Re: m7.5- transposed to sus#4 b3 ??

[Malte Meyn]

Am 11.11.19 um 21:38 schrieb Sandro Santilli:
> I transcribed an A major song with this chords snippet:
>
>    ees:m7.5- | aes:7 | aes:m7.5- | des:7 |

Are you sure you want those chords instead of

dis:m7.5- gis:7 gis:m7.5- cis:7

? Who wants to read a a-flat half-diminished chord (a-flat c-flat 
e-doubleflat g-flat)?


> When transposing it to Eb major it is rendered as:
>
>    Bbbø | Ebb7 | Ebb7sus#4 b3 | Abb7
>
> I don't understand why the third chord (m7.5-)
> gets rendered as a "7sus#4 b3" chord, very hard
> to read ...

The bigger problem is that while a-flat half-diminished is at least hard 
to read, e-doubleflat half-diminished is just insane.

LilyPond 2.18.2 did the most sane thing it could do and changed the 
b-tripleflat to a a-flat in that chord. You can see this if you output 
not only as ChordNames but also as regular notes:

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\version "2.18.2"

C = \chordmode {
  ees:m7.5-  aes:7 aes:m7.5- des:7
}

<<
\new Staff \C
\new ChordNames \C
\new Staff \transpose a es \C
\new ChordNames \transpose a es \C
>>
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

> Ideally I'd also like to avoid the double flats,

You definitely should do that. Ideally by not using the single flat 
chords in the a major version in the first place … But if you really 
want to keep them, try transposing to d-sharp instead of e-flat.

> but what strikes me is the "sus#4 b3" part, is it
> a bug ? I'm using GNU LilyPond 2.18.2 and the
> .ly file has a \version "2.18.2" header.

LilyPond 2.19.83 can handle triple flats (but cannot show them as notes 
because it doesn’t really know how a triple flat accidental should look 
like) so the output of the snippet above is “correct” with that version.