Posted by Joe S. on March 11, 2000 at 01:19:51:
I finally figured out (not meaning to "try to", at all) how it could work:
The "switch" valve would be at the end of the mouthpipe tube. It would divert the airstream into either the (for the sake of discussion, say) CC or F tuba.
The F tuba "side" would consist of the four classic valves plus that hand's thumb would be responsible for the "switch" (F or CC) valve.
The CC tuba "side" would consist of the normally-found five valve set-up, once you were on that "side". It would be "fingered" by the left hand (assuming that the F "side" would be fingered by the right hand.)
Each "side" would have its OWN bell (two bells, total), and these bells would be very similar to each other, in order to achieve something approaching one "voice". The two bells would be side-by-side, for the same reason.
It would look ridiculous, would be impossible to play without a stand, and wouldn't fit in a normal sedan, unless the instrument could somehow be "broken down".
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As far as my thinking goes, no other "double tuba" concept is feasable. Tubas with long extensions of cylindrical tubing (as are found on "double" french horns) play disastrously badly. The "two complete tubas in one", sharing ONLY the mouthpiece and mouthpipe, is the only system that could work, in my view.
Don't ask me to build one...I have a life, and I have respect for my life...and don't ask me to play one - I am not a circus clown, either.