I've never been able to use the 120S -- it seems to suck the air out of my lungs. Over time (about 20 years) I also came to prefer the bowl (German) style tuba mouthpieces to the Hellebergs, though my go-to-will-always-work-on-pretty-much-any-tuba is the Schilke 66 (a comparatively "small" Helleberg). Many tuba players use (or try to use) a mouthpiece that's simply too big for them. The Wick 2 is a good "standard" size for the BBb for many players. But you might consider a 3 -- at least try it. It will give you more control and won't hurt your range. If you're playing a typical BBb Brit compensator, I would stick with a Wick. For my Eb I've found that the Wicks just seem to work a lot better -- which came as a surprise to me. If you're using a non-comp, a Wick should work fine; but you might want to experiment with others. Again, don't get sucked into the "bigger is better" approach to BBb mouthpieces. I'd say try a Wick 3 or something like a Bach 25 to see if you get better comfort and control. If you need to at some later point, you can always move to something larger -- if you NEED to.
Tuba is, in my experience, VERY different from euphonium; and you can't play it as just a "big euphonium" (just as you can't play euphonium simply as a "small tuba"). There's a lot more room for embouchure error in the larger mouthpieces, but you can also get away with more sloppiness in the middle and low registers. So concentration on embouchure is important to produce the best effect consistently. The whole feel of the instrument is different too, and that takes getting used to. The other recommendations in this thread are good pointers to addressing those issues.
Last edited by ghmerrill; 02-25-2020 at 10:20 AM.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)