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What happens to the horn when a knowledgeable designer puts a larger (maybe 15%?) bell on a tuba?

It costs 15% more

As you may've guessed, I'm more interested on the impact on sound, projection, intonation, and shift in base tuning (if any).

It really depends on the body of the horn, and the qualities of the bell aside from size. It could open it up to give an organ-like quality, or it could cause it to go woofy. Pitch might improve, or it might go south. (possibly not a huge impact on pitch, realistically, unless the length of the throat is not right.) It could cause a huge increase in projection, it could cause the sound to be less focused and drop right in front of the player and stay there.

Too many things to really say, frankly.

This is exactly why prototyping is so important in horn design. You can sort of speculate what the results might be but you're not going to know for certain until you give it a try.

sailn2ba wrote:What happens to the horn when a knowledgeable designer puts a larger (maybe 15%?) bell on a tuba?

Specifically, what is it that you want to do?

sailn2ba wrote:What happens to the horn when a knowledgeable designer puts a larger (maybe 15%?) bell on a tuba?

Depends, too, on where the 15% is. Diameter, probably nothing. Throat, perhaps an entirely different horn.

sailn2ba wrote:What happens to the horn when a knowledgeable designer puts a larger (maybe 15%?) bell on a tuba?

Well, Besson/B&H, when they introduced the Sovereign, arbitrarily changed from the older 17 inch bell to a 19 inch bell without doing anything else initially. The horns all played flat and needed the "cut" of various sorts until the bugle was reengineered for the larger bell.

Thanks. I'm specifically talking about the Cerveny 681 15.7" and the Cerveny 686 17.7" bells on tubas with the same bore and wrap. Looking at photos, the bell throats appear to be very similar also.

You can come on down to SC and play my 686.