Key signatures in classical works

[bob_32_116]

It was probably the case that certain keys sounded noticeably different from other keys before the introduction of "equal temperament", and this is probably the reason you hear statements like F minor being the saddest key. With equal temperament, though, when one key is transposed into another the frequency ratios of the notes stay precisely the same, hence I am very sceptical of claims that. for example, a piece played in C major acquires a slightly different mood when transposed into C# major. Any difference in sound would be due to the properties of the particular instrument, i.e. the response, frequency harmonics etc might be slightly different for certain notes than others, rather than inherent properties of the notes themselves.