nothing on differences on sound quality
My problem is air support; march up a hill or two (even small ones) and there just isn't enough air for me and the tuba - getting a decent sound isn't possible when you have to gasp for breath between each note. Add to that the need to play loud enough so the rest of the band can hear the tuba, even though they're a lot further away than usual, and marching gets to be quite a chore.
You could probably make a good case for using a brighter sound for marching, going for projection to cut through the rest of the band, rather than trying to balance them with dark-sounding massive presence; For me, this is purely a matter of air supply - I just can't generate "big, warm, slow air" on the march, so the dark sound is beyond my reach. I don't have enough control to change my sound color at will, so if I was going to be doing many parades, I would be shopping for a moderate sized mouthpiece (to conserve what air I have left) with a shallow cup (for a bright sound) and a wide well rounded rim (for comfort and endurance - pity about the articulation).
It's not so bad when you can line up several tubas, like the British band I used to play in (twenty five players, and FOUR of them were tubas), but marching is no fun at all when a lone tuba is trying to support a band of forty or more. I have to confess it was a huge relief when the old guard in our community band voted to hand over Remembrance Day to the youth band.
For concert playing, I try for a big, dark sound with massive presence, that puts a foundation under the band - most of the time the tuba parts are written for contrabass, and need to be felt rather than heard (not quite brown notes, but tending in that direction). My 4v-EEb and I need all the help we can get in the contrabass octave, which calls for a deep mouthpiece with a fair amount of funnel in its ancestry; I'm currently trying a Denis Wick 2, which seems promising (the DW3 is too bright). If I can't make that work, I'll just have to practice some more; when totally desperate, there is always the mouthpiece safari (yeah right, after I win the lottery).
