Posted by Jay Bertolet on March 19, 2001 at 17:25:07:
In Reply to: Re: Re: Re: Rusk Cut vs. Dillon Cut posted by Chuck(G) on March 19, 2001 at 11:51:56:
Isn't it true that piston valves generally have a smaller bore than rotary ones? If so, that explains why the 5th rotary valve can easily go on top of a rotary stack. The longer leadpipe associated with a rotary tuba opens to a sufficient size to accommodate the rotary 5th valve bore size. The debate with piston valve horns occurs because the leadpipe on those tubas is usually quite a bit shorter and that works fine with the smaller bore pistons. To accommodate the larger bore 5th rotary valve, you have to go farther into the conical expansion to reach that bore size, as in after the pistons and usually after the main tuning slide. I'd be curious to know how Rob Rusk managed to make those "in the leadpipe" 5th valves work so well, as they obviously do on so many of his creations. It seems counter intuitive that it would work, making the bore of the 5th valve markedly smaller than normal, unless he used overly large bore piston valves.
My opinion for what it's worth...