My trumpet instructor, when we work on high range studies, says the key to mastering the high range is to arrange my tongue so that it forms a kind of arc that funnels the air straight into the horn. He likens the effect of this tongue to two rocks in a river funneling the water quickly between them, while the rest of the river flows slower.
Specifically, he says that the tip of the tongue must be generally placed on top of the bottom teeth, and the tongue must arc so that it can funnel the air to a greater velocity. He says that Allen Vizutti uses this method and that every professional player in Nashville uses this method as well. We attended a class by Allen Vizutti, and Vizutti essentially echoed my instructor's instructions.
I happen to play with my tongue resting at the bottom of my mouth, and I have a good high range and good tone, but my instructor and I are insistent that I adopt this method.
I just can't get it. For now, my instructor says to keep the tip of my tongue in the aforementioned area, and he says perhaps I will begin to get it right subconsciously.
Edit: My instructor is my best resource; I understand, but if the directives are said differently, or a small modification to the method is suggested by one of you, you guys may be providing help my instructor could not. Cheers!