If the wood is preserved by deeply saturating it with, say, epoxy, there's nothing inherently different about this than any other composite material. It would need to be deeply saturated to protect the wood from moisture.
Valve tolerances and dimensional stability will be a challenge. I would soak the wood in a penetrating epoxy and then machine it, depending on the epoxy to control moisture content (which is what causes dimensional instability. But in the end, metal valves might be a better answer.
Acoustically, there is nothing about this, especially if really soaked in penetrating epoxy, such as Clear Penetrating Epoxy Sealer (
http://www.smithandcompany.org/CPES/), that should play similarly to a fiberglass or carbon composite instrument, and those materials have proved successful at least at some level. The material will certainly resonate differently at high frequencies, but we really don't want tubas ringing at those frequencies anyway, in the way that we do want it for some higher brass instruments. Low frequencies, including all the dominant overtones in tuba sound, will resonate in the space of this tuba effectively enough.
I recall one of Brian Kane's plastic tuba getting a review of it from a top performer. The performer's judgment was: There is nothing wrong with this tuba that is caused by it being plastic. The implied statement is the shape has to be correct no matter what the material, or it's not the material's fault if the scale is wonky because of the shape.
I also sat next to Art Hovey at an Army Workshop reading session a couple of years ago, and listened to him play his plastic Tiger Tuba, or whatever it was called. Despite all the constructions he'd added to manage the inherent unreliability of plastic valves, the instrument
sounded like a tuba. Art did not claim to be working any magic as a performer to make it so. I wish I had sounded remotely as good on my Hirsbrunner.
So, if the shape of this wooden tuba is appropriate, I would expect it to sound like a tuba. It would take a lot to make it reliable for daily use, but I think it could be more than a beautiful tuba sculpture.
Rick "York's Magic Brass (tm) notwithstanding" Denney
