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subwoofer problem

H

hunter33

Limp Gawd
Joined
Mar 8, 2007
Messages
298
I have an older USA made Kenwood subwoofer and like it a lot. It's very heavy and sounds great.

A couple days ago the speaker would start vibrating randomly while watching a movie. It just started out of the blue in the middle of a movie. I unhooked the sub, pulled the speaker and amp out of the enclosure, and can't see anything physically wrong with the speaker or amp or anything.

Even if the volume and crossover frequency knob are turned all the way down, if the sub is on at all you can lightly tap the metal plate the amp is mounted on in the back of the enclosure and there will be "feedback" and vibrations out of the speaker. Again this is with the volume and crossover turned all the way down ... all you have to do is tap your finger lightly anywhere on the sub enclosure and the speaker will vibrate as if it's receiving a signal. Also there is a "thump" out of the speaker now when I turn the sub on. I tested the speaker with a multimeter and it seems to check out, and the speaker is not even very old. (I just replaced the speaker itself a few months ago when the cone wore out on the original)

I'm guessing the amp is done for or the output transformer is going bad or something. Any ideas on what might be causing this? I do have a 4 ohm electric guitar amp speaker I could hook up to test it with to be sure, but I'm afraid I would blow the guitar speaker in testing. Probably just going to have to buy a new sub but I really like the way this one sounds and would prefer not to.

Any advice would be very much appreciated.
 
i have a paradigm sub and it started to do the exact same thing, i thought it was my sub, but i brought my sub in to my dealer and tried it on another amp and it worked

so what i would tell you to do take your sub to a a/v store ask them if you can hook up your sub to a new amp, and check it that way.
if your amp is still under warrenty you can prolly send it in,

DO NOT USE YOUR GUITAR SPEAKER TO TEST IT.
 
It does it even if it's not hooked up to the receiver. All I have to do is tap the enclosure anywhere and the speaker will start vibrating and thumping.
 
hunter33 said:
It does it even if it's not hooked up to the receiver. All I have to do is tap the enclosure anywhere and the speaker will start vibrating and thumping.
Click to expand...

yeah all powered speakers or subs will make vibrating or thumpings if the cord is touched by some ones fingers, other metal, ect.

like i said it might be your sub it might be your amp, only way to be sure is try your sub out on another amp.
 
I'll put it back together and try it on a friend's amp just to check. The receiver is an Onkyo that is a few years old and I'd say it's out of warranty by now. Thanks
 
ok sounds good
keep us posted on the sub, but like i said you might have to buy either a new sub or new amp. or get it fixed
 
Well, it's fixed :D I put the speaker and amp back into the enclosure and turned it on and it was still doing the same thing. If lightly tap the enclosure anywhere there would be thumping and vibrating out of the speaker. I was close to throwing away the amp and looking for a replacement, so I decided to see what would happen if I hit the enclosure sort of hard on different sides. Thumping the enclosure in different places on the top and side were making the speaker do different things, so I started hitting it a little harder. At one point I hit it pretty hard on the side and the speaker quit thumping and the power switch was clicking. I hit it hard on the top, and everything seemed to be back to normal then.

Took it upstairs and hooked it back up to the HT system and now it's working perfect again. Go figure. :rolleyes: I wouldn't recommend this troubleshooting "method" to others, but I guess a switch was stuck inside it or something.
 
My subwoofer did that when the signal cable to it was partially shorted. It might have had an internal short that you got rid of by whacking.

Either way, glad it works again! :D
 
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