•••Vagrant Chords and other Curiosities•••

[Bill Robinson]

•••When I was in first year theory, we were studying the VIIth scale degree and its chord, the diminished triad B-D-F. My ear never bought into the diminished chord built on VII; it sounded like an incomplete V chord to me (key of C: B-D-F, an incomplete G7 chord.•••• Later, when I read Schoenberg's "Harmonielehre" text, and also Piston's "Harmony", they confirmed my ear: they treated the resolution of the diminished seventh on VII by imagining a root tone a major third below, and resolving it as a V chord (maj third below B is G).•••• Later, when dim. 7th chords came up, I offered that they relate to flat 9 chords; take any diminished 7th, add a non-chord diminished scale tone, and you have a dominant flat 9. The theory teacher, K. Hoppe, would have none of this, and dismissed my contribution because this changed the root function. I got this idea from a Dan Haerle book!•••• Guitarists: use this! You know one or two dim 7th forms; use them as flat 9's whenever that chord comes up in a lead sheet. It'll be one of three adjacent frets for whatever dim 7th form you choose! •••• By the way, I first heard of lowering a tone of a dim 7th to get a dom 7th not from Pat Martino...but from Schoenberg in the Harmonielehre text! He is my hero; he knew tonality inside out before he discarded it! The Harmonielehre is available as a softcover book now, so there's no excuse for you jazzers not to get a copy of it. Schoenberg called the dim 7ths "vagrant" chords. The Tone Police: "Alright, you diminished 7ths either resolve or leave town; but we can't have you hanging around here any longer!" A friend of mine thought that "vagrant chords" was a really humorous concept; and I guess ol' Arnold DID have a sense of humor!

[bassist]

there is a school of theorists who use something called "basse fundamentale" (that's french for "fundamental bass"). my teacher (Gerald Levinson), who studied at paris conservatory teaches us using the basse fundamentale way of looking at things. the basse fundamentale is more based on function than anything else... so, since a G7 and a Bdim7 are both dominant functions in the key of C, they are, in a sense, fundamentally both G chords... so each of them have a basse fundamentale of G. also, as another example, augmented sixth chords function as secondary dominants, so their basse fundamentale is scale degree two.
when we analyze a piece of music, we print an extra empty bass staff under each staff, and at every harmony change, we write in the basse fundamentale. it makes VERY clear (visually) the underlying progression at all times.

also, basse fundamentale accounts for voice leading. using the example of a Bdim7th chord... each note should move as it would if you think of it as a G7 chord. the B is the leading tone, so that resolves upwards. the d is the 5th of the G7, so it is NOT a "tendency tone". it is the only note in a diminished 7th that can resolve wherever it wants (but we will get to what is best in a second). the F is the 7th of a G7, so that resolves down. and the Ab is the 9th of a G7, so that resolves down as well. now, the D can either go down to a C or up to an E. (assuming we are in C major, not minor). either of these is acceptable as a resolution. going to a C presents a bit of a problem... diminished 5th to perfect 5th (D-Ab... C-G). and the other resolution presents another minor issue... doubling the third of the tonic (when the chord resolves). to my ears, the latter is less of an issue, so i usually go with the doubled third instead of the D5-P5.

anyways, you can use the same logic to explain the voiceleading of augmented 6th chords (thinking of them as functioning in accordance with their "basse fundamentale" function).

dan

[Bill Robinson]

•••Thanks for the info, Bassist. As a bassist you can appreciate the importance of root function.••• I read some of yours & Ed Byrne's postings on the chord substitution question. I tried to give the simplest answer possible to that poor overwhelmed guy who asked it (it was something I myself pondered for several years before getting a real grip on it). It seems to me that the main difference between academic theory & jazz theory is that jazz theory will give you info that can be put to use in musical craft/performance, whereas academic theory tends to be a historically-oriented exposition of common practice derived from already existing examples. Of course, there are exceptions to these gross generalisations, For instance, the derivation of flat 9s from diminished 7ths is more a method for creation of new forms than it is an exposition of any pre-existing practice. My theory teacher couldn't accept this correlation because it changed her root function. But the other jazzer in class dug what i was saying (and he was writing his own horn arrangements to be played by our ensemble).••• I have learned a lot from the likes of Dan Haerle; I hate to hear jazz teachers put into a second-class citizen category. And when Haerle came to our little junior college and performed, and I was confronted with his brilliant piano playing, I knew then that I was on the right track: never again would I let any academic keep me from seeing the essential musical truth. I still have the jazz theory ring-binder book he signed for me; "Good luck and keep on working."

[Jakeweiser]

That's the great thing about Dan Haerle's books and his style is that he's really mastered the approach he's developed to teaching. I wish I could have gotten a chance to have studied with him while I've been here at North TExas, but allas it is not meant to be. Either way, all those people who got to work with him on doubt got a lot out of him.

I commonly recommend his Jazz Language book to people looking for a theory book and already have or dislike Levines book. I think it's very straight forward and to the point without dancing around issues, leaving it up to the student to find a way to put it to practice, very little spoon feeding etc.

As for G7 and Bdim being the same chord... essentially they share the same function, obviously. HOwever aren't the same chord. The leading tone whiches to resolve in a key such as C, sure. Bdiminished is far more flexible as a passing chord since it is essentially 3 chords (4 chords fully diminished) at the same time, lending itself to resolve elsewhere.

It's always interesting to me when I go back and read lessons from the past when it was put to me that there are 3 sounds, Major, Minor and Dominant. It's a good way to initially grasp those basic groupings, yet is a bit narrow eared I suppose. In the end it probably stunted my growth at the start, but whatever ;). Lumped in tha Dominant sound category was, obviously Diminished. Dominant being short hand for "needing to resolve"

[playground]

•••When I was in first year theory, we were studying the VIIth scale degree and its chord, the diminished triad B-D-F. My ear never bought into the diminished chord built on VII; it sounded like an incomplete V chord to me (key of C: B-D-F, an incomplete G7 chord.••••

so, since a G7 and a Bdim7 are both dominant functions in the key of C, they are, in a sense, fundamentally both G chords... so each of them have a basse fundamentale of G.

using the example of a Bdim7th chord... and the Ab is the 9th of a G7, so that resolves down as well.

you guys are awesome!!! but i'm confused about something. in bill's post he seems to be talking about C Major harmony where the chord built on B (7th scale degree) is what i've come to think of 'half-diminished' - because diatonically there's no natural 6th, right? and then in bassist's post he seems to be talking about that chord as 'fully diminished' (the Ab note being there). i'm just confused. you guys aren't reducing these two chord types down to the same thing right?

[Jakeweiser]

Bill is looking at it originally just in form of Triads, thus the triad built of the 7th scale degree is a diminished Triad.

Bassist is harmonizing it stacking the 3rds to get 4 note chords, thus now the 7th scale degree is half diminished, more so because it has a minor 7th from the root rather then a major 6th from it. A Diminished Chord, fully diminished is 4 minor 3rds stacked upon it, common thought as 1, b3, b5 and bb7 (double flat) but many enharmonically spell that as 6. Half diminished chords can have flat and natural 13ths depending on your choice of harmonization, personal taste in tension and of course functional listening at the moment.

Typically in Classical Theory the beginning stages of learning it is very triadic, I is major not major7, V is major not Dominant, although named Dominiant due to function of the leading tone. In "Jazz Theory" many are taught early on to only think about the 7th chords in harmonization of the scales and ignore triads as a whole until later. We see IM7 iim7 iiim7 IVM7 V7 vim7 viim7b5 for a Major Scale harmonization, rather then I ii iii IV V vi viidim

Thus important to learn both, because it really can help with your sub vocabulary

The Bdim7 thing is just a sub for G7 in common language, and overtly common in Jazz that a Dominant Chord can be subbed for a Diminished chord based on the b9 or it's Major 3rd. It's just a way to stretch it out more.

[LDGuy]

I did the Aebersold course under Haerle (not the combo, I wasn't good enough, he took the top one, but I went to his musicianship class) and I seem to recall him introducing the dim7 / b9 concept. It's true, it changes the root of the chord, but actually a diminished 7th is a strange chord as often the root doesn't really matter (or perhaps importance of the written root is negligable). There are only three dim7 chords, and as long as the percieved root of the dim7 is in the correct sequence*, then the dim7 will perform its desired function.

Consider the sequence:

C / Bdim7 / | Amin / / /

Note that if the first two chords are in root position, the most logical voicing for the Amin would be in root also. However, you could play:

C(/G) / Abdim7 / | Amin / / /

Note that the Abdim7 performs exactly the same function as the Bdim7. This might be crucial in orchesteral writing - for example the strings might play a triadic progression C-Bdim-Amin, but the brass might creep up G-Ab-A. So is the diminished chord a Bdim or an Abdim? Is it a Bdim/Ab? (Which is a crazy chord symbol if ever I saw one!)

So in conclusion, it doesn't really hold any odds to say that making a b9 of a diminished chord negates the root, because dimished chords have no root (or an infinite number of roots!).

L.
_________
*The sequences are
C-Eb-Gb-A-C etc.
Db-E-G-Bb-Db etc.
D-F-Ab-B-D etc.

[bossman]

I did the Aebersold course under Haerle (not the combo, I wasn't good enough, he took the top one, but I went to his musicianship class) and I seem to recall him introducing the dim7 / b9 concept. It's true, it changes the root of the chord, but actually a diminished 7th is a strange chord as often the root doesn't really matter (or perhaps importance of the written root is negligable). There are only three dim7 chords, and as long as the percieved root of the dim7 is in the correct sequence*, then the dim7 will perform its desired function.

Consider the sequence:

C / Bdim7 / | Amin / / /

Note that if the first two chords are in root position, the most logical voicing for the Amin would be in root also. However, you could play:

C(/G) / Abdim7 / | Amin / / /

Note that the Abdim7 performs exactly the same function as the Bdim7. This might be crucial in orchesteral writing - for example the strings might play a triadic progression C-Bdim-Amin, but the brass might creep up G-Ab-A. So is the diminished chord a Bdim or an Abdim? Is it a Bdim/Ab? (Which is a crazy chord symbol if ever I saw one!)

So in conclusion, it doesn't really hold any odds to say that making a b9 of a diminished chord negates the root, because dimished chords have no root (or an infinite number of roots!).

L.
_________
*The sequences are
C-Eb-Gb-A-C etc.
Db-E-G-Bb-Db etc.
D-F-Ab-B-D etc.

If we're in C though, wouldn't your second example ( C/G, Abdim7, Am ) sound strange? C/G sounds like a Dominant with the leading tone and 5th suspended from the previous chord. I believe this is called a Cadential 6-4 and is commonly used coming from a pre-dominant at a cadence. For example, in Bach-style 4-part chorale:

ii7 - V64-53-I
C - C----B--C
F - E----D--E
A - G-------G
D - G-------C

To my ears, in a classical setting. C/G in the key of C sounds like a dominant, or at least like a dominant is coming on the upbeat or something.

[Phil Kelly]

AS many of you here know by now, I have a great interest in the many characteristics present in the diminished pitch set and the scales and chordal relationships generated by it.

In addition to the basic "linking" functions diminished chords provide in harmonizing nonchordal tones in a linear progression, the basic diminished chord
( B D F G# ( Ab ) ) is also functional as a dominant structure with the "implied" bass notes ( also in diminished series )

G G79b
E E79b
Db Db79b
Bb Bb79b

each one with it's own set of resolutions available thru voice leading.

Another pitch set derived from this phenomena that operates in a similar mobile way is what I call the
"altered drop 2 " shape built on a second inversion major triad with an added tritone below. ( hello guitar guys ..this is a real characteristic Jim Hall shape! )

F B E G# ..which then can be easily moved in parallel
F B E G# >Ab D G B > B F Bb D > D F Ab Db etc

..over the same set of "implied" bass notes as previously:


G G79b
E E79b
Db Db79b
Bb Bb79b

And: since its all based upon a diminished pitch class, you only need to learn three versions of this to cover all possible chromatic situations!!

:gavel: :cheers :gavel: :cheers :gavel: :cheers

[Jay Norem]

This is fascinating stuff to read, and I'm wondering if any of you can give examples of where I might actually hear what you're talking about on jazz recordings. Would they, for example, appear on a Monk record (I've got just about all of them) or, say, the Bird stuff or Saxophone Colosus or Milestones or something like that? (I'm more of an ear guy, you see, I either unlearned or forgot most of the harmonic-theory I was taught in school.) I hope this doesn't seem like a stupid thing to ask.

[Phil Kelly]

This is fascinating stuff to read, and I'm wondering if any of you can give examples of where I might actually hear what you're talking about on jazz recordings. Would they, for example, appear on a Monk record (I've got just about all of them) or, say, the Bird stuff or Saxophone Colosus or Milestones or something like that? (I'm more of an ear guy, you see, I either unlearned or forgot most of the harmonic-theory I was taught in school.) I hope this doesn't seem like a stupid thing to ask.


Jay:

Go here ..I just posted an mp3 and a PDF illustration of my last post.

http://www.freejazzinstitute.org/uploads/20070706122914_graypencil.pdf

[LDGuy]

If we're in C though, wouldn't your second example ( C/G, Abdim7, Am ) sound strange? C/G sounds like a Dominant with the leading tone and 5th suspended from the previous chord. I believe this is called a Cadential 6-4 and is commonly used coming from a pre-dominant at a cadence. For example, in Bach-style 4-part chorale:

ii7 - V64-53-I
C - C----B--C
F - E----D--E
A - G-------G
D - G-------C

To my ears, in a classical setting. C/G in the key of C sounds like a dominant, or at least like a dominant is coming on the upbeat or something.

I'm not too sure what you mean. Anyway, here's an audio file of the sort of orchesteral arrangement I was thinking of, and you're right, it does form part of a cadencial 64 sequence.

http://www.wikiupload.com/download_page.php?id=173573

L.

[bossman]

I'm not too sure what you mean. Anyway, here's an audio file of the sort of orchesteral arrangement I was thinking of, and you're right, it does form part of a cadencial sequence.

http://www.wikiupload.com/download_page.php?id=173573

L.

Hmm I definitely would treat that middle chord as a first inversion tonicization of the following chord. It appears to be I [V6] ii V64 I, to my ears. It might be [vii] instead of [V6] though.

[bassist]

you guys are awesome!!! but i'm confused about something. in bill's post he seems to be talking about C Major harmony where the chord built on B (7th scale degree) is what i've come to think of 'half-diminished' - because diatonically there's no natural 6th, right? and then in bassist's post he seems to be talking about that chord as 'fully diminished' (the Ab note being there). i'm just confused. you guys aren't reducing these two chord types down to the same thing right?

sorry sorry sorry... i shouldn't have simplified things the way i did. i guess i sort of skipped a step, which could make things really confusing.
yeah, in C major, the diatonic 7th chord built on the leading tone is a half diminished chord (as it is in all major keys). in minor keys, the 7th chord built on the leading tone is a fully diminished 7th chord.
"modal mixture" (which is borrowing chords from one mode in the other mode... i.e. a minor iv chord in the major) became increasingly popular over the course of the evolution of classical music. one very common usage of mixture is to increase the tension of a leading tone in the major by using a fully diminished 7th instead of a half diminished 7th. play C maj - Bhalfdim.7 - C maj and C maj - B dim 7 - C maj on piano, and you'll hear the difference. so, yeah, people began to substitute these and put the fully diminished 7th in the major. by the romantic period, this instance of mixture was VERY common... it was sort of expected that if you were using a leading tone chord, it would be a fully diminished 7th.
anyways, that was the mindset i was working in... i shoudl have mentioned that it is NOT the diatonic leading tone chord in the major.

thanks!
dan

[LDGuy]

Hmm I definitely would treat that middle chord as a first inversion tonicization of the following chord. It appears to be I [V6] ii V64 I, to my ears. It might be [vii] instead of [V6] though.

I'm not sure I'm quite with you here, can you explain in more detail?

L.

[bassist]

p.s... everythign that i said still works with half-diminished 7th chords. the 7th still functions as the 9th of a dominant chord, so it still must resolve downwards. this means, however, that the D (the 5th of the dominant, the third of the L.T. chord) MUST resolve up to avoid parallel perfect 5ths. you no longer have the option for it to resolve down.
but yeah, you can still think of the voice leading of a half-dim. 7th chord as if it was a sort of dominant. i.e... the basse fundamentale of any leading tone chord is scale degree 5.

dan

[bossman]

I'm not sure I'm quite with you here, can you explain in more detail?

L.

The square brackets mean "this chord OF the following chord" so for example in the key of C major:

I [V7] V is C-D7-G (D7 is the V7 of the G.)

The thing you showed me sounds like I [V6] ii V64 I, which is:

C, A7/C# OR C#dim7 (i havent listened closely enough), Dmin, C/G, C

edit: V64 means Cadential 6-4, it is a way of delaying the dominant. It is commonly used coming from a pre-dominant, so for example:

Dmin-C/G-G-C

The G in the bass is strong enough to suggest dominant, especially when coming from a pre-dominant. Usually the notes C and E will change to B and D or B and F, and then resolve to C major.

edit2: I made a midi of the sound of a cadential 6-4. It is Dm-C/G G7-C: Here. (http://qquintet.com/64.mid)

[LDGuy]

The square brackets mean "this chord OF the following chord" so for example in the key of C major:

I [V7] V is C-D7-G (D7 is the V7 of the G.)

The thing you showed me sounds like I [V6] ii V64 I, which is:

C, A7/C# OR C#dim7 (i havent listened closely enough), Dmin, C/G, C

edit: V64 means Cadential 6-4, it is a way of delaying the dominant. It is commonly used coming from a pre-dominant, so for example:

Dmin-C/G-G-C

The G in the bass is strong enough to suggest dominant, especially when coming from a pre-dominant. Usually the notes C and E will change to B and D or B and F, and then resolve to C major.

edit2: I made a midi of the sound of a cadential 6-4. It is Dm-C/G G7-C: Here. (http://qquintet.com/64.mid)

The square bracket notation is the thing I didn't quite understand.

I know about cadencial 64's, and although Ic is a strong indication of a perfect cadence to follow, the movement here is also a logical cadencial extension. In this case - C/G / G#dim7 / | Amin - the G leads to the G#, the rest of the chord leading down triadically. This, as you say, delays the dominant, and the cadence is extended.

So in your notation it would appear:

Ic [vii] vi IV Ic V7 I

The point I was making originally (check back to page one) is that it doesn't matter whether the second chord has brackets or not - both diminished 7ths perform the same function, even if their percieved roots are different.

L.

[Bill Robinson]

Aren't we lucky to have this great resource? I have lately begun to "lose faith" in the diminished chord as a free-standing separate entity. It may just be an illusion, like those picket-fence moiré patterns you see in people's front yards as you drive down the street. There it is; you see it; but does it really exist? Or is the diminished chord simply an "interference pattern", the result of voice movement from one place to another? That diminished fifth interval is mighty shakey sounding, not at all stable. And you can invert it, too. Where's the security in that? This leads me back to the diminished and whole-tone scales; they are the symmetrical division of the chromatic scale into its component parts: minor seconds gives you the chromatic scale, major seconds gives you the whole-tone scale, minor thirds gives you diminished sevenths, the diminished whole/half or half/whole scales are a combination of wholetones, chromatic steps, and minor thirds (not to mention the tritone)...but when you hit the major third, the symmetry goes away, unless you circle back through the octave...as do fourths and fifths. The tritone is the perfect division, once again symmetrical.••• The diminished seventh chord, and the inherent difficulties in spelling it and defining its root function reveal the "crack" in our diatonic, seven-letter-name music spelling system. Like that "aha" moment when you see that the Wizard of Oz is just a guy operating a machine.

[playground]

sorry sorry sorry... i shouldn't have simplified things the way i did. i guess i sort of skipped a step, which could make things really confusing.
yeah, in C major, the diatonic 7th chord built on the leading tone is a half diminished chord (as it is in all major keys). in minor keys, the 7th chord built on the leading tone is a fully diminished 7th chord.
"modal mixture" (which is borrowing chords from one mode in the other mode... i.e. a minor iv chord in the major) became increasingly popular over the course of the evolution of classical music. one very common usage of mixture is to increase the tension of a leading tone in the major by using a fully diminished 7th instead of a half diminished 7th. play C maj - Bhalfdim.7 - C maj and C maj - B dim 7 - C maj on piano, and you'll hear the difference. so, yeah, people began to substitute these and put the fully diminished 7th in the major. by the romantic period, this instance of mixture was VERY common... it was sort of expected that if you were using a leading tone chord, it would be a fully diminished 7th.
anyways, that was the mindset i was working in... i shoudl have mentioned that it is NOT the diatonic leading tone chord in the major.

thanks!
dan

cool man. thanks. i hadn't heard of that before and will try playing through those sounds. i'd heard of something that's maybe similar: the manipulation of minor key harmony into harmonic minor w/ the purpose of creating a V7 chord. changing that one note (aeolian to harmonic, b7th to nat.7th) inserted the leading tone into the tonality and also gave the V chord it's dominant quality instead of a straight minor 7th. or something like that. not really too sure on that stuff. it's all a little hazy and i may be remembering that stuff wrong.

but anyway, thanks bassist!

[Slant]

•••Wow, this is neat! I'm relatively new to the internet, and it's wonderful to see a little pebble you toss in create such ripples! "Thanks" to all of you wonderful musical thinkers out there. Aren't we lucky to have this great resource?

Yes, I agree 100%!!


I started thinking about why a keyboard is designed the way it is (after reading Pat Martino's Creative Force books). It seems obvious to me now; the 7-note diatonic scale. It's weird the way the white notes "discard" the left-over pentatonic black notes.

I always considered the "design" of the keyboard to be simply symptomatic of the layout of the strings "underneath the hood". There are very real vibratory relationships expressed between the strings due to their length variation and, obviously, relative tensions. These relationships can be expressed numerically, and thus we can also give them names. The layout of the keys is simply representative of those relationships. The keys really mean nothing beyond the HOW of the making of the sound.

We should all bear in mind at all times that everything in music is circular (despite the linear appearance of the keyboard!!). Take a simple example/experiment: draw up a table (in Excel or some other worksheet program) that you might call the "interval matrix" . On axis X you will list, in succession, different intervals from diminshed 2nds through augmented 8ths, and then do the same on axis Y. Then, inside the matrix list the number of half steps from any given interval to another. When done start taking note of the order/patterns that exist within the apparent chaos -- you will notice that it is a circular pattern, much like ripples on a calm pond after dropping in a rock.

I think everyone here (myself included) tends to become "spellbound" by the multitude of terms employed in "music theory". We should remember that: 1. it's really just a common language (and a loose one at that!) applied to musical pieces after the fact (or should be, anyway), and 2. since everything is in constant flux, the language we use will necessarily have to change with it. Theory is an "applied science" and in no way sets limits on what notes can be used with other notes, etc. My argument is this: let's try, as much as we can, when composing, to forget the theory that's been crammed into our heads. Toss it out. Play what moves you! Play something that makes a statement to you. Play something that makes you say, "yeah, that's the sh**"!! PLAY LIKE YOU ARE USING FIGURES OF SPEECH!! Seriously, how often do you use the EXACT words that are on your mind? If you're like me you use figures, and they are often much more colorful and to the point if the listener has the "ears to hear".

After you've played something that moves you...then write it out; then do the analysis. If there's something there that defies analysis...well...either you don't have a "full vocabulary" or you've just done some damn fine creating (if it works, that is)!

At the root of most "theory" is the idea that there is some natural law underlying what sounds "right" or "correct" or "pleasing to the ear". Maybe that's true, but I'd much rather walk my own line than answer to centuries of dogmatic rules and regulations. They're there, yeah. They have their place. So what?

[Bill Robinson]

••• I'm trying to think of some jazz examples of some of this stuff we've been discussing. An example that comes to mind is the tune "Song Bird" by Pat Martino off of "Joyous Lake" ("Joyous Lake" and "Starbright" are now available as a two-fer CD on Collectibles label). In this tune Martino solos over altered dominants, and the song is structured around flat-nine chords, so you can get a taste of what these chords sound like. I love the sound of altered dominants, and having started out by playing blues music, I feel right at home in the presence of flatted sevenths. They sound more natural to me than the "leading tone" regular major seventh. Ever notice how even in a I chord in blues, the 7th is flatted?

[edrowland]

Coming into this thread a bit late.... but I wonder if you could help me with a bit of theory to back something I'm doing over the fretboard. Both Jake and Phil touched on it. And i've been meaning to dig into it and figure out what's going on for a while now.

What follows is my impression from playing rather than anything based on theory that I've been taught. If somebody could throw me a theoretical hook or two around which I can explore, I'd be grateful.

Truth be told, pure naked full diminished chords don't always sit comfortably with my ears. My impression from playing is that full diminished chords tend to show up in older tunes from the 30s and 40s, in a way that's uncommon in more modern tunes. (I think of them as occuring in arrangements that have a lot of 6 chords as well, for some reason). In more modern tunes, I don't have much trouble with dim7s that really are purely passing chords, or dim7s that have been explicitly written a 7b9. My impression is that there's a trend toward "ways to play dim7 without really playing it".

I've found two ways of dressing up dim7s in a way that makes me much more confortable with them. One is the 7b9 substitution. I'm not sure why this makes me feel so much more comfortable, but it does. Perhaps the extra implied root allows me to think more in terms of dominant chords, and alts (which is a sound that does sit much more easily with me). Anyway. I'm not too worried about that approach. I more-or-less understand what I'm doing and why.

The other way I deal with it is something that I don't really have a handle on. The voicing that I use often is:

Bdim7 = B root, Ab D G

The things that made me ask: Jake mentioned use of 6ths (major or minor) as extensions to the dim7, and that's what that voicing is: a b13 added to to a Bdim7. And Phil mentioned the "Jim Hall" voicing, which is along the same lines as this voicing (it's an inversion of this voicing). I know *why* i like this voicing: the rub of the Ab against the G is just plain nice, and my gut impression (unconfirmed) is that it voice leads nicely into related 13 chords. For some reason, having the b13 in there just makes it seem all ok again (both from a comping and a soloing point of view). But, fundamentally, I do it because it sounds nice with no real understanding of why.

Maybe it's just a very simple thing: b13 *is* a natural extension of dim7. But I can't help thinking I'm leaving something important on the table here.