Posted by Henry on October 21, 2003 at 15:20:51:
In Reply to: vented vs leaky posted by Mary Ann on October 21, 2003 at 14:55:26:
"Leaky" vents from the active tubing into the atmosphere and everything else in the vicinity because of clearance twixt the piston or rotor and its associated casing...... "Vented" allows the positive or negative pressure in the non-active tubing to be released to the atmosphere but retains a positive seal on the active tubing through a carefully placed hole. By "active tubing" I intend the tubing currently directly in the path of the air/vibration flow from mouthpiece to bell. "Non-active" would be the first valve slide tubing when the first valve isn't depressed.
A bad enough leak would cause problems with playing as, in effect, new vents are added to the resonating tube which comprises the tuba at the point of the leakage. A vent has no effect on playing since it is not in the active system; it just eliminates pops, ETC when you manipulate the slides with the valves closed.
Did you ever foam the case?