Posted by Kenneth Sloan on September 29, 2003 at 19:00:13:
In Reply to: tone quality change posted by lan on September 29, 2003 at 18:04:40:
You changed from one tuba to another.
one aspect of that change was that the first is in BBb and the second is in CC.
There are probably others.
I can't think of any particularly good reason to think that the pitch of the instrument is what is causing your change in sound.