I've been trying to think of a way to describe the sonority of the NOT-the-fattest-belled/NOT-the-fattest-bodied ("classic" vs. "r̶e̶s̶e̶m̶b̶l̶i̶n̶g̶ ̶6̶/̶4̶ ̶Y̶o̶r̶k̶ ̶b̶o̶d̶i̶e̶s̶") German "kaiser" b-flat tubas that I've played
(tall, rotary, large bore, "smokestack" bell, NOT huge bell diameter).
Here is what I've come up with:
in fewer words (but words which mean less to more people)..."bright", yet "covered"a tuba with a characteristically 'bright' sound, YET played back on a recording with the bass knob turned up all the way