Anahata wrote:
Arny Krueger wrote:
Close to my heart right now because I found a dead stage
monitor last night, no doubt due to an overdrive accident
that happened since last Sunday. I'm not sure what happened,
but the woofer was toast.

So much for all these theories about clipping producing harmonics which
burn out the tweeter. I've never really bought that as an explanation:
to do that the clipping would have to besevere enough to trash the sound.

Yes, it does have to be severe enough to trash the sound. I go to
concerts _all the time_ where the sound has been trashed.

I have worked with PA guys who turn the sound up until they can hear
the system clipping. That's how they know it's loud enough. They
judge the operating level by the amount of clipping. Give them a
system with a lot of headroom and they just keep turning it up and
complaining it doesn't sound loud to them.

Thanks for a set of much more plausible explanations, especially the
point about clipping causing compression. It's the thermal effect of
those average levels that's doing much of the damage.

That's right. Speakers blow for two reasons: thermal effects from
lots of signal that can't be reproduced, and mechanical damage from
exceeding excursion limits. One is a slow effect, the other is a
fast effect, and because of this there are two protection mechanisms
required on speaker cabinets.

I'd guess that a heavily compressed sound with low peak-average ratio
could also be a hazard for speakers, even if the peaks never clipped the
amp.

This can be true, but in this case you have the speaker ratings to tell
you how much power you can safely put into the cabinet. The problems
start when you start putting stuff into the cabinet that is either too
high or too low for the drivers to reproduce. Poor crossover design
can also be an issue here in that it can allow drivers to see signal
that is too high or too low for them to handle at a given power level.
--scott

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