Woofer damage from new Star Wars THX DVD?

YOW !!!! This makes me want to run out and buy this DVD just to see how much "devastation" i can accomplish. Thanks for the warning : )

As to the damage done to the JM Lab's, i would raise hell with your dealer and the importer. Ask them how some little "weenie" speakers can achieve THX certification and take the beating while these supposed mega-dollar speakers explode when pushed hard ? Covering only ONE driver ??? Talk about a "K-Mart" warranty.

Personally, i would do whatever it would take to get them to cover the damage under warranty and then sell them. Who wants a speaker that you can't watch movies with ( regardless of the type of soundtrack ) and / or get a hassle from the manufacturer / dealer when it comes time for them to stand behind a multiple thousand dollar product ?!?!?!? As to ONE of the woofers costing $1200, that is utterly and completely ridiculous. I hate to add insult to injury, but it is this kind of stuff that absolutely makes me abhor much of what "hi-end" has become. Sean
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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
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I did the same thing Will. I could not understand how that could damage ANY system, even at massive volume. I turned my pre / pro up seven notches higher than normal ( and i like it LOUD ) and nothing even flinched. There just isn't that much bass during the opening THX "electrified exploding sphere" sequence. Something is really wrong somewhere. To blow up a driver ( let alone two ) with that big of a motor structure would really take a lot of brute force over an extended period of time. Either the drivers themselves should have never been shipped out the door ( defective ) or the amp has got BIG, BIG problems. Sean
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Spluta: As i mentioned above, feeding a high level signal that is below the point of resonance to a vented speaker system will cause the woofer to throw wildly i.e. make excursions that can be dangerous to the woofer itself. I doubt that this is the situation with this specific case though as there really isn't a great amount of deep bass in the THX intro to that movie. Sean
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