TubeNet

http://www.gassermusic.ch/okkdetail.asp?OkkasionID=107

Compensating 3 valve Hirschbrunner rotor? I have a little dispute with a seller of such an instrument. He claims it to compensating and refers to this url. I can't see if it's compensating, do you?

Yes, it is a compensating instrument. The rotors are double-decked. Look at the one tubing loop coming out of the third valve, but looping back around the block instead of looping into the bugle. Here's two more threads, one with pictures, on the subject:

viewtopic.php?t=15662
viewtopic.php?t=15436