Question: why is my subwoofer smoking?

[miwingman]

I recently received a polk audio psw 140 powered subwoofer from my uncle. I went to plug it in to the wall just to test it with the line level input and the sub hummed very loud as soon as I plugged it in followed by smoke coming out of rear sound hole. not sure what caused this, fairly new to the speaker and sound hobby just wondering why this happened and if it could be fixed.

 

[nigelwright7557]

Sounds like output transistor(s) blown allowing through power rail into speaker hence loud hum.
It needs to be turned off as quickly as possible or the driver voice coil will fry.

 

[MAAC0]

Congratulations !! You received a poisoned gift from your Uncle.
Take the driver out and test it with another amplifier.
If it's OK You can try to repair the amp.

 

[scott wurcer]

It needs to be turned off as quickly as possible or the driver voice coil will fry.

Sorry but I had to laugh, I don't think the internet works that fast. I got a pair of NHT-1's where one woofer was literally inverted having been shot out of the enclosure, I hear they are doing well now.

 

[nigelwright7557]

Sorry but I had to laugh, I don't think the internet works that fast. I got a pair of NHT-1's where one woofer was literally inverted having been shot out of the enclosure, I hear they are doing well now.

I only ever fried once voice coil.
I noticed it was half as loud as the other speaker. It was only when I tested it with a DMM that I spotted it was half impedance.

 

[scott wurcer]

I only ever fried once voice coil.
I noticed it was half as loud as the other speaker. It was only when I tested it with a DMM that I spotted it was half impedance.

I didn't fry them but the seller said one channel had no bass, when I removed the grill the dust cap was sticking out and the voice coil was totally out of the gap (open circuit of course).

 

[nigelwright7557]

They tend to fry the resin around the voice coil and short out.
Sometimes the front of the speaker comes out and the voice coil unravels in the back of the speaker.
I once watched a youtube video where someone applied mains to a woofer until it blew.
Here is someone abusing a subwoofer.
YouTube

 

[scott wurcer]

Here is someone abusing a subwoofer.

That's funny, I think mine was shorting to a 100V rail with no fuses.

 

[rif]

It's been hanging around with the wrong crowd during recess.

 

[BennyD]

They tend to fry the resin around the voice coil and short out.
Sometimes the front of the speaker comes out and the voice coil unravels in the back of the speaker.
I once watched a youtube video where someone applied mains to a woofer until it blew.
Here is someone abusing a subwoofer.
YouTube

I saw that video too. Caused a bit of an uproar from what I remember. He did it as an experiment. He only wanted that diver for the frame and magnet assy. He has a few others for his setup and buys them damaged or not. He has them all rebuilt. He wasn't going to run it like it was anyway.

 

[JMFahey]

I repair and make Musical Instrument amps and speakers and *often* see speakers catching fire or carbonized voice coil or with wire torn off from former or ... or ... or ...

DC is more damaging than anything else, by far.

 

[Bern Wansen]

ive seen smoke coming out of a woofer because some sort of lubricant or solvent was used as a special curing agent during the restoration process and it evaporated from time to time lol