iiipopes wrote:Chuck(G) wrote:Here's one that I've wondered about.
A lot of makers who put the 5th valve after the 4th (piston) valve make the bore on the 5th larger. So, if one were to put the 5th ahead of the first, would there be an advantage to making the bore through the 5th slightly smaller than that of the first piston valve?
I don't know -- anybody know how it was done on the Getzen/M-W?
I had a CB-50 for several years.
The 5th valve was indeed a small rotor mounted before the 1st piston in the very short leadpipe. It was a small diameter rotor (notably smaller than the standard MW 5th valve included with most of their "big valve" piston CC tubas), but I do not know the bore. The pistons on the CB-50 were .689, small by modern tuba standards, though the Conn 5xJ series is .687 (yeah, I know...the difference is very small). So, I'm not sure how much smaller the bore of the rotor could have really been, but I never measured mine with my calipers and no longer own it
I thought the CB-50 played great (I just
had to have something bigger, so I sold it) and that the 5th valve notes and the low register in general were very responsive and easy to play. It did take a while to get used to the change in the feel of the instrument suddenly having a couple of extra feet of tubing in the leadpipe every time you hit the 5th valve though.
What did not work really well was the highly touted "BBb conversion," in which the the 5th valve was flipped to turn the horn into a BBb. The valve slides were long enough that they could all be pulled to make the thing play in tune, but it played awfully stuff with air constantly being redirected through the tightly wrapped 5th slide such a short distance into the leadpipe.
BTW- A few years ago I remember seeing a Hirsbrunner HB-2p at Dillon's that actually had the 5th valve in the leadpipe before the piston cluster from the factory. I did not ever play it and I do not know where it ended up.