Posted by Art H on August 25, 2003 at 23:20:45:
In Reply to: Re: Re: Tuba metallurgics, carbon sousas posted by Alex C on August 25, 2003 at 20:08:36:
You don't want square tubing for two reasons: First, the flat sides will go into sympathetic vibration, robbing sound energy from the air column. A plastic soda bottle provides an excellent illustration: Blow across it as you would blow a flute, to get a tone. Then squeeze the bottle out of round and try blowing it again. You can't get a note out of it because the flat regions on the sides of the bottle absorb sound energy just as a drum head does. (That's why snare drums rattle when you play a tuba in the same room; flat flexible surfaces absorb sound energy very efficiently.) The other reason why you don't want square tubing is the fact that it will have more surface area for the moving air to "rub" against, resulting in more sound energy being transformed into heat.
To maximize the sound coming out of a tuba you need to minimize the amount of sound energy that gets wasted inside the instrument.