TubeNet

Good sirs and madams, why can't rotary valve sections also have the 5th valve farther back? Why is it different than with pistons?

Tradition. They are built this way for decades, and now the manufacturers do not want to produce something which nobody will buy. Because nowbody buys it now. Because nobody makes it. So nobody buys...
If one of the great players would order this for his own horn it would be possible to launch it as a signature model. But a lot of buyers are very traditional, too. When Miraf/phone launched their Presto System many years ago (improved linkage for rotary valves. Bloody good and a space age look) nobody ordered it. For the look...

Usually rotors are larger bores than pistons. With a 4+1 piston/rotor setup the rotor goes in further back than the pistons because the bore expands more, allowing a rotor with a significantly larger bore size than the piston to fit in. With a 5 valve rotary tuba, while the bore can be graduated, they're generally all going to have similar bores that don't expand very much from one to another, instead of 4 similarly sized rotors and then one huge rotor (generally rotors have larger bore sizes than pistons to begin with, so this 5th rotor would probably be huge, especially if the other 4 are already of a significant bore size). Basically, it's all about expanding the bore size as the instrument's length increases (conicality)

Hope that's helpful

Pretty simple, really. COST - As done now all can be mass produced - make a variation production costs go up.

Thanks for the input, everyone.

barry grrr-ero wrote:Good sirs and madams, why can't rotary valve sections also have the 5th valve farther back?

Like my Cerveny Harmonia CFB 654-6 with big quint- valve?

a picture of an other CFB 654-6:

https://www.ebay.com/itm/Professional-f ... 7675.l2557" target="_blank" target="_blank" target="_blank

That's a groovy looking Cerveny.

This Gronitz F tuba has the fifth at the bottom (but a 6th at the top!)

https://www.hornguys.com/products/groni ... ary-f-tuba" target="_blank

Wade, I wonder where that tuba ended up? It was sold here on Tubenet almost yearly, but not for a long time now. Hopefully it has found it's forever home!

I wonder where Marty ended up? He used to post here on Tubenet almost daily, but not for a long time now.