I am looking at a piece of music and there is a C# in the key signature. On the cello there is a C note on the G string and on the A string. I know that in a C# key signature the C on the A string is a C# but I want to know if the C on the G string is a C# as well.

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    If there's a C# in a key signature, that means when reading the music, whenever you see a C notated, play a C# instead, unless there's a natural sign in front of the C. It doesn't matter what string you are playing or even what instrument you are playing. Mar 27, 2016 at 20:10
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    @ToddWilcox - I could post an answer but there is really not much I could add to your comment. Why don't you just make it an answer before someone else copies and pastes your comment into an answer. Maybe in the answer version you throw in the term "accidental" to describe how a composer would notate a deviation from what is indicated in the key signature. Mar 27, 2016 at 21:18
  • I feel like this question is a duplicate actually, I just haven't taken the time to find the dupe. Mar 27, 2016 at 22:30

3 Answers 3


Yes, if the key signature included C#, it affects ALL C notes. No need to look for esoteric cases where a composer may have invented his own private system where something that LOOKS like a key signature has a non-standard meaning, though I'm sure some could be found. A key signature affects all octaves.

I guess there's an F# in the key signature too?

  • Yes. There is an F# in the key signature as well. The songs I play at my current level don't usually use the C string where the other F is where I would play the F# on that string
    – Katie
    Mar 28, 2016 at 3:48

The position of the sharps and flats on the key signatures is traditional and, generally, seems to have been "designed" to fit within the stave. If C# is indicated in the key signature then all C notes are sharp unless indicated otherwise during the piece.

On the cello you can play a C# on one or more strings - depending on the pitch. Which one you use will depend on the left-hand position and the preceding and following notes. There will be a difference in tone though and this will be more and more detectable with experience.


There must be an F# at the beginning followed by C# so we're on the key D. Whenever you see a C note, it means to play it in sharp unless you see a natural sign. And when you see such, it will only be effective for 1 bar.

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