Posted by Ian Robinson on August 27, 1999 at 22:31:37:
In Reply to: Porting/Venting posted by Alan on August 20, 1999 at 12:26:04:
I personally feel that valve venting should be illegal. In a perfect world new tubas would all have tight valves, sadly this is not the case. Almost every vented tuba that comes into the shop that I work in leaks like a siv; the more vents and / or the older the horn is the worse it gets. Rotor vents can be plgged up but pistons need to be rebuilt/refit to stop leakage. Also remember that rotary valves are only tight at the bearing surfaces (top & bottom)the sides are meant to be a little loose thus causing at least a slight leak from the start. Hope this info is of some help.
I.R.