Posted by Ned on November 20, 2000 at 00:10:50:
In Reply to: Vented valves posted by Sun on November 13, 2000 at 00:52:33:
Vented valves equalize the pressure that builds up in a valve even if you don't adjust the slides. When you blow through a horn with a valve down and then let the valve up while still playing there will be air pressure trapped in the closed loop of the valve. This can cause bumps in legato playing. The vent just puts a hole in the closed loop, allowing the pressure to equalize when the valve is up.