A number of horn makers used hollow rotors back in the early 20th century. I see that Max Enders was in Mainz and I was going to mention that another Mainz maker with hollow rotors was Alexander (back in the good old days). A good chance they used the same supplier for valves? The change rotor on Kruspes was hollow but the other 3 were solid. More recently Paxman offered hollow rotors and some Yamahas have them. Hollow rotors usually have some kind of little vent hole so the pressure can relieve as the ports are being brazed in place. You have to be careful not to get water or even less desireable liquids inside there, they'll do inconvenient things later on!
- Steve Mumford _______________________________________________ post: horn@music.memphis.edu unsubscribe or set options at http://music2.memphis.edu/mailman/options/horn/archive%40jab.org
