Re: Re: Dent effects?


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Posted by Art H on December 07, 2001 at 23:52:30:

In Reply to: Re: Dent effects? posted by DF on December 07, 2001 at 07:41:27:

The trouble with an oval cross-section is that it will respond more to internal pressure changes. Increasing the pressure in a cylindrical pipe or in a horn with circular cross-section will only make the metal stretch a bit; the effect may be too small to notice. But increasing the pressure in a pipe or horn with oval cross-section will change the shape of the oval. That's why carbonated beverages never come in containers with oval cross-section. When you play a brass instrument the air pressure changes rapidly and periodically inside the horn. If the tubing is out of round then the air vibrations will cause metal vibrations, robbing sound energy from the air. Try blowing across a plastic coke bottle to make it sing like a flute. Then try again while squeezing the bottle to deform it from its normally round shape. Conn could get away with it with their short-action valves because they were just a short part of the instrument with very little flexibility. They actually offered a smoother air passage than most conventional pistons do.


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