Re: Vented pistons


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Posted by Alex C on July 11, 2003 at 10:30:22:

In Reply to: Vented pistons posted by Pat on July 11, 2003 at 09:14:45:

I have vented both rotary and piston valve, but I did not find that it helped me or my students (regardless of their playing ability) to slur more easily.

It did allow slides to be pulled to correct intonation issues without causing a pop when the valve was depressed.

The principal problem with rotary valves is that as the valve is depressed, you are momentarily half valving which causes the air to swirl around the valve and in the tubing. This has been demonstrated in visual studies using clear plastic tubing and valves with smoke filled passageways.

I can see that this could cause some change in air pressure but I don't know what it would be, negative or positive pressure. I've seen no studies. More importantly, and also unknown, is what happens to the vibrating air column when this happens.

This problem is virtually eliminated with piston valves. (I said virtually.)

But most importantly, many fine tubists seem to be able to slur with non-vented valves. Attack the problem from that direction.


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