I asked this on my newbie intro post but thought I would ask again here to allow it a wider audience. My question is this: If a mate says let's play "When the Saints" in key of C then I'm with it straight away. I'm thinking C and I'll know where to put my fingers for the scale (not necessarily on the trumpet yet, but you know what I mean) and I know the other chords we'll be using and away we go. But what goes through the head of you transposing music readers when you're playing by ear though? Do you think middle C that's 1 & 3 like me? Or do you tell yourself you're playing in D so you play in C? I dunno! Can't imagine really! Tedh1951 kindly took the time to reply and said: Mate, I have NO idea - I'm a community player with a bunch of pretty trumpets - I play to support my kids and have fun (I participate on TM for the same reason, to have fun). Ask for middle C and I play open - ask for Bb and I purse my lips and play 1st valve - simple really. You will need a MUCH smarter player than me to address this question. To which I replied: Thanks, Ted. This is why I can't get my head round it. In your case, when asked for a C you're actually playing Bb. OK if you're all playing off the same hymn sheet, so to speak, but I'm wondering about when you're just jamming. For some reason I'm unable to edit this once I've typed it so I hope it's clear! Anyway, what's the answer, please????