You have to love an old trumpet and a beat up case. Great take on the challenge. I like the way you used the light. Additionally it is difficult to balance light without blowing the highlights completely out on a shiny subject like a trumpet, and I think you did a great job keeping that pretty well balanced. My one area of critique is the crop. Cutting off the bottom left of the case pretty clearly takes away from the image. Still a great shot :)
I like the concept a lot (and I have a very similar looking trumpet sitting in a very similar looking case in my own basement!). Compositionally, I think this would have been better had the lower corner of the case not been cut off. It feels like there's too much space at the top of the shot.