[eftpotrm]

> To wit: when I play piano, I play in C. When I play guitar, I don't think about what key I'm in. I play in whatever fingering is easiest and what sounds best at the time.

I know what you mean, but I think that's significantly a keyboard-based hazard. I play the trumpet (mostly; I can do a very little on a few others and trying to improve) and I've frequently ended up jamming away in odd keys, switching between them as required. F# major is a relatively common key for me, I just hear the intervals and the fingers move quite automatically, even though trumpet harmonics are arranged around C major (well, concert Bb). I'm sure it's much the same on other wind instruments.

[hernan7]

Sax also favors the C major scale [].

Back in the early 20th century, sax salespeople would take advantage of this to sell the sax as an "easy to play" instrument. You can hang a saxophone from your neck and in 5 minutes you are playing the C major scale, Twinkle Twinkle Little Star, whatever.

Compare with the trumpet or the violin, where just playing your first major scale in tune scale in tune takes weeks of practice.

[] Actually, sax is a transposing instrument. But it does favor whatever scale you read as C major when you play it.

[eftpotrm]

OK, there's two separate things here :-)

Trumpet fingering is easiest in C, F or G majors (as read, concert Bb, Eb and F). The actual blowing is quite physical and needs a good bit of practice to build strength; that is easiest in C, and the lowest fifth of that too.

But.... There's only three keys, they always operate in the same sequence, so once you've learnt that fingerings flow quite easily, and the harmonics are good, useful intervals. Perfect fifth, perfect fourth, major third, minor third. That gives the five core open harmonics over a core range of two octaves once you use the valves. Hence, once you've got yourself going a bit, while some keys are easier than others the instrument's structure lends itself nicely to switching keys at will without major issues. It makes it a nice instrument for improvisation.