Posted by Lew on June 14, 2002 at 14:52:48:
In Reply to: Bore sizes and other measurements... posted by InkyDaveB on June 14, 2002 at 14:02:46:
Bore is a measure of the inner diameter of the cylindrical part of the tubing. This is usually measured as the inner diameter of the second valve slide. Most tubas have a constant diameter of all tubing in the valve section and have a bore between 0.620" and 0.840" (it is shown as a fraction because it is a fraction of an inch). A smaller bore horn can more easily be "overblown," meaning that the sound can break up more readily.
Everything else being equal, the notes on a smaller bore tend to "slot" more readily, meaning the pitch center is relatively narrow. This is good if that pitch center is where you want it to be, but it can make it more difficult to adjust for intonation issues. Larger bore horns tend to have more flexibility in lipping pitches, but this can make it more difficult for less experienced players to find the appropriate pitch.
Bell diameter impacts the "spread" of the sound. Again, everything else being equal, a larger bell can more readily produce more volume, but the sound tends to be less focused, and some have said that very large bells can make the sound seem muddy or unclear. Smaller bells tend to give a more direct, focused sound. Another factor that impacts this is the length and taper of the bell flair. A shorter bell tends to give a broader sound, at least to the player, than a taller bell.
The bototm line though is that finding the right tuba can't really be done by looking at the specs. Every tuba will play differently for each player. Generalities regarding bore, bell size and taper, bottom bore size, leadpipe length, and other tuba specs can't really tell you how a horn will meet your needs. I think that the best way to choose is to understand the type of playing that you will be doing, and pick an instrument that fits those needs, based on the experience of others who have been there. Ideally you should work with a teacher or other professional who can advise you as to which instruments to consider. You can drive yourself nuts looking at specs, and won't necessarily find an answer.