Diminished 7th chords - naming conventions?

So a chord consisting of four minor third intervals - eg B D F Ab - I guess naming convention here is all about context? 

There are only three minor third intervals in a dim chord, then it just repeats itself up a register. It's best to name it  whatever the root note is, followed by the dinky little circle °. 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. 

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?

It depend on the bass note of the chord. In your example one is E and the other is A. In a band it will depend on what the bass guitar is playing

Roland said:

It depend on the bass note of the chord. In your example one is E and the other is A. In a band it will depend on what the bass guitar is playing

Yes, I tend to think about what the bass line is doing when I come to name a diminished 7th chord.

A Diminished triad is comprised of two minor 3rds above the root - 1 b3 b5

A Diminished 7th is comprised of three minor 3rds above the root - 1 b3 b5 bb7

Taking A# as the root: 

A#º - A#(1), C#(b3), E(b5)
A#º7 - A#(1), C#(b3), E(b5), G(bb7)

As they are symmetrical, any one of the notes can act as the name of the chord as they are "all the same" so to speak.
A#º7 is the same as Gº7 for example (and Eº7 and C#º7) 

If I'm understanding you correctly, you're really thinking in terms of a dim7th rather than a diminished triad. But in either case it would imply an A7b9 sound (more so A#º7 as it has the b7(G) of A7 which is not present in the A#º triad).

For me in depends on the context, where the chord is placed in the progression etc. I wouldn't call it Eº unless E was in the bass of the chord... even then I'd still really think of it as A7b9 so maybe A7b9/E. If A# (or Bb) is in the bass I'd be more inclined to use it's diminished namesake.

  

That A#dim7 (assuming you’re actually playing or thinking all 4 m3 intervals), can actually be thought of as an …. 




…..



F# chord


People will disagree with me (and their answers are just as right as mine) because a) it doesn’t even contain F#!! and b) because what the hell has F# got to do with anything?

But it’s basically functioning as a secondary dominant II chord, which would go to the B, and then the E. Ok it misses out the B (because the B has already happened), but you can see what it’s doing. It’s like a ii-V-I. But it’s a secondary dominant so it’s a II7 (a dominant chord) - V (absent!) - I.

But wtf are we calling it F# for, lol?

viz said:

That A#dim7 (assuming you’re actually playing or thinking all 4 m3 intervals), can actually be thought of as an …. 




…..



F# chord


People will disagree with me (and their answers are just as right as mine) because a) it doesn’t even contain F#!! and b) because what the hell has F# got to do with anything?

But it’s basically functioning as a secondary dominant II chord, which would go to the B, and then the E. Ok it misses out the B (because the B has already happened), but you can see what it’s doing. It’s like a ii-V-I. But it’s a secondary dominant so it’s a II7 (a dominant chord) - V (absent!) - I.

But wtf are we calling it F# for, lol?

Because it has 

F# (well ok that’s missing)
A# (the 3rd) 
C# (the 5th)
E (the flat 7)

and then it has a G, which is the b9. So it’s F#7b9 (no F#)


Anyway that’s what it’s doing, functionally speaking. 

Bang on.

Oh don’t worry, I always bang on, and on!

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?

Sorry, I was being smart assed and talking enharmonics. Sorry, yes they're the same thing but you need the root (bass) note to define which chord it is. 

@viz nice way of looking at it, particularly when it’s the II of a I VII II V. 

Brad said:

@viz nice way of looking at it, particularly when it’s the II of a I VII II V. 

I’d handle with care though, I’d argue it runs the risk of sounding a bit random if voiced incorrectly in the context given, particularly as it doesn’t go up a 4th (IMO of course). It’s a 3rds and 7ths/voice leading issue for me

Absolutely - it's a II7 - I, not a II7 - V7 - I.

The II is in 1st inv obvs, didn't mention that before.

But yes, handle everything I say with care!

One thing I've noticed is that in charts written by pros with much better education in music theory than I do (I have zero formal musical education so not hard) the naming of diminished chords is often pretty random. In particular I see charts for songs where the same chord patterns are repeated with changes of key and the name given to diminished chords isn't consistent.  I'm not suggesting this is okay, just that it seems to be common for arrangers to think that as long as the chord symbol is telling you to play the right notes they don't need to be too fussy about what to call it.

@viz said:

That A#dim7 (assuming you’re actually playing or thinking all 4 m3 intervals), can actually be thought of as an …. 




…..



F# chord


People will disagree with me (and their answers are just as right as mine) because a) it doesn’t even contain F#!! and b) because what the hell has F# got to do with anything?

But it’s basically functioning as a secondary dominant II chord, which would go to the B, and then the E. Ok it misses out the B (because the B has already happened), but you can see what it’s doing. It’s like a ii-V-I. But it’s a secondary dominant so it’s a II7 (a dominant chord) - V (absent!) - I.

But wtf are we calling it F# for, lol?

Because it has 

F# (well ok that’s missing)
A# (the 3rd) 
C# (the 5th)
E (the flat 7)

and then it has a G, which is the b9. So it’s F#7b9 (no F#)


Anyway that’s what it’s doing, functionally speaking. 

I don’t disagree as what you say is theoretically correct and another way of looking at things. Especially if you want the chord to function in a certain way like you described. Of course, it opens up other possibilities, too.

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 

viz said:

Brad said:

@viz nice way of looking at it, particularly when it’s the II of a I VII II V. 

I’d handle with care though, I’d argue it runs the risk of sounding a bit random if voiced incorrectly in the context given, particularly as it doesn’t go up a 4th (IMO of course). It’s a 3rds and 7ths/voice leading issue for me

Absolutely - it's a II7 - I, not a II7 - V7 - I.

The II is in 1st inv obvs, didn't mention that before.

But yes, handle everything I say with care!

Which opens up a host of possibilities for substitutions if we're thinking rootless chords... C7b9 and Eb7b9 to go with A7b9 and F#7b9 as already discussed. Handled with the utmost care of course :wink:

viz said:

That A#dim7 (assuming you’re actually playing or thinking all 4 m3 intervals). 

Yes, definitely thinking dim7 (4 m3 intervals)

viz said:

F# chord

Interesting. I’m out right now but will definitely experiment with an F# later. The sound in my head though definitely needs the dissonance of a dim7 or perhaps a C7 (which still has the E, G, and Bb (A#) from the dim7. I guess the dim7 kind of acts a bit like a C7 and an F# and an A7 so can act as a substitution for any of them.

Blueingreen said:

One thing I've noticed is that in charts written by pros with much better education in music theory than I do (I have zero formal musical education so not hard) the naming of diminished chords is often pretty random. In particular I see charts for songs where the same chord patterns are repeated with changes of key and the name given to diminished chords isn't consistent.  I'm not suggesting this is okay, just that it seems to be common for arrangers to think that as long as the chord symbol is telling you to play the right notes they don't need to be too fussy about what to call it.

I think it's down to the duality of them, but also the context is the big thing. Take the first 4 chords of How Insensitive by Jobim which more often than not is written Dm9 - C#º7 - Cm6 - G7/B. It is completely legitimate to think/use A7b9 instead of C#º7 (as they are seen as interchangeable), but then the melody wouldn't work as well and the descending root movement would be lost. For the G7/B, Bº would be perfectly fine (again, interchangeable) but going G7 wouldn't describe the harmonic relationship in quite the same way, the melody would lose it's place and again, whilst it wouldn't sound bad, we'd lose more descending root movement.

Taking those four chords, and keeping in mind the possibilities of naming diminished chords... 

Dm9 - Eº7 - Cm6 - Dº
Dm9 - Gº7 - Cm6 - Fº
Dm9 - Bbº7 - Cm6 - Bº

None of those diminished triads or 7ths are wrong as such (as they're all inversions of each other so fair game) but they're not completely descriptive of what is actually supposed to happen musically. I'd have a headache if I saw any of those on a gig for this song  But I know I can use them as voicings in my comping if the bass player is playing C# and B respectively, or if said bass player decides to invert any of them then that's on them  

But how that relates to charts one writes can be many different things. Even the best musicians can chart things out that only really mean something to them. I'd have look at the kind of charts you're referring to, but often there can be a method to the (perceived) madness.  

Yeah but can you play a Am eh?

Brad said:

Taking those four chords, and keeping in mind the possibilities of naming diminished chords... 

Dm9 - Eº7 - Cm6 - Dº
Dm9 - Gº7 - Cm6 - Fº
Dm9 - Bbº7 - Cm6 - Bº

None of those diminished triads or 7ths are wrong as such (as they're all inversions of each other so fair game) but they're not completely descriptive of what is actually supposed to happen musically. I'd have a headache if I saw any of those on a gig for this song  But I know I can use them as voicings in my comping if the bass player is playing C# and B respectively, or if said bass player decides to invert any of them then that's on them  

That’s it. IMHO it’s best to go with what fits the context and whichever convention is the easiest to understand.

beed84 said:

That’s it. IMHO it’s best to go with what fits the context and whichever convention is the easiest to understand.

Bingo. Theory describes what’s played, and there can be many descriptions depending on your point of view. 

viz said:

That A#dim7 (assuming you’re actually playing or thinking all 4 m3 intervals), can actually be thought of as an …. 




…..



F# chord


People will disagree with me (and their answers are just as right as mine) because a) it doesn’t even contain F#!! and b) because what the hell has F# got to do with anything?

But it’s basically functioning as a secondary dominant II chord, which would go to the B, and then the E. Ok it misses out the B (because the B has already happened), but you can see what it’s doing. It’s like a ii-V-I. But it’s a secondary dominant so it’s a II7 (a dominant chord) - V (absent!) - I.

But wtf are we calling it F# for, lol?

Because it has 

F# (well ok that’s missing)
A# (the 3rd) 
C# (the 5th)
E (the flat 7)

and then it has a G, which is the b9. So it’s F#7b9 (no F#)


Anyway that’s what it’s doing, functionally speaking. 

So why do you see it as an F#7 rather than, say, an A7 or a C7?

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. 

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.

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#.

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.

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.

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