Woofer damage from new Star Wars THX DVD?

Spluta,

You said 75db do you mean the display on your preamp shows 75db? If so, that is not how the setup works. You can not go by the number on the display because different power amps and speakers have different sensivitives. You need to run a test signal and measure with a SPL meter at the listening position. Someone said it should be 85db, some said 75. I don't know what is right but I will go by the lower number just to be safe.

On the other hand, if you did measure with a SPL and your speaker begain being stressed than I think your room maybe too large for your speakers. A speaker should not show stress at 75db at the listening position.

My comments were based on what I understand from your message. I could be totally wrong here because I don't quite understand what you meant by 100db for busy redbook and 105db for DVD-A.

Im saying my SPL meter is reading 75db's for all
7 speakers when i have the volume set to a high
level... the same level that produces 100db two
channel and ect... The test pattern is not as loud
as a real source cd, dvd ect..

The test pattern goes around in a circle and i adjust
level for speakers one by one to achieve proper level.
I believe it has nothing to do with how loud it is
for the test signal. Just that all of them match up.
So what im saying is all 7 speakers are set to the
same output levels. Is this right?

My speakers dont start showing stress until 100db's
with normal source material. I think there doing well
for size..

I dont listen at those levels for any prolonged period of time.. And i certainly dont watch movies like that..
I have a little bit of hearing left and im trying to hold on to it. (lots of loud gigs... Ive played electric guitar most of my life).

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
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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.