Posted by Rick Denney on August 07, 2000 at 13:13:57:
In Reply to: Re: Re: adding a dependent fifth valve posted by Mark in Ohio on August 04, 2000 at 23:19:45:
I keep wondering at the true importance of valve bore. Some horns seem to do just fine with a smaller bore, and others do just fine with a huge bore.
The fifth valve on my YFB 621 is in the leadpipe, but it's immediately upstream from the first valve and the same bore as the piston-valve tubing. I've never found the fifth valve to be stuffy in any way.
Adding a fifth valve of the same bore as the others to the conical tubing downstream from the others would constrict the bore, which would probably be a problem. Most of the graduated-bore horns use a larger bore for valves more downstream from the mouthpiece.
I also don't understand why a fifth valve has to be any particular place. That low F can't tell whether the valve tubing it went through first belongs to the fifth valve or to the fourth. The vibes see some conical leadpipe, some cylindrical valve tubing, and some conical branches on the way to the bell. It would seem theoretically sound for the upstream fifth valve to be the smallest bore on a horn with five increasing valves--a true graduated bore horn. Wasn't that magic B&S F tuba made that way? It's a fact of life that notes in the lower register use more valve tubing--this is anavoidable no matter what the configuration of that tubing. As long as the cylindrical stretch fits in with the taper plan of the horn, then it should not matter which valve it is.
Rick "The 621 fifth valve is certainly not stuffy" Denney