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Is anyone out there who prefers a small CC in quintet playing a 681?

I have played some 186s but not a 681. Is the 15.75 inch bell a plus or a minus?

The longer the tuba the more "umf". Even a small CC tuba will have more bass weight because it's lower the extra overtones.
So do you want more bass presence or do you want to be able to disappear a bit easier in the other players sound? If it's the later try an F tuba

I had a 681 CC as my first tuba. It sounded very much like a Miraphone 185 when compared back to back. The Cerveny is a compact 4/4 with a relatively large bore; although I rarely played quintets, I think it would be a great choice for a small group where you want a good balance and prefer to play CC.