Diminished 7th chords - naming conventions?

viz

Because it functions as a II chord, at least my ear is placing it there, doing II-chord stuff. Being a friend of the V.  Also the tune - it goes from the B of the b7 to the A#, which makes you go huh? Ah that sounds like the major 3rd of something. 

It can’t really be an A (b9) because it’s intentionally NOT the expected A. If the A were next, it would clearly be a passing chord to the A, it’s not an A itself. And the b5 and b9 only really work well in an altered context, which works on the dominant (or in this case, secondary dominant) - it just sounds wrong to have those flat notes, plus the jangly A#, and think of it as any type of IV chord. You really don’t wanna hear that on a IV chord;

and C just isn’t in the blues progression at all. I’m out at the mo and can’t really get my inner ear to sing it, so not sure why it doesn’t fit, will come back to it

HAL9000

viz said:

…and C just isn’t in the blues progression at all. I’m out at the mo and can’t really get my inner ear to sing it, so not sure why it doesn’t fit, will come back to it

Agreed, but it does share the E and G with an A7 and also with the E minor pentatonic which, to my ears anyway, is why it kind of works. I’ll admit it doesn’t resolve particularly well to the E unless it’s followed by something (such as A7 or B7) to help it along a bit. Using the dim 7th somehow manages to avoid this.

HAL9000

beed84 said:

Personally, I generally go with the simplest route and would see A#dim7 as a substitution of A7 dominant chord and also a “passing chord” into E7 

This is what I’m thinking - I’m seeing the dim7 chord as a substitution for either A7 or C7 as well as a passing chord. I don’t really hear the F#7 although I understand @viz ’s reasoning. I think it’s because the vocal line is focused around the G note so doesn’t sit well over an F#.

Littlejonny

HAL9000 said:

merlin said:

There are only three minor third intervals in a dim chord…

Indeed. My mistake.

merlin said:

E dim is made up of four completely different notes to A#°, namely, E, G, Bb and Db. It wouldn't work as E dim at all. 

What am I missing here then?

A#° - A#, C#, E, G
E° - E, G, A# (Bb), C# (Db)

…aren’t these two names for the same thing?

I believe you’ve spelt the A#dim chord correctly, but the Edim chord would be E G Bb Db. That way you’re spelling the intervals correctly. Most chords stack in thirds so you spell them that way…it’s the same with e harmonics in melodic lines, the line should represent the melodic contour as much as possible, which informs your choices of enharmonics.

beed84

HAL9000 said:

beed84 said:

Personally, I generally go with the simplest route and would see A#dim7 as a substitution of A7 dominant chord and also a “passing chord” into E7 

This is what I’m thinking - I’m seeing the dim7 chord as a substitution for either A7 or C7 as well as a passing chord. I don’t really hear the F#7 although I understand @viz ’s reasoning. I think it’s because the vocal line is focused around the G note so doesn’t sit well over an F#.

Correct me if I'm wrong, but I think @viz is approaching it in a more "harmonising the major scale" way rather than a substitution/passing chord way. For example, F#7b9 is another way of saying Gº – on the one hand you've got the dominant II in E major, on the other you've got most of the notes only a semitone away from B7.

Brad

@HAL9000 sometimes with music, the most obvious answer is the right one

We’d usually find that diminished chord in bar 6, acting as a #IV°7/bV°7 and as @viz says, we don’t usually place alterations on the IV so it’s probably not really helpful to think of it as being A7b9 (or any of the other options IMO) because it isn’t a substitute for A7b9 in this case (even though it is, generally speaking), it’s an A#°7 (or Bb°7) in its own right. 

Where you’ve placed it in bar 10 is interesting and provokes quite the surprise due to the root movement. My ear is expecting to go to IV after V. Or to stay on V and maybe hit a quick I VI II V turnaround on bars 11 and 12, rather than going  bV°7 to I Iike yours does. Even though that exact change happens in bars 6-7 it sounds smoother ascending from IV. With your diminished chord in bar 10, I’m still hearing the 3rd and 7th pull to the 7th and 3rd of E7 (like bars 6 and 7), exactly what happens from A7 to E7 anyway and what my ear expects, but the A#/Bb serves up a dose of extra dissonance and without wanting to speak on his behalf, I’m assuming viz is hearing that note as part of a 1st inv F#(7) that wants to resolve to B then to E. Perhaps something akin to this:

x       x      x
5      4      5
6      4      4
5      4      2
x      x      x
6      5      4

That being said, much can be achieved with voice leading and selective chord voicings so it can be made to work as A7b9 and certainly F#7b9. Try the following voicings but over the second chord try all the possible options in the bass and see how they feel. 

 2       3      4
 0       2      3
 2       3      4
 1       2      2
(2)    (?)     x
 x      (?)   (0)

It’s your tune and I’m not going to tell you what you should hear or do with it. It’s tricky to advise without having a broader idea of what is going in musically. Personally, if A# is in the bass like has been shared, I don’t hear that as an inverted V/V in this context unless I phrase it in a certain way (I totally get the reasoning and it does sound great, particularly when part of a I VI II V) as the pull of the 3rd and 7ths overall is too much for me. 

However I guess all of these options are veering quite away from what your initial question is Diminished chords can simply be diminished and the root note determines what we call it. If you want A# at the bottom, A#°7 to E7. E at the bottom, E°7 to E7. If you were to play a voicing with Bb as the lowest note but the bassist plays G, you’d have G°7 to E7. You wouldn’t really call A#°7 an E°7, even though they’re the same notes and we are told we can name them as such. It’s a little misleading IMO.