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HELP - How Hard is to Blow a Bass Driver

As I came home I see my little brother and his friend BLASTING a Prodigy song in my listening room. I don't know the song but it was about 1 MIN. of just full loud annoying bass only (the kind you hear in Honda Civics while the liscense plate is rattling). As I ran into the room to lower the volume I saw the Driver shaking like CRAZY. Not "in and out" motion but more like shaking erratically all over the place.
Amp is the Exposure 18(70 watts rms)
Speakers are the PMC Fb1
Volume at 12 o-clock

I'm concerned that there might be damage to the Drivers. I can't hear any damage but could there be internal damage (coils)that might show up later on? Any way to test for damage?

Thanks for your help as I am stil in a cringing state
dr_balance
unclejeff
1,313 posts
 
You probably dodged this one. I don't think that your exposure amp can terribly harm your PMCFb1s at this level. I suppose you could get one of those CDs that test everything, but I would not fret over it.

Chill.
drew_eckhardt
394 posts
 
If the woofers were making clanking noises, their voice coils bottomed, the formers may be deformed, and may now rub.

Otherwise don't worry about it.
morbius396c
134 posts
 
Dr. balance,

With a 70 watt amp - it's more likely that the upper frequency
drivers could be damaged if they overdrove the Exposure 18
into "clipping".

If the amp is driven into overload, and can't supply enough
voltage so that the peak voltage equals the peak input voltage
times the amp's gain - it will clip off the top of the wave
at its maximum voltage.

Because this means a sharp kink in the wave - that results
in a lot of high frequency distortion products which get
routed to the tweeters and high frequency drivers by the
crossover - resulting in fried tweeters.

Listen to your tweeters - if you can hear them OK - then
you are probably fine. Tweeters don't stand for abuse
very long - they just go "phht"

Sounds like you dodged the bullet.

Dr. Gregory Greenman
Physicist
dr_balance OP
16 posts
 
Thanks guy for the input. I was very concerned because I heard distortion. The song consisted of EXTREMELY LOW BASS only. The bass that was comming out of the Bass driver was driven into distortion, however for a short period of time only 30 seconds (my guess) whould that be enough time to cause any damage to either the bass driver or tweeter. I gently pushed the driver in listening for scraping sounds and it moves freely. There also doens't seem to be any damage when listening at normal levels. My question, however is, is it possible for there to be unheard damage that will show up later (ie, stress) or would I know right away if there was damage?
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