Very Strange Sub distortion - help!

[traveler138]

I am perplexed and am hoping that someone might be able to help out.

I am getting random distortion coming through my powered sub woofer(s). I originally thought this had to do with my amp, interconnects or line conditioner but have eliminated all those by testing several combination.
I am able to reproduce this on two different powered sub woofers and two different amps and with several different interconnects combination s (XLR. etc) .

I get this noise on both subs (different brands) and when they are plugged in to a line conditioner or directly into the AC outlet - including with nothing else connected to the sub (no interconnects). This tells me its not amp, component or interconnect related.

I can reproduce it on both amps in different AC outlets including a brand new dedicated AC outlet - one that is independent of all other in the home.

Here is the real kicker. I have experienced this problem in TWO different homes in different areas. In the first home I thought I was due to a ground loop. Then I moved. I had an electrician come out and check the wiring in the second home to verify that I do not have ground loop issues. Same issue on both subs in both homes....

The sound/distortion is nearly always the same. It is not a consistent hum or high level popping but more of a low level garble, generally starting out slow then at times building in intensity and volume. It is random. It can be very low level, then can build in volume. Almost sounds like something is loading up. When I turn the power off of the sub it goes away. The sound is basically the same on both amps and will be produced either connected to the amps, plugged into APC line conditioner with no interconnects, or straight into the wall (directly or using an extension cord, either way, same issue).

One of my subs is a Sunfire Tru-EQ. I called support to see if they might have any ideas. They thought a Audio Insulation Transformer might be something to try but from what I am reading these seem to address ground loops. Any thoughts on these?

I would assume my APC line conditioner with battery backup would regulate power well enough to address AC power issues and I dont think this is a ground loop issue because it is not a hum.

I have purchased a Entech HumX - with no success.

I have disconnected my Comcast cable thinking this might be causing an issue. No difference.

Can this be some kind of radio frequency interruption? Can this be caused from the home wireless network?

I am at a loss.

Any ideas on what it might be, what to test next, how to make it go away?

Thanks
Kevin

 

[TLS Guy]

I am perplexed and am hoping that someone might be able to help out.

I am getting random distortion coming through my powered sub woofer(s). I originally thought this had to do with my amp, interconnects or line conditioner but have eliminated all those by testing several combination.
I am able to reproduce this on two different powered sub woofers and two different amps and with several different interconnects combination s (XLR. etc) .

I get this noise on both subs (different brands) and when they are plugged in to a line conditioner or directly into the AC outlet - including with nothing else connected to the sub (no interconnects). This tells me its not amp, component or interconnect related.

I can reproduce it on both amps in different AC outlets including a brand new dedicated AC outlet - one that is independent of all other in the home.

Here is the real kicker. I have experienced this problem in TWO different homes in different areas. In the first home I thought I was due to a ground loop. Then I moved. I had an electrician come out and check the wiring in the second home to verify that I do not have ground loop issues. Same issue on both subs in both homes....

The sound/distortion is nearly always the same. It is not a consistent hum or high level popping but more of a low level garble, generally starting out slow then at times building in intensity and volume. It is random. It can be very low level, then can build in volume. Almost sounds like something is loading up. When I turn the power off of the sub it goes away. The sound is basically the same on both amps and will be produced either connected to the amps, plugged into APC line conditioner with no interconnects, or straight into the wall (directly or using an extension cord, either way, same issue).

One of my subs is a Sunfire Tru-EQ. I called support to see if they might have any ideas. They thought a Audio Insulation Transformer might be something to try but from what I am reading these seem to address ground loops. Any thoughts on these?

I would assume my APC line conditioner with battery backup would regulate power well enough to address AC power issues and I dont think this is a ground loop issue because it is not a hum.

I have purchased a Entech HumX - with no success.

I have disconnected my Comcast cable thinking this might be causing an issue. No difference.

Can this be some kind of radio frequency interruption? Can this be caused from the home wireless network?

I am at a loss.

Any ideas on what it might be, what to test next, how to make it go away?

Thanks
Kevin

If I understand this right, then you get this noise, (it is not distortion) if your subs are not connected to anything, just plugged in. So this eliminates a ground loop.

You mention one sub brand, what is the other? If they are the same, this is almost certainly a design fault.

You say you have moved homes, how far?

If two subs of different manufacturers are doing the same thing in two very different locations with no input connection, then logic would dictate only one explanation. That would be radio frequency penetration from emissions from some electrical device you own, that moved with you.

 

[traveler138]

Thanks for the response.
Yes the subs are different brands (one is Sunfire, the other a cheap JVC).
The move was about 5 - 7 miles as the crow flies.
Any ideas about what can cause this kind of issue? How to isolate it?

 

[TLS Guy]

Thanks for the response.
Yes the subs are different brands (one is Sunfire, the other a cheap JVC).
The move was about 5 - 7 miles as the crow flies.
Any ideas about what can cause this kind of issue? How to isolate it?

5 to 7 miles is not far. So there could be piece of equipment in that region, probably industrial related, that is sending interference back down the AC wires, and getting distributed by the power company.

The other issue is RF from some piece of electronics, like a fridge, deep freeze, or convection oven that moved with you.

What devices that contain motors moved with you? Switch them off one by one by one and see if you can find the culprit.

If it is mains introduced you likely won't nail that without instruments like scopes. You can contact the power company, but they are usually very unhelpful with these kinds of issues.

You could try putting RF chokes in the mains lead to the subs, and see if that helps. If not the only thing you can do is buy a high grade sub that does not have a switching power supply. Switching power supplies are notorious for transmitting mains interference. Those power supplies are widely used to power the class D amps, that so often power subs.

We seem to get more darn sub issues than any others. I'm rapidly coming to the conclusion that most subs are poorly designed and built and are just trouble.

The case for building your own with a decent amp is getting stronger and stronger. Many on these forums do and I think that was time and money well spent.

I don't own a commercial sub and never will. I'm glad I don't have to tangle with those troublesome units.

 

[tcarcio]

I had the same type of problem when I was in my last home ans after going nuts trying to fix what I thought was something I had it turned out to be a transformer on the pole outside my house. After I was there about 2 years they changed it for some other reason that I don't know and the noise was gone. You might have the same type of issue.

 

[TriMe]

cable in the area...

this is true, most likely the hum is always there not just audible to the ear...do you have cable? Cable is almost always the culprit in my experience.

 

[TLS Guy]

this is true, most likely the hum is always there not just audible to the ear...do you have cable? Cable is almost always the culprit in my experience.

Read the OP's post properly, it is not the cables!