1) "Beyond your hearing" ---- may not be ----- beyond your hearing. Many (most?) audiologists measure dB down at THRESHOLD. I propose that hearing that is, say, 10 dB below normal at 15 K at THRESHOLD (and "normal" itself is down at high or low frequencies especially at threshold) may only be a few dB below normal at 85 dB, which may be about the SPL of the high frequencies during a 110 dB orchestral climax, with millisecond leading edge peaks that are much higher.
2) I've always wondered if something that measures "flat" with steady tones or sweeps from an audio oscillator is still flat when measured with transient bursts of high amplitude and known frequency characteristics. Since electro-mechanical transducers (JBL's buzz-term) are put under more strain (presumably) by steep wavefronts at high SPLs, maybe they treat the frequency spectrum differently at those high levels. And cones, domes, and diaphragms in compression tweeters may systematically differ by design type in their abilities to maintain flat frequency response during these transients. Anybody know?
3) The differences in the reproduction of cymbal crashes often show up great differences in components IMO -- is this related to the two points above?
Vman71: As to your 075s (JBL's original "bullet tweeter" or "orange juice squeezer"), there were long controversies in the 1960's & 70's as to which was better, the 075, or the Electrovoice T35 (which, when hand selected and paired, became the K77 series of Klipsch tweeters and is in the Klipschorn, and La Scala II to this day). About half the people with an opinion that I came in contact with favored each, Many pointed out that there was a tendency to turn the 075 up too far, making it harsh. That sort of thing maybe why PWK refused to have balance controls on his crossover networks, One engineer claimed that the 075 had a big peak at about 11K. Another, John Curl, who became star amplifier designer at Parasound (Hi, John!) said he preferred the K77, but didn't have extensive experience with the 075. This was waaaay back when he worked briefly for Joe Minor's Berkeley Custom Electronics. I was an advocate of the 075 back then, because it seemed so *** clear! Both could be screechy with bad Lps, but were great with good recordings. I finally had a chance to hear them both in the same room, in their respective speaker systems. The crossover for the 075 cut it in above 7K, and the K-77 cut in at 6K -- couldn't do anything about that difference. My impression after protracted listening was that the K-77 was warmer, and the 075 could be either clearer or harsher, depending on the recording.