Fried subwoofer?

[mrjamiam]

A slow-moving thunderstorm earlier today led to a power outage here.  When power was restored, I heard an odd noise from my AV system's subwoofer.  It's nothing to do with signal - I disconnect the speaker cable and it continues.  Only removing power stops it.  It's a repeating, heartbeat kind of noise.  Or, since we're guitarists here, a slightly slow shuffle rhythm.  Also reminiscent of the sound from an LP when the side has played and you need to pick up the tone arm.

I'm assuming I'm screwed, and will need to replace the subwoofer.  However, I thought I would ask here if there were any knowledgeable suggestions, and I'm curious about what produces the noise.  Any ideas?

 

 

 

[JohnnyB]

2 hours ago, mrjamiam said:

A slow-moving thunderstorm earlier today led to a power outage here.  When power was restored, I heard an odd noise from my AV system's subwoofer.  It's nothing to do with signal - I disconnect the speaker cable and it continues.  Only removing power stops it.  It's a repeating, heartbeat kind of noise.  Or, since we're guitarists here, a slightly slow shuffle rhythm.  Also reminiscent of the sound from an LP when the side has played and you need to pick up the tone arm.

I'm assuming I'm screwed, and will need to replace the subwoofer.  However, I thought I would ask here if there were any knowledgeable suggestions, and I'm curious about what produces the noise.  Any ideas?

The "slow shuffle rhythm" sounds like the voice coil has warped or misaligned and is scraping in its gap. That leaves the question of why it's active at all if it's getting no signal?. For that I don't have an answer, but since it makes that sound when the AC is on, some components in the internal electronics--which includes power supply (filter capacitors?), preamp, crossover, equalizer, and power amp--may be letting line noise or AC power through to move the woofer. 

I installed a living room stereo in my next door neighbor's living room 11 years ago. A year ago we had an electrical storm that caused a power outage and then a surge a time or two before the power came back on. For reasons unknown my stuff survived, but his integrated amp stopped working and his CD player was playing, but making weird noises. When I pointed out that they were already 10 years old he decided to replace them. His subwoofer was unharmed. Point is, with power outages and surges and electrical storms, it's a crapshoot as to what will be damaged unless you unplug everything when it hits.

There are a lot of good affordable powered subwoofers these days.

[Thundersteel]

Your sub amp is probably fried. The speaker should be OK, but you'll probably want to take a look at that, too.

[mrjamiam]

Looks like I'm not the only one.  Not exactly the same noises mine is making, but not far off either:  

 

And even at the Polk Audio site:  http://forum.polkaudio.com/discussion/164850/psw111-sub-woofer-problems

So I've got someone to call, if I get around to it during business hours, which isn't always easy.  I guess I'm probably going to be shopping.

[tomteriffic]

As an alternative, measure the plate size of the amplifier and go to Parts Express.  They may have a suitable replacement amp for less than the price of a new sub.

[DaveH]

And, I'll throw this recommendation out there again... HEPD. Schneider (old Square D) HEPD's have dropped in price over the past several years, now they are so cheap there is no excuse:

 http://www.homedepot.com/p/Square-D-Home-Electronics-Protective-Device-HEPD-HEPD80/203540660

[Armitage]

Absolutely... everyone should have one (or similar) on their main panel.

[mrjamiam]

Thanks, folks.  I decided to get away from Polk Audio subwoofers because of the apparently not-uncommon problems.  I was able to find a recommended subwoofer for about the price of a new board from Parts Express, so I went that way.

I don't know that my problem was caused by the power situation - other folks online who post about the problem don't say anything about a triggering event, and besides, mine was on a surge suppressor power strip - but the whole house solution is very attractive.

[HSB0531]

On 6/25/2016 at 11:09 PM, mrjamiam said:

A slow-moving thunderstorm earlier today led to a power outage here.  When power was restored, I heard an odd noise from my AV system's subwoofer.  It's nothing to do with signal - I disconnect the speaker cable and it continues.  Only removing power stops it.  It's a repeating, heartbeat kind of noise.  Or, since we're guitarists here, a slightly slow shuffle rhythm.  Also reminiscent of the sound from an LP when the side has played and you need to pick up the tone arm.

I'm assuming I'm screwed, and will need to replace the subwoofer.  However, I thought I would ask here if there were any knowledgeable suggestions, and I'm curious about what produces the noise.  Any ideas?

 

 

 

Yes:

Power Supply caps got toasted.

[HSB0531]

On 6/27/2016 at 5:15 PM, DaveH said:

And, I'll throw this recommendation out there again... HEPD. Schneider (old Square D) HEPD's have dropped in price over the past several years, now they are so cheap there is no excuse:

 http://www.homedepot.com/p/Square-D-Home-Electronics-Protective-Device-HEPD-HEPD80/203540660

Very Cheap Insurance ^^^^^

And if you have some extra money for the home studio/stereo system:

Go Balanced Power: http://equitech.com/products/products.html