On April 5, 2014 at 13:43, Ernie Gilman said...
Back around 1980 I worked for Marantz, in Loudspeaker Engineering, when they had a real engineer there and proper test equipment for evaluation.
I learned there that cloth dome tweeters can only play so loud. It was crazy to record response curves at several volumes and see the tweeter output settle down to one particular volume level though the woofer volume was going up.
This was in the 80+ dB range, but well within levels you might occasionally play at home. I've not been in favor of cloth domes since.
If this was ~1980, you were working with Phillips, Peerless and maybe Vifa tweeters? The Phillips AD-140, AD-160/162 or Peerless LK-10DT or KO/TO-10DT tweeters (The KO-10 had a removable cover, to make diaphragm replacement easier)? I don't remember the Vifa models that had begun to show up, but these were probably the most common and they were decent, for the time, but until they started to use ferro-fluid, they didn't dissipate the heat well enough to avoid thermal compression. The Phillips AD-0163 DID use this and were able to do high SPL a lot better than the polycarbonate or textile domes without ferro-fluid. I have a pair of Jamo J-101 speakers with these and they never had any problems keeping up with what I played through them.
80+ db and you were running into thermal compression? I would expect that well into the 90dB range, especially if the crossover didn't cause too much insertion loss- the Phillips tweeters' sensitivity was pretty high. The Peerless, if it was the rectangular one seen in Polk and other speakers, wasn't so sensitive and was a bit too "polite" for some kinds of music.
Were you there when Marantz was making the Gold series, with the movable foam plug for the vent and/'or weights that screwed into the woofer's dust cap, to change the Q?
