Accidental

[luc]

Ok, I have a problem with a piece:
It's written in F major. And there's this chord with a C, a G and a B (with the C as the highest note) . and this B is sharped. How am I supposed to play this? Is the sharp meant as a natural accidental??

[xvimbi]

That sounds quite unusual - one would think the composer could have used a C instead. So, are you sure it's not a natural sign? They look awfully similar and depending on the edition/pdf/copy/hand writing one can easily confuse them.

A couple of hints to help you resolve this:
- how does the section sound with the different options? If it's a generally melodious piece, that should reveal the correct note, or at least narrow down the options.
- Is there another section that is identical or very similar (such as a sequence), which could give away the intent?

[luc]

It sounds very wierd when I play G,  B, C
 It's a Brahms waltz (op. 39 nr. 9). The chord is in the second bar (left hand).
Maybe it's a mistake, because when I play G, Bflat, C it sounds good
(It's also possible that I'm very very stupid now  )

[xvimbi]

It looks to me as if the # belongs to the C, not to the B. That wouldn't make sense anyway, because B# and C are enharmonic, and both are in that chord. Am I looking at the right spot?

[luc]

Yes, that's possible. Would sound at least acceptable 

[bernhard]

Yes, that's possible. Would sound at least acceptable 

xvimbi is correct. The chord is G - Bb - C#. The chord is A9 - or the dominant 9th (A is missing, E is supplied in the bass), so not only acceptable as orthodox I-V progression. (the piece is in D minor, so the first bar is a Dm chord - the tonic, followed by the dominant in the second bar).

Best wishes,
Bernhard.

[Floristan]

The C# appears first in the right hand, confirming that is the intent in the left hand as well.  Bernard's analysis is flawless, as always.