Work on voicing. If you haven't already started this with your teacher definantly start. Your sound, aside from your set up, is all about your airspeed and throat control. Think of the sounds ohh and awwhhhh when playing. You really have a brightness problem with a soloist? weird.

as far as setup goes Legit players usually use rovner light and ZZ vans. That could at least be a good place to start. Keep the jave 3 and the dark for your jazz setup. Concerning tone. Alot of players loose their tonal focus in the top end. When your playing that altisimo A just remember it needs to have the same quality of sound as second space A should have. I usually will play long tones of both and compare all of them (did I mention A is my favorite note on Sax?) . Did the altisimo A or Above the staff A sound as sweet as the second space A? Does it have the same fullness? With a tuner, are they all in tune? If they are out of tune, are they all in the same area? Like all slightly flat or sharp? You can't allways be exactly in tune, but you at least want to stay consistant. Or know that certain notes need special attention. For instance, are you biting to cause the upper A's to go sharp? The bad news is not only are they going sharp, but if your closing the reed your shutting down your sound. Keep that throat open and thouse teeth away from the reed!! I tend to tune as close to in tune as possible, if anything a little flat. That way if the concert goes long or I am getting tired I don't go sharp. Ya the sound will still suffer from the closed airway, but at least the pitch is still manageable. If you tune sharp, and your airflow closes, your justing gonna go sharper. So now your gonna have a weak sound and stick out like a sore thumb.