I know this is old, but I would just like to mention that I have actually played F0 on a B Tuba personally using the standard 'buzzing' technique, so I can vouch for that note definitely being in the extended range of a Tuba. In principle, even a standard 3-valve Tuba should be able to play E0 a half step lower as long as the instrumentalist can 'buzz' that low. (Which is very hard to do, imo). 76.14.232.104