The diminished chord

[wirralaccordion]

On a piano accordion with a sixth row of bass buttons, the bottom row of bass buttons being the diminished chords, does this button play all 4 notes of the chord or does it play only three notes and if so which three?
e.g. For the C column does the button play C, E flat, F sharp and A? If not which three notes does it play and is this the same three within the chord for all the diminished chord buttons on the sixth row?

 

[Glug]

According to https://accordionchords.com/stradella-bass-layouts/96-bass-accordion-chart/
it plays C + E flat + A

 

[losthobos]

Standard stradella diminished is C,Eb and A.....(so a rootless F7 or Amin7b5)....so for all chords is R,b3,bb7
French 3x3 stradella no diminished but button below ...ie F7 next to C also doubles as C dim by being the notes A,C,Eb....

 

[micahcowan]

Yeah, it irks me a tiny bit, because the reality is that the standard voicing for the so-called "C dim6" is, in reality, an "Adim" (no 6). When I want a proper dim6, I add the one 3 rows down from it (Cdim6 + E♭dim6 = true Cdim6). You can also play 3 rows the other direction.

However, what I do love about the diminished-chord voicings, coupled with the (missing 5) dominant 7th voicing, is that if you trill the 7th and dim of the same chord-line (ideally with index and middle, but index and thumb can work), then the tonic note (C, if on that row) stays stationary, while a tritone shifts a half-step back and forth around it.

The C7 is often described as "C E (no G) B♭", but I tend to think of it as "B♭ C E", and the dim6 as "A C E♭", so yeah - makes for a very nice kind of "funked" slide into the C7!

 

[Rosie C]

According to https://accordionchords.com/stradella-bass-layouts/96-bass-accordion-chart/
it plays C + E flat + A

So it's called Cdim, but it's actually "Cdim7 (no 5)". But Cdim7 with a missing 5 is Adim!

Oh, this makes my head hurt!

 

[losthobos]

Adim, Eb dim, F#dim, C dim.......
All inversions of same chord.....

 

[Rosie C]

Adim, Eb dim, F#dim, C dim.......
All inversions of same chord.....

Indeed, it's not the music theory but the naming. I have an urge to strip down the bass machine and swap all the "dim" pistons around so that they play what I expect them to play - e.g. the C dim button plays a C dim (no 7) chord!

 

[micahcowan]

Adim, Eb dim, F#dim, C dim.......
All inversions of same chord.....

I mean... that's true of fully-diminished 7ths, but not of a standard diminished triad. And it's usually not noted as a diminished 7th, but as a "C dim" or whatever. It's "just true enough" for them to get away with calling it a "C diminished 7", but without the flat fifth it really isn't one. I mean, if you show me those notes on paper or on piano, I'm going to say "A diminished". If you show it to me with the C at the bottom, I'll say "A diminished, 1st inversion". Without the G-flat, I'm not really calling it a "7th" of anything", because without the 5th your "7th" is the root. And yeah, it is the same thing as a C fully-diminished 7 that's just missing the 5th, but I feel like calling it a "C diminished 7", and particularly, abbreviating it most of the time as "C dim" is a bit of a white lie.

I mean, anyone with an understanding of music theory will understand that if you play an A dim atop an F, what you have is a dominant F7. But if you play an "A dim" over an F on the accordion, what you'll get is an ugly, ugly sound (I mean, idk, maybe you wanted a flat 9 in the mix? But given that the 9th will just as likely be played as a minor 2nd...). To get the a F7 on an accordion (ignoring the F7 button), the "correct" diminished chord to play would be "C dim", not "A dim", and this is why the naming is a bit disingenuous IMO. (In reality of course, if I want a full F7 I'm more likely to play FM and F7 simultaneously, so I've both the 5th and the 7th).

I mean, it's just a name, and I'm content (despite the rant here) to call it a "C dim" because that's what everyone else will do, and it'd be confusing (in an accordion context) to call it something else. But when I'm in "composer" mode, or thinking in terms of raw music theory, well then it's an A dim, because that's what the notes spell!

 

[dak]

I mean, it's just a name, and I'm content (despite the rant here) to call it a "C dim" because that's what everyone else will do, and it'd be confusing (in an accordion context) to call it something else. But when I'm in "composer" mode, or thinking in terms of raw music theory, well then it's an A dim, because that's what the notes spell!

To me they spell Cm6 without fifth. You can use the Cm button to add it.

 

[JeffJetton]

It is unfortunate that we usually call that row the "diminished" row, because it is indeed really designed to play a diminished 7th chord and *not* a diminished triad (which is what most people think of when they hear/read "dim" without the "7"). I make a point in lessons to refer to it often by its full name.

"Ah, but it's missing the fifth! Or flat fifth, in this case!" you may say. Well sure, but that's no big deal. Actually preferable, if you ask me.

• We also leave the fifth out of the 7th chord buttons too, so it keeps voicings consistent. (It's the least important note in that chord anyway, and you can always add it by playing the major button too.)
• It lets the button double as the arguably more-useful minor 6th chord. (Yes, it omits the fifth, but like the 7th chord, it's the least important note and can be added with another button if you really want it.)
• I feel like dim7 chords are more common than plain ol' dim triads, although I suppose that depends on the sorts of music you play.
• A final important reason that's a bit complicated: While harmonic movement among/across major/minor/7th chords is commonly up and down in 5ths, and thus very convenient on Stradella, diminished 7th chords tend to be used in chromatic harmonic movement. As "passing" diminished chords, such as a CM, C#dim7, Dm progression.
  • Chromatic jumps on Stradella are not optimal, so it's a bit of pain to play the C#dim7 in my example on the real C# row (assuming you even have one)
  • Playing in enharmonically as Db dim7 isn't much easier.
  • But... you can combine C# bass (counterbass of A) with the surprisingly-close Gdim7 button. Since dim7 chords invert into other dim7ths chords, this winds up being the same as C#dim7. (There are really only three dim7 chords if you consider inversions to be equivalent.)
  • Since the Gdim7 button leaves out that flat fifth, and since its flat fifth happens to be C#, and since you get that C# back due to it being the root of the chord you're playing as a bass note, this way of playing a C#dim7 is not only easier to execute, it's actually a full, four-note, 100% correct diminished 7th chord! It's better all around!

 

[wirralaccordion]

According to https://accordionchords.com/stradella-bass-layouts/96-bass-accordion-chart/
it plays C + E flat + A

So on a 80 bass accordion where the fifth row is used to cover both a dominant 7th chord AND a diminished chord you would expect the three notes to be E, G and B flat as these three notes are common to the dominant 7th of C and but the diminished chord of any of C sharp, E, G or B flat.
But it doesn't?

 

[dak]

So on a 80 bass accordion where the fifth row is used to cover both a dominant 7th chord AND a diminished chord you would expect the three notes to be E, G and B flat as these three notes are common to the dominant 7th of C and but the diminished chord of any of C sharp, E, G or B flat.
But it doesn't?

Who says it doesn't?

 

[micahcowan]

So on a 80 bass accordion where the fifth row is used to cover both a dominant 7th chord AND a diminished chord you would expect the three notes to be E, G and B flat as these three notes are common to the dominant 7th of C and but the diminished chord of any of C sharp, E, G or B flat.
But it doesn't?

You spoke specifically of the standard Stradella sixth row, and that's what we've been discussing to now. @losthobos already addressed "double-duty" fifth rows, and it's as you describe here:

French 3x3 stradella no diminished but button below ...ie F7 next to C also doubles as C dim by being the notes A,C,Eb....

 

[wirralaccordion]

Who says it doesn't?

Well on my accordion it plays E, G and B flat. So it can be used as the dominant 7th of C ( C missing ) or the diminished of C sharp, E, G, or B flat ( C sharp missing ). According to the next post the diminished chord of C is going to be the fifth button in the F column.