Here the orchestra plays in D but the french horn is written in C major when it should be written in A major. There are accidentals but I dont understan why the correct key signature is not used?enter image description here

  • Note that the trumpets also appear to not be written in E, as they theoretically would be since they are transposing instruments. As PiedPiper answered, horns and trumpets often don't get key signatures. Also note that the Clarinet is in A, not the more common Bb. Feb 26, 2023 at 20:48
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    What is it about this score that leads you to believe that the horn is not written a fifth above sounding pitch? What transposition do you think is in use? Why?
    – phoog
    Feb 26, 2023 at 21:59

2 Answers 2


Traditionally horns have always been written with no key signature.
When horns were introduced into the orchestra they had no valves, and had a very limited set of notes. To change key extra tubing, known as 'crooks' were added. Since the horns were mostly in the key of the piece, no key signature was needed.
Nowadays horns have valves and can play chromatically, but the tradition of leaving out the key signature has continued. Modern hornists should be able to read key signatures, but there are still plenty who pencil-in every accidental.

In the example from the question, the horns are transposed for horn in F. In the first half of the first measure they are playing a written A-major chord, which will sound D major.

Also relevant, but probably not quite a duplicate: Horn & Trumpet and Key Signatures

  • So not only are they written a 5th above the actual pitch but they are written without a key signature... hmm, This seems silly to still not use a key signature in present day though
    – user35708
    Feb 28, 2023 at 19:36
  • @armani It's an anachronism, but horn players seem to prefer it that way.
    – PiedPiper
    Feb 28, 2023 at 22:20

Also, you'd expect the trumpets to be in 4 sharps. But there's a convention that orchestral horns and trumpets are written transposed, but in open key with accidentals. The reason for this is historical and, to be honest, now rather dubious. But it's still done.

Not to be confused with a modern convention of concert pitch scores, where EVERY instrument is written at sounding pitch. De rigueur, for some reason, in movie scores.

And watch out for modern scores where a lack of consistent tonality makes it appropriate to write in open key, but transposing instruments ARE transposed.

It can get confusing!