Woofer damage from new Star Wars THX DVD?

Sean, you said it perfectly. What the hell has become of High End? Smoke and mirrors man, Smoke and mirrors!!

Bishopwill: You mentioned something that i thought of also, but doubted ( or at least hoped ) that Avimar's amp ( Halcro ) wasn't failing in the manner that it would take to pop the woofer. I also "assumed" that the woofer of a "good" speaker would be strong enough to take "abuse", yet they did pop.

During severe clipping, some amps will pass sizable amounts of DC voltage. Putting DC voltage into a speaker is akin to instant "thermo-nuclear" heat build-up in the voice call. Adding sizable amounts of music ( AC ) on top of the DC heat being developed during sustained clipping and you can literally "melt" the windings of the voice coil of a driver. In severe situations, one can literally "flame out" a driver i.e. you see flames coming out of the speaker cone near the dust cap ( circle covering the voice coil ). If you ever see this happen jsut once, you'll never forget it. It will initially scare the hell out of you. GUARANTEED !!! Once you've dealt with the situation and the shock has worn off, your memory will be of an "awesome" event i.e. the stuff that "audiophile tall-tales" are made of.

As it turns out, my girlfriend borrowed the "Attack of the Clones" disc from her mother this last weekend. I'm going to fire it up later this week and see what happens. My guess is that i'll be fine due to the fact that i'm running sealed speakers. I'm thinking that the center frequency of the "blast" is tuned below the resonance of the port on most speakers, which causes the driver to become "unloaded" at very high volume. This results in the woofer flailing about wildly with the amplifier offering little to no control. Obviously, this is VERY tough on the driver and sometimes results in complete and total devastation of the driver(s).

If you think of a badly warped record being played on vented speakers, you might be able to picture a SMALL part of what is taking place. The same thing is taking place, but on a much more intense and consistent level. This can take place in a subwoofer just as it can in a "standard" speaker. That is, if the subwoofer is vented ( port, passive radiator, slot loading, etc... ). In a sealed and stuffed speaker system, the natural "air spring" within the box helps to minimize "bass slop" / excess excursion and keep the driver under control. Sean
>

I have no reason to doubt the above posts about speaker damage resulting from the Star Wars DVD, but since 100,000s of copies of this disc have been sold/rented, then why aren't we hearing reports in the media of tens of thousands of damaged HT setups? If this disc is causing damage to high end speakers with hefty power handling capacities, then I can only imagine what its doing to a typical sub $1,000 real world system.

I would think that there would be little chance of "real world" setups being affected, simply because either most low end amplifiers don't have enough power to blow out a speaker like that, or the systems don't have enough bass extension to even attempt to reproduce uberbass like that. It's only gear that's good enough to try and powerful enough to fail spectacularly that causes problems . . . .

Hmmm....
A 36 dB increase from what level? There's gotta be a reference point somewhere, right? And the frequency(ies) of attenuation might be better info to provide also.

But quick advice would be to check the disc vs. another. I'm sure SOMEBODY else besides you bought it. Distortion, rather than dB level might also be the problem. Whether produced by source, software, or amplifier (gain stages, yep!), the distortion is much harder for the amplifier to control than a clean over-emphasized recording.

Threatening the speaker manufacturer with negative newsgroup postings might get you some sympathy. Or maybe organizing a petition if enough people have actually had damage occur, you could contact the disc manufacturer. Keep accurate records either way. I'm curious.
As with most software, I would assume that the manufacturer only warantees the product, NOT the aftermath. Or connected components.

Back to the 36 dB issue.... WHERE did you hear this?

And lastly, if the SPL was enough for you to consider hearing damage..... Maybe you have a class action lawsuit on your hands. George Lucas probably has some mighty deep pockets. Of course, he might counter-sue because your Utopias aren't THX-Ultra II rated. Nor was the amp or the cables.