In article .com,
wrote:

that's interesting about ultrasonics and the tweeters "trying hard". i
thought if it was out of the effective band of the driver, the driver
would simply ignore the signal more and more because it can't "see" the
sound at that frequency range. but if i understand you correctly, a
driver might be trying to produce that sound.

Try it with a woofer, where the effect is easier to see. Sweep a tone
back and forth from 10 Hz to 2 KHz and watch what happens to the cone.

When the frequency is too low for the system to handle, you see the
cone break up, and you see massive excursion. When the frequency is
too high, you see a different kind of cone break-up, a lot less movement,
and the voice coil gets hot.

Get some of those $5 8" full-range installed sound drivers and give it
a try. It's lots of fun.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."