Woofer damage from new Star Wars THX DVD?


Both woofers in my JM Lab Utopias blew with the THX intro (exploding sphere) on the new Star Wars DVD. Happened at normal listening level through my Theta Casablanca II/VTL 7.5 preamp/Halcro dm58 amps. I've not blown a driver in over 30 years of being an audiophile. I've heard that the base was boosted as much as 36db on some of these DVDs. Even though the speakers are under warranty, I'm out $1,200 for a new Focal woofer (JM Lab only covers 1 driver for this kind of damage). Anybody with information or suggestions? Needless to say, I'm not happy about eating this expense if the fault really lies with an overmodulated DVD with no warning about increased bass levels. At the verey least, I'm curious to see if this happened to anyone else. The sound level was high enough that the concern for hearing loss came to mind (I'm a physician and I don't think I'm this concern is frivolous). Thanks for any thoughts or other input.
avimar

Showing 1 response by slartibartfast

Spluta- You probably don't have your system set to video reference levels. When properly calibrated, you will see transients (as per the spec of dolby digital ex) well above 100 db. I believe 115 db is the transient max for Dolby Digital EX but I have measured some movies in excess of 120 db. With the Star Wars Attack of the Clones turned down a good 10 dB from reference, I am really taxing my MBL subwoofers. At reference level in a decent sized room, I can see how someone could blow a driver out on some of the explosions in the movie.

To properly set the reference level of your HT to movie theater standard, you need to calibrate each of your speakers to 85 dB with Avia when your processor is set to reference volume. Most processors set reference to 75 dB but this is innacurate.