tritones in it, which both go away when it resolves--a lot of tension is dissipated there. The other is that the F#o7 is almost the same as a B7 chord, except for the B/C difference, which means I don't know what. Maybe that I can "cheat" as a guitarist, since I have touble playing diminished chords.

Thanks for a great discussion!

[email protected] is not only a note away from B7, it's also one note away from Ab7, F7 and D7. Makes good glue.

The notes that change from F#o7 to C (major7) go up a half-step. The first two notes of F#o7 (F# and A ) are the third and fifth of D, which is the V of G, the V of Cmajor.
So you get a V of V sounding movement of the D chord to the G going down, and the chromatic steps going up from F#o7 going to C, the Root/starting chord of the progression. Since the V of V changes happen so often in the progression, your ear hears that, even when some of the notes are missing or implied (like the root note of the D chord (D F# A), where the third and fifth are the root and third of F#o7. That's my thought.

Cadence, --

Among other, took it, liked it... Dr. Zack Moir ... very patient, proacive individual there, surprisingly in such a free course -- is present. (Unlike, non-present "mentors" in coursera courses --questioning usefulness.) When I took it, they were still working out the bugs, and still may be. It's built upon a European standard of, levels, grades you might want to look into first, --too.

In my noodling... I always, pick a 3rd in a chord and use it as a root, to "next"... or rather, see why it worked since, hear first, then seek to "write it down" ... key, what key? There's no key... Smile ... --no, not a jazz guy, but "Bass-ed" to a few who wondered how they didn't loose me (on purpose, attempts), -- in 5+ key changes... from no root, for long anyway... --not fun, every night, but, once in a while.

Many songs in "history", were "written" from chord-fragments, noodling first, then, --back pedaled to "what it was". E.g. "Horse with no name", America (comes to mind, if, if remembering correctly... ) as a "pop" example.

I consider on a Guitar neck, Bass/Treble, am usually only one Note away from being "correct", if fast enough in my passing tones.

Ok then that (F#dim 7th) works out to be a (back door) dominant for the C major triad in bar 11, because if reconfigured by inversion it would be a (C diminished 7th).

Try it... Play the (C dim7th) followed by the C major triad. It's a way of ending a song, instead of using the G7-C major. It's called a back door. There are several back doors. Another one would be (B7-C major), which is almost the same notes, as the (Cdim7th).

Over all this progression is continuously changing keys, and uses at least 4 methods of changing key within a song. yet never really gets lost, because of the heavy use of (dominant 7th) chords, and the (circle of fifths) progressions. This is a beautiful chord progression, and if you are into jazz, it makes perfect sense.

I've played a piano solo over the top of this, and Posted it as a song on my page, so you can hear how it works out.
Listen Here: *17784

And of course I have made @downburst my collab.

Thanks buddy. Dirol


The unexpected chord, especially a diminished chord, gives lots of options for where to go next.

Sure sounds prettier than when I play it! Smile

This is fascinating, and I love that sequence! Smile

@downburst - I think you're going to have a few collabs from this, because I've got an idea forming now that I've played through it.

Well diminished 7s usually work in one of 2 ways - as secondary dominants ( viio7 of a chord- like if you had gone F#o7 to G major/minor) or embellishing chords where they temporarily delay the arrival of the expected chord tones. This means they need to share a root with the chord you're going to - in this case C- so the D# is an accented dissonance leading to the E the F# and A to the G - strong voice-leading over stable root. I t was popular in early tin-pan ally songs - in fact Gershwin has that exact progression in "I got rhythm" ...that's my take at least

I've done this with the progression - *17904

I just want to unhelpfully chime in and say that I'm too dumb to understand what any of you are talking about! Smile

I'm quite jealous of the musical knowledge on display here, though. I wish I had the discipline to learn some formal music theory!

I'd like to say thank you for asking your question and I'm so glad I stuck around and read all the answers, because I have learned a lot. Smile

@Deaf Steever I picked up "Music Theory for Dummies" and "Music Composition for Dummies" after FAWM ended, to brush up my musical skills a little. They are great resources for this sort of thing! Haven't seen them at McNally Robinson or anything but and exist for a reason, I suppose... Wink

@metalfoot, Thanks for the book recommendations! I'll definitely check out both titles. I just placed requests for them (I work at the library!).