Functional difference between dom7b9 and diminished?

[Reg]

Hey Bud.....

The main difference with most jazz players... is the 5th.

C7b9 implies just what is says... C E G Bb Db Rt, 3rd, 5th, b7th and a b9th
Cdim7 implies ......................... C Eb Gb Bbb

Function would need to be referenced from the Tune, by that I mean you would make an analysis which would reflect how the harmony works.... which chords have what function and how they all harmonically relate to each other.

When you move from traditional vanilla functional harmony.... to jazz harmony, it can become more complicated because the musical guidelines which define how Function works in musical contexts... tunes and performance, expands and can have more layers of Functional guidelines going on at the same time. Typically Modal, which creates different guidelines as to how notes react to each other and which notes are the references for control of movement...(Function), and the use of Blue Notes and MM are most common.

I could go on... but who really cares.

[AlsoRan]

Reg, Pingu, and Christian,

You just made me realize that just because you have the notes of, for example, a CMaj7 chord, it does not necessarily mean you get that CMaj7 "sound." Forgive me, but this is a bit of an epiphany for me. I never considered that different inversions might suggest other tonalities/functionality, just because of the order in which the notes are played in a given progression.

No wonder some of the chords that I created for my personal songs sucked. It is apparently, not just about the notes.

[ragman1]

It's all about context, as usual. A very popular example that often comes up here is a mb6 chord. Everyone wonders what the hell that is - and how to play it - till it's explained that it's just an inverted M7.

E.g.

Play Cm6 - 8x788x

Drop the m6 note a fret to get Cmb6 - 8x688x

And you have an AbM7/C.

But in context it is a mb6, not an AbM7.

It's in Iris, at the bottom:

[AlsoRan]

It's all about context, as usual. A very popular example that often comes up here is a mb6 chord. Everyone wonders what the hell that is - and how to play it - till it's explained that it's just an inverted M7.

E.g.

Play Cm6 - 8x788x

Drop the m6 note a fret to get Cmb6 - 8x688x

And you have an AbM7/C.

But in context it is a mb6, not an AbM7.

It's in Iris, at the bottom:

Great example!!

[Reg]

Rag... context is still just part of what we're talking about. Context needs a Reference....and references can totally change how ones hears and plays any context.

The difficulties with learning how to recognize, both contexts and references, is to become aware of what they are... or with jazz performance.... what they can become.

One of the simple tricks..(skills), is to become aware and learn how to use Harmony in the same way one can learn how to use rhythm to create those feels of being in the pocket, groove or locked in etc...

Most just say... he or she has great "feel", big ears etc... But generally all that is going on is ...just as jazz players (at least most), use rhythm to create accent patterns that repeat... or create the perception of repeat to naturally have Targets or musically organized points in time that have more musical importance within a FORM, and have musical relationships within themselves.

They also use that musical Formula with Harmony and single notes....
I'm not trying to get into the harmony or melody thing.... But single notes also have harmonic references....they imply harmony. Anyway using harmony and notes with similar musical organization derived from rhythmic organization.... is part of performing in a Jazz style. Again the difficult aspect is being aware of what's going on as well as what could be going on. It's generally why I've always pushed the ... Get your technique together.

Typically with Shorter ... as in Iris Db-b6 is just simple modal reference... Natural Minor. Which would imply the Harmonic Starting reference for playing. Most jazz players don't just play Db-b6 over and over.... we create Chord Patterns and use the concepts mentioned above for musical organization in creating those chord patterns.... or just use the established common practice... chord licks with harmonic implications.

[pauln]

I tend to "resolve" distinguishing between the two by changing the dom7b9 to 7sus4b5.

To hear why, take the last seven changes of SBSL as an example.

E7dim G7dim D7dim F7dim C7dim Eb7dim Bbmaj7

E7b9 G7b9 DBb9 F7b9 C7b9 Eb7b9 Bbmaj7

These sound the same. The three pairs of changes before the last are just inversions with no forward movement... I will use "7dim" to refer to both 7dim and 7b9 below.

E7sus4b5 G7sus4b5 D7sus4b5 F7sus4b5 C7sus4b5 Eb7sus4b5 Bbmaj7

Now hear that the three pairs are no longer inversions, they press the movement.

If you play melodic lines that follow the 7sus4b5 harmonies, playing just 7dim or just 7sus4b5 lines through the three pairs does not really quite capture the feel to me. It has too much of a shifty-parallel sense to it (unless played really slowly like Miles' version)
However...

Harmonies
E7sus4b5 G7sus4b5 D7sus4b5 F7sus4b5 C7sus4b5 Eb7sus4b5 Bbmaj7

Melodies
E7sus4b5 G7dim D7sus4b5 F7sus4b5 C7sus4b5 Eb7dim Bbmaj7
or
E7sus4b5 G7sus4b5 D7sus4b5 F7dim C7sus4b5 Eb7sus4b5 Bbmaj7

As mentioned above, using 7sus4b5 for the three pairs makes the two harmonies in each pair different, not just inversions. Now, alternating the second of each pair between 7dim (or 7b9) and 7sus4b5 makes the adjacent pairs sound different from each other, not just shifted parallel progression segments.

Each actual song instance needs its own evaluation and judgement; in SBSL I prefer the sound and feel of expressing the 7dim once for the second harmony of the middle pair...

[buduranus2]

OP here. I'd like to thank everybody who contributed to this thread. If I were to try to summarize, it'd be that context determines whether the same chord is a rootless dom7b9 or dim7. Some of the comments were a little (a lot) over my head, such as a "cadential 6 4" etc, but it was fun to read them and try to parse them out as best I can. I think I also have a clearer understanding of how diminished chords "move." It may be a bit of an oversimplification, but they seem to be chromatic in nature, like a chordal passing tone. Anyhoo, many thanks and much appreciation for sharing your knowledge and perspectives.

[Christian Miller]

I think I also have a clearer understanding of how diminished chords "move." It may be a bit of an oversimplification, but they seem to be chromatic in nature, like a chordal passing tone.

yes (at least mostly)