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well wise guy... i CAN tell you i USED TO be able to hear well over 20kHz as the "pigeon chaser" ultrasonic tweeter at a downtown bus stop used to cause me a high pitch stabbing pain i never was able to figure out until seeing the tweeter rotating in the rafter over my head. if anyone else was hearing it, they weren't cringing like me. a woman i used to ride the bus with couldn't hear it and argued that i was imagining things UNTIL i turned my back on the tweeter, that took a minute or more to make it's circuit, and called out when i started hearing it, and then 5-10 seconds later said "now" when it had gotten unbearable and was about 20-30 degrees off axis. that's not even the issue! extension to 40kHz is indicator of transient speed capability. you do understand basic physics don't you? the more massive an object is, the harder it it is to move AND the slower it will move for the same input in energy. that's why, despite the arguments of a thick headed former friend, a tiny flea actually pulls more Gs than a giant NASA rocket. if an object can easily moved at 40kHz, then 20kHz is no problem, as it has a superior power to mass ratio. THAT's why the RAAL ribbon has the absolute closest to a brick wall waterfall plot out of ANY speaker i've ever seen. start on a dime... stop on a dime... 40kHz? no problem. THAT's also why, even though they sound smooth and easy on the ears, MANY (especially the ones in NHT superzeros) soft dome tweeters suck so bad at reproducing cowbells even with an "above 20kHz 25kHz claimed extension". they just can't do metallic percussion. PERIOD! a good aluminum or titanium dome? much better, but i'd bet $1 a RAAL ribbon would really snap harder and faster. the pseudo ribbons in a large pair of maggies (which had serious resonance SQ & possibly amp matching issues) were painful to listen to at volume when the clocks chimed on my harvest dark side of the moon CD at volume. it felt like getting shot in the ears. so yes... 40kHz DOES make a difference. it's an indication of just how effortless changes in direction are for a driver. that's one of the reasons (besides wavelengths... i'm fairly well versed in the science) tweeters are smaller than woofers. it's harder to make higher masses move quickly AND precisely as once in motion, they're 2x harder to change the direction of, or as newton, i believe, put it, an object in motion will remain in motion until acted upon by an outside force. tweeters that can't even do 20kHz (most compression drivers) are simply too massive to vibrate any faster. simple physics kids. they're like massive 1970s all steel 4 doors whereas a tweeter that can do 40kHz is like a carbon fiber 12 cyclinder ferrari... lighter & more powerful. (power to weight ratio as it's known in drag racing circles) actually, a crotch rocket would have been an even better example as they have even greater power to weight ratios despite their much smaller motors. i've had this very same extension argument, just as i've had the SAME freakin' argument about the well known MULTIPLE forms of resonant DISTORTION inherent in bass reflex 100 times, about tweeters and the science behind extension and expect it will AGAIN fall on confirmation biased deaf ears that, pun intended, don't want to hear it because their EMOTIONAL response to a sound they find pleasing is more important than the science behind it. the only kind of tweeter i'm aware of that has an even better power to weight ration that stratosphere reaching ribbons of all types is an argon gas powered plasma tweeter which is extremely impractical and not very efficient. the next best thing is good enough for me. you're entitled to like whatever you like, but don't attempt to try and force it down my throat, which is ironic as only horns have throats.
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