kadleck

Bob -

Wow - there can be a million reasons for that. My first guess would be that maybe you are not supporting properly. Or are you possibly over blowing?

Is it certain notes, or is it flat across the board?

I do have this same problem when I'm coming back from a lay off or vacation. Then a few days later when my chops are strong, it goes away. I also (unfortunately) play with my tuning slide fairly far out, so when I'm not in the best shape upper register flatness is really pronounced.

Try to give us more info if possible.

Thanks -
Tony