You are not talking about valves, right? The cones trip the air flow in one direction and not in the other? I never thought of that. Sweet. Low pressure, though?

For valves I was thinking flappers. They have to be carefully made or they will break unpredictably. Metal is best for heavy use, and this gadget is heavy use. Beryllium copper, about 0.010 thick.

Thanks for the talk, very enjoyed.

Have spent a lot of time looking at the LAB horn, very interesting, the more you look the more you see.

Really enjoying your crossover paper. Makes me feel smarter than I really am!