Posted by jeff on February 23, 2004 at 19:59:00:
In Reply to: flat high range posted by need info on February 23, 2004 at 00:09:40:
A large mouthpiece will cause flattening in the higher partials of a brass instrument. If I recall my acoustics text correctly, this begins around the 6th partial (i.e. F above middle C on a Bb euph) and gets worse from there.
Maybe a smaller mouthpiece would help? It doesn't have to be just the rim aperture or cup depth - throat and backbore can influence this as well.