Re: error in predefined chord diagram?

[David Kastrup]

Carl Sorensen <address@hidden> writes:

> The source for the chord is this:
>
> http://www.8notes.com/guitar_chord_chart/Cxdim.asp
>
> But my "The Gig Bag Book of Picture Chords for all Guitarists" lists
> that same chord as C#dim7, but also says that dim and dim7 are
> alternate names for the same chord.
>
> According to Wikpedia, "In most sheet music books, Cdim or C0 denotes
> a diminished seventh chord with root C. and Cm-5 or Cmb5 denotes a
> diminished triad with root C.  However, in some modern jazz books and
> some music theory literature, Cdim or C0 denotes a diminished tirad,
> while Cdim7 or C07 denotes a diminished seventh chord."
>
> So at least from these references, there is a difference of opinion
> about this notation.
>
> If we can get agreement from the guitarists on the list about what is
> right, we'll fix it to what is agreed.

I think we should include accordionists in this discussion...
Accordions build their chords from notes of a fixed octave (never mind
inversions, there are separate bass buttons establishing the bass tone,
usually by alternating with the chord button).  It has "seventh" and
"diminuished" chords that are notable for not including a fifth.  So
indeed C#dim would be C# E Bb on an accordion.

Accordion chords have a number of different styles of notation.  One is
just spelling out the actual pitches.  And that's basically what we want
to be doing in the case of guitar chord diagrams/tabulature as well.
There is no point in spelling out a keyboard chord in tabulature or
specific guitar notes.

But there is a point in writing _keyboard_ chords in notes but putting
chord diagrams for guitar above.

So basically we need a mechanism that can take a bunch of keyboard
chords and route them through predefined chord set translator for a
particular instrument, be that an accordion (which does not bother all
too much with fret diagrams actually, so this translation should not be
tied to them all too much) or a guitar.

-- 
David Kastrup