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Can one get factory parts for local add-on to 4-valve tubas that have factory-installed 5th valve versions? . . like Miraphone 1291, Cerveny 686, VMI 3301, etc.? Is it practical to consider this option, or are the horns constructed differently at the manufacturer?

The Cerveny site used to have illustrations of 3 rotary valves tubas clealy showing straight tubing above the valve block allowing for the addition of 1 or 2 more rotors. This illustration is less obvious, but still shows the place where the 5th rotor will be placed on their 5 valve variant:


With 4 pistons’ instruments the potential position for at 5th rotor may be tougher to tell. Such rotors have been seen in 3 different positions on various models:

Right before the piston block like in the CB CC and in the Rusk cut CC’s of same inspiration.

Right after the piston block and before the main tuning slide.

After the main tuning slide like in the Conn 5XJ models.

Klaus Smedegaard Bjerre

THANKS. I'm not about to tackle installation of a 5th valve myself, and I'd have to be really choosy about having a tuba repair person do it. I'm just trying to figure out what the options are, as availability on the market seems pretty thin.