Well, since you are getting sound, I guess the Berg is not so open that you can't push enough air. Might try a Jody Jazz or Meyer rubber mouth piece with that horn. Ralph Morgan makes a great mouthpiece. The main thing about tonal quality is how you play though. Another person might get a much different sound from your set-up. I really recommend getting a private teacher. He might help you choose another mouthpiece, as well as give you proper exercises. The basic warm-up exercise for me is for breath control mainly. Just a chromatic scale, holding each tone for 6 beats @ 120, breathe for 2 beats, hold next tone for 6 beats and etc. The better your breath control and embouchure, the better you'll play in the end. I know this is boring, but do it over and over for 5-10 minutes before opening your practice book. Good Luck.