The two pitches of bass tuba are often used interchangeably in different countries according to the local culture, but at least to me sound very different instruments. I thought I would just share my thoughts as I don't think many people play both to really compare. I certainly never fully appreciated the substantial tonal differences!
I am not saying one is better than the other, but just they are different. The tone of one may best suit one piece and the other another.
For the difference between F and a CC BAT, or BBb Kaiser - that is so huge I think they can be considered completely different instruments, quite as far apart in tone as say a violin and viola. No wonder the Germans are so strict about which is used for what music - can make a noticeable difference to the sound of the orchestra.


