Possible power issue...thumping in subwoofer

[karups2]

I have a Velodyne 1012X that occasionally (once/day or less) will start making thumps and then stop thumping on its own. Could this be a power conditioning issue? The subwoofer cable is a Monster cable so I think it should be reasonably well shielded.

These thumps happen even when I'm not playing anything (volume turned to zero; and, indeed, I think even when the main amplifier is off, although the subwoofer's internal amplifier is still on).

I saw the article on ground loops, but there is no buzz.

A former housemate of mine bought a really nice stereo set-up and shortly after buying it noticed problems when the bathroom light was turned on (he took it back to the shop and they installed some power-related thing). So maybe the electrical system in the house is pre-disposed to problems.

Anyway, I want to fix it as cheaply as possible. I'm wondering if the following thing will do the trick:
PureAV AP11000fc-10 10-Outlet PureAV Home Theater Power Conditioner (for $45 on Buy.com)

 

[TLS Guy]

I have a Velodyne 1012X that occasionally (once/day or less) will start making thumps and then stop thumping on its own. Could this be a power conditioning issue? The subwoofer cable is a Monster cable so I think it should be reasonably well shielded.

These thumps happen even when I'm not playing anything (volume turned to zero; and, indeed, I think even when the main amplifier is off, although the subwoofer's internal amplifier is still on).

I saw the article on ground loops, but there is no buzz.

A former housemate of mine bought a really nice stereo set-up and shortly after buying it noticed problems when the bathroom light was turned on (he took it back to the shop and they installed some power-related thing). So maybe the electrical system in the house is pre-disposed to problems.

Anyway, I want to fix it as cheaply as possible. I'm wondering if the following thing will do the trick:
PureAV AP11000fc-10 10-Outlet PureAV Home Theater Power Conditioner (for $45 on Buy.com)

You can't spend money after guessing at the problem. I think you have a faulty piece of equipment delivering spikes to the loudspeaker driver. Now this could be a defect in the unit to which it is connected, or the amp in the sub. Disconnect the sub from your receiver or what ever is powering it. Leave it on and see if the thumps still occur. If they do you sub is faulty and most likely has a bad cap. If the sub is silent, and the thumps return after reconnection, then it is the sending device.

My hunch is it is he sub as you think it still occurs with the main amps off. You really have given little information on your set up, as is usual. Trouble shooting at long range is very difficult, and without ALL the details likely to lead to some wrong conclusions. My strong sense is though, that your Velodyne sub needs service.

 

[karups2]

You can't spend money after guessing at the problem. I think you have a faulty piece of equipment delivering spikes to the loudspeaker driver. Now this could be a defect in the unit to which it is connected, or the amp in the sub. Disconnect the sub from your receiver or what ever is powering it. Leave it on and see if the thumps still occur. If they do you sub is faulty and most likely has a bad cap. If the sub is silent, and the thumps return after reconnection, then it is the sending device.

My hunch is it is he sub as you think it still occurs with the main amps off. You really have given little information on your set up, as is usual. Trouble shooting at long range is very difficult, and without ALL the details likely to lead to some wrong conclusions. My strong sense is though, that your Velodyne sub needs service.

Thanks for the reply; I'll try disconnecting the sub and see if it still makes noise. Any guess on what it might cost to fix that? Might be cheaper to get another sub.

I'm happy to provide additional details, although I don't know what details might be pertinent. The setup is a Pioneer VSX-D509S powering Polk bookshelf speakers at left/right and Cambridge Soundworks center, rear-left, rear-right and Velodyne 1012X sub. It is all crammed in a small area with cables going everywhere.

The noise is not isolated to any particular source equipment. There seems to be no rhyme or reason to when the the thumps happen. They usually last 2-3 seconds or so and happen at a frequency of less than once/day (as far as I can tell...I'm rarely home all day). The house is circa 1915, although I think the circuit the stereo is on was installed by a non-licensed electrician in the 1950s. I plugged a surge protector into a different outlet on the same circuit and a red light went on warning of some problem with the ground (it works fine, although perhaps it is less safe...I'm just renting so it's not something fixable)

 

[TLS Guy]

Thanks for the reply; I'll try disconnecting the sub and see if it still makes noise. Any guess on what it might cost to fix that? Might be cheaper to get another sub.

I'm happy to provide additional details, although I don't know what details might be pertinent. The setup is a Pioneer VSX-D509S powering Polk bookshelf speakers at left/right and Cambridge Soundworks center, rear-left, rear-right and Velodyne 1012X sub. It is all crammed in a small area with cables going everywhere.

The noise is not isolated to any particular source equipment. There seems to be no rhyme or reason to when the the thumps happen. They usually last 2-3 seconds or so and happen at a frequency of less than once/day (as far as I can tell...I'm rarely home all day). The house is circa 1915, although I think the circuit the stereo is on was installed by a non-licensed electrician in the 1950s. I plugged a surge protector into a different outlet on the same circuit and a red light went on warning of some problem with the ground (it works fine, although perhaps it is less safe...I'm just renting so it's not something fixable)

That is useful information. Whether you rent or not, the power situation has to be investigated. It may not be a grounding problem, it may be worse a neutral problem.

Get a multimeter if you don't have one. On each electric outlet there are three prongs. The round center is ground. There is a smaller slot, the live and a slightly larger slot, the neutral. Between the live and neutral there is 120 volts AC. Between live and ground there should be 120 volts AC. Between neutral and ground there should be 0 to 0.5 volts, at the very most I volt. Problems are reversal of live and neutral and even more common errors in neutral wiring causing neutral overload. This is often referred to as neutral gouging. This is dangerous. I recently came across a case where the neutral burnt right off the panel.

Now neutral problems are a potent cause of building fires. Check this out and if the landlord won't fix it, find somewhere else to live fast! You won't cure this with any surge protector or power conditioner. Only a double conversion UPS would protect equipment from a problem like this. They are expensive and won't stop the building burning down. That warning on the surge protector needs tracking down pronto.