Re: Re: Re: vented vs leaky


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Posted by js on October 22, 2003 at 12:23:52:

In Reply to: Re: Re: vented vs leaky posted by Mary Ann on October 22, 2003 at 10:39:14:


As far as I'm concerned, YES.

With large bore tubas (assuming tightly-machined valves), that cute little "pop" can become a "SLAM" against one's embouchure when trying to slur (after just adjusting a slide for the next pitch) or a horrible "POW!" coming out the bell which is as audible (or sometimes even more audible) to the audience as the sounds intended to come out the bell.

The vented pistons on my tuba have extremely large vent holes, because sometimes fast slide/note movements can "outrun" the ability of undersized vent holes to vent the pressure.

I've only bothered to vent the pistons correlated to the slides that I move when playing.

Venting rotary valves (as are found on your 184) is far simpler and far less risky than venting pistons...an approximately 1/16" diameter l-o-n-g (like 12 inches long - available on special order) drill bit, along with a steady hand...and not too much pressure towards the end of the drilling...does the trick for rotary valve venting. The holes on rotors are drilled in the casings...centered between the two "slide loop" tubes exiting the casing...but approximately 1/4" or so above or below the two tubes' closest point. (A picture would be worth 1000 words, here.)


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