I have a Besson New Standard 4 valve comp from 1967 with the 17" bell planning to be restored. I read in several posts that there were transition models existing with a 19" bell. Does anyone have experience with those instruments?
As the tuba needs some substantial rework anyway, I wonder if changing/enlarging the bell will help in larger orchestra settings where the 17" bell has its limits regardless of the mouthpiece. And yes, I am aware of the potential costs also in relation of the instrument's current worth

I am used to the 3+1 ergonomics for 20 years now and like the playing characteristics of the instrument very much. But I am looking for an even broader darker sound with more loudness reserve.
For all other settings I have a classic German Kaisertuba and also a small F-Tuba.
Thanks!