Posted by Jay Bertolet on August 05, 2000 at 09:28:36:
In Reply to: Re: Re: adding a dependent fifth valve posted by Mark in Ohio on August 04, 2000 at 23:19:45:
The horn I added a 5th valve to is the now infamous Cervany 601 I'm selling. The reason I had to add a 5th is because Cervany didn't offer a 5 valve version of the 601 at the time I bought mine. Even though I pleaded/argued with them about it, they refused to offer a 5 valve version. To add the 5th, I simply ordered from the factory a complete 1st valve assembly which comprised the valve and the valve tubing, already fully assembled. I also ordered two extra 1st valve slide crooks and some extra inner and outer slide tubing. These parts were reassembled to make the "crossover" design 5th valve that Rudy Meinl uses on their horns. If you want to see how this works, just look at any of their tubas with 5 valves. I think it is a great design that doesn't have the stuffiness that other 5th valves can have.
The reason I tell you all that is to answer your question about bore size. The bore on the valve was .835, the same as the bore on the 1st valve. Now, the fact that the bore on this horn is so large might account for the lack of stuffiness this application has. But I would think that if the valve did make notes it was used on more stuffy, I would still notice it. It did not. I've just been very pleased with the way it worked out and considering that Cervany later started offering 5 valve 601 tubas where the 5th valve was a half step instead of the standard whole step, I'm much happier with my rig than one of the new ones since mine is a flat whole step.
You mention "in-leadpipe 5th valve" in your response. Let me stress to you that this type of design is not anything like what I consider an in-leadpipe design to be. True, the valve is added to the top of the current stack of valves, just before the 1st valve, and is technically in the very end of the leadpipe. But this design isn't anything like some of the in-leadpipe designs I've seen (usually on piston valve tubas) where the 5th is just added where it is convenient and someplace other than the very end of the leadpipe. One of the strengths of this design, and why it doesn't affect the horn adversely, is that the valve becomes the last 2" of the leadpipe. If the installation is done properly, it is almost like the valve isn't there when the valve is not engaged. In any event, with the bore of your 191 being .830, as long as you have enought straight leadpipe just before the 1st valve, This design should work the same for you as it did for me. One thing I did was buy an extra leadpipe so that if things didn't work out, I could go back to the way it was and not ruin the horn. But all that did for me was give me an extra leadpipe to sell with the tuba!
My opinion for what its worth...