I mostly agree with all the above, but as a guitarist/singer* there is distinctly something about transposing songs - it is clearly obvious that most songs work best in their original keys and quite a number of times transposition completely changes how a song sounds, to the point where some songs when transposed simply do not work at all.
If music was all about relative intervals, surely this wouldn't be an issue?
* Not the world's best singer, hence my observations around transposition, as I try to bend songs I like into a range I can just about manage.
That's because you are using a guitar, which is not perfectly in tune no matter how you tune it.
For an equal temperament instrument (like a midi keyboard), transcription would be seamless.
For a fretless instrument, transcription can be made seamless, if the player is good at intonation.
However, the timbre of the instrument can still be a little different for each key (e.g. open strings vs fingered notes), but that's a nuance on instrument rather than transcription per se.
At least on violin the different strings have slightly different timbres, as do different fingerings. Playing a G4 as 3rd finger on the D string will not sound the same as playing it in third position on the G string even with very precise intonation.
Sound recording, reproduction, and even instrument resonance are usually not a perfectly flat EQ also, so transposing up or down can hit different frequency-dependent distortions.
That’s not quite correct. To perfectly preserve, you’d also need to change the string thickness, tension and weight, which may involve a change of materials, and may not even be possible to retain proportionality between strings. You’d have to change the body of the guitar as well.
I have no idea which is further from a purely pitch adjusted version of the original! The key (no pun intended) takeaway is that virtually all instruments sound different in each key, and just playing higher will sound different to eg recording and adjusting the pitch digitally (or analog-ly).
Oh, you are about timbre. Sure capo can't change that.
> That's because you are using a guitar, which is not perfectly in tune no matter how you tune it.
I've though powersnail point is about different shapes and your comment is about True Temperament guitar [1], [2].
Do you think timbre is the reason we notice pitch changes? And we would not notice transposition if it was pure sine? I am sure going to test it [3] and will add pure sine instrument.
If music was all about relative intervals, surely this wouldn't be an issue?
* Not the world's best singer, hence my observations around transposition, as I try to bend songs I like into a range I can just about manage.