Super tweeters. Like infra subs, they deal with the very extremes of the audible bandwidth. Basic human biology, the actual frequency response of musical instruments and Redbook's brick-wall filter would all propose that there's not much if anything to hear with either type of device. First-hand experience suggests something quite different. Of course exotic tweeters of the diamond, beryllium or ribbon sort already hit the—relative—bat sphere on their own. They're super as is. It's speakers with more conventional tweeters which the supers would seem to stare straight into their soft domes to, cue up the Jack Nicholson flick As good as it gets, complete them. That movie scene concluded with the gushing receptionist asking the Nicholson character: "How do you write women so well?" To which author Melvin Udall famously answered: "I think of a man and I take away reason and accountability." Ouch!