I'm a trumpet player. I picked up an Eb alto/tenor horn really cheap, and have been playing around with it. Someone told me I could play trombone music on it if I read it as though it were treble clef, go up three 5ths on the key signature, and read it an octave lower than written.
Being in a hurry, I did not bother to print the trumpet parts from the brass quartet arrangements I downloaded, but instead, I tried to play the trombone part from these arrangements along with a trumpet playing the trumpet part from a duet arrangement of the same Christmas collection.
I spent an hour trying to figure out what I was doing wrong, with a Centerpitch CP-2 tuner on my horn making sure I was playing the right notes, and my ear kept telling me there was something grossly wrong with this situation. I thought maybe the guy who suggested how I could read trombone music was off in his formula somehow.
Then I did some mental math and figured out that a trombone part in F does not equal a trumpet part in Bb.
The duet arrangement parts are all in different keys from the quartet arrangements.
I'll have to try this again now that I've printed the trumpet parts from the quartet arrangement. Since I don't see any trombone/trumpet duets
available off hand. Not within the Christmas domain anyway, and probably not within the spectrum of music I can actually play anyway. Most of the stuff I've downloaded from here I've printed just to aspire to one of these decades.
There's no harm in dreaming and aspiring though. One of these days I'll play Moto Perpetuo
. It might take me 50 years to get that good though, at this rate.