Posted by Rick Denney on September 03, 2000 at 15:52:47:
In Reply to: What does................. posted by David RN on September 03, 2000 at 14:34:42:
Rudolf Meinl had a specific system in place to categorize the volumetric size of their horns. All their horns are proportional to the bell size, so they rated their horns based on the bell size. Something like: 17" bells were 4/4, 19" were 5/4, and larger bells 6/4. But seems like Rudy Meinl was the only rotary tuba maker with such a wide range of horns, and most rotary makers used the term "Kaiserbass" for instruments larger than the standard full-size horn.
When the Yorkbrunner came out, it had bigger outer branches than most rotary horns, but the bore was smaller (as is the case with American-style isntruments). Looking for a label for marketing reasons, they started to use "6/4." Many rotary "5/4" instruments are as big as the so-called 6/4 instruments. There is no standard of volume, and how that relates to the nominal size of the instrument.
It has nothing to do with pitch, which is controlled by the length of the tubing. It has everything to do with apparent volume, and the sound of the tuba and what sorts of things it's good for.
I think it was Tony Clements who proposed the following description (with apologies to Tony for my poor memory):
3/4: Is that a euphonium?
4/4: Just a normal tuba.
5/4: Wow! That's a big tuba.
6/4: B.A.T.
Rick "or something like that" Denney