speaking of humming sounds...

[youra6]

Speaking of humming, my 10.2 hums a bit at random intervals. Sometimes it gets quiet, other times it gets quite audible. Hum gets louder when i crank up the volume knob. I bet its a ground loop issue but I havent been able to solve it. I've tried different cabling. I may have to test the receivers.

[Mike_TX]

Speaking of humming, my 10.2 hums a bit at random intervals. Sometimes it gets quiet, other times it gets quite audible. Hum gets louder when i crank up the volume knob. I bet its a ground loop issue but I havent been able to solve it. I've tried different cabling. I may have to test the receivers.

Someone should be able to suggest a ground loop FAQ.
That would actually be a good sticky thread under the "Audio Theory" forum.

Mike

[Ray3]

Mike - do you mean something like.....this:

My subwoofer has a hum, what do I do to fix the problem?
A subwoofer hum is a common problem. Unfortunately, there are numerous causes and the troubleshooting can be a bit tedious, but it is usually a problem that can be remedied at home. BTW – it is likely that the hum is also faintly audible in your speakers, but it is most evident in a subwoofer because it is a low frequency (around 60 Hz) buzz. OK, several things to consider, but generally, a hum is caused by having more than one device connected to a single ground and they use different paths to get to the ground, thereby creating noise (buzz/hum) in the system .

>Start with assuring that you are using a standard (audio) subwoofer cable, NOT a video cable.

>Did you do anything new/different just before the appearance of the hum? If so, disconnect or isolate what you did to see if that stops the hum.

>Try plugging the subwoofer power cord into the same circuit/power strip as the rest of your home theater system.

>Does the hum level change if you increase the volume of your receiver? If not, then the problem is happening somewhere after the receiver. So, does the hum occur regardless of your selected source (TV, CD player, PS3, DVD player, etc.)? If not, it’s probably a ground loop caused by adding an amplifier (sub).

>Disconnect the sub from the receiver and turn the sub on. If the sub still hums, you have a ground loop that is getting into your system from other equipment, your receiver, cable TV box (a major culprit), satellite receiver or other equipment in your system.

If the above “quick & dirties” didn’t eliminate the hum, we’ll take the next step. Since the vast majority of hum issues are caused by ground loop, let’s do some things to isolate the culprit. We can start by determining if it actually IS a ground loop with a simple test – using a “cheater” plug. Plug the three prong sub power cord into the two prong cheater plug (do NOT ground the grounding tab on the cheater plug). If the hum stops, it’s a ground loop. Because of safety considerations, do not use the cheater plug as the ongoing solution; it should only be used to test the system. It’s continued use is dangerous to both you and your equipment.



Now that we know it is a ground loop, let’s look at the top two contenders for being the culprit.

1) Cable TV or Satellite box. Disconnect the cable-TV feed (or satellite feed) from your cable box or satellite receiver (disconnect BEFORE before any splitters). If the hum/buzz stopped – done. If not, hook it all back up and move to step 2).

2) Subwoofer. Disconnect the cable that connects your subwoofer to the receiver. If the hum/buzz stopped – done. This is the culprit.

Solutions for 1) and 2):
· If it is the cable TV or satellite causing the issue, call the provider, tell them of the ground loop/hum issue and ask them to come and fix the issue.

· The satellite folks may also provide a fix. Note that a video ground isolating transformer will NOT work with a satellite setup, but a line-level audio isolator/transformer installed between the subwoofer and the receivers subwoofer connection should solve the problem. Again, if they can’t/won’t help, installing a line-level audio transformer yourself is a simple task.
· The cable company should either come out to 1) properly ground the cable TV circuit or 2) provide you with video ground-isolating transformer. The transformer is installed between the TV cable feed and the cable TV box. If they can’t or won’t help, you can obtain a video ground isolating transformer and install it yourself (an easy task).

There are many products out there that will solve the ground loop issue. Just do a search for “audio ground loop isolator” and find the one that works best for your system. Some examples.
Example 1 – the Radio Shack Ground Isolator (model # 270-054).


Example 2 - the Radio Shack Ground Isolator (model # GLI1-S1).


You may also need an RCA plug-to-plug coupler (model # 274-864) to connect the cable plug to the isolator plug. That is what causes the noise that is annoying you as a hum. Most of what we did above in the troubleshooting was to either isolate one of the multiple paths or get the paths unified to a single contact with the ground. Although some of the solutions involve outside parties (cable TV . satellite techs or electricians) the isolation transformer solutions are pretty much the quickest, easiest and most effective solutions and they don’t cost much. There is still a need to determine where the problem lies, but the fixes are pretty simple.


Example 3 – a simple, inexpensive in-line audio isolator - MCM Part #: 50-9041 (http://www.mcmelectronics.com/produc...-9041-/50-9041


Here are a few additional alternatives:
1) Try a power strip/bar that includes a coax (cable TV or satellite) in/out feature. BTW – don’t waste money on a “power conditioner” – they won’t help and your receiver already has filters in the mix.

2) If you are feeling adventurous, locate the cable connector box that feeds your house . It may already have a ground wire connected to it and to the electrical ground for your house. Clean the wire with sandpaper and re-connect.

3) If you have a turntable, try connecting a separate ground wire to a chassis screw on your receiver and see if the hum disappears. If you already have a turntable ground wire, try removing it from the receiver.

4) If the cheater plug and cable box/ satellite receiver exercise didn’t solve the problem, but the hum disappeared when you unhooked the sub from the receiver, it is likely the problem is being caused by something else in your system. Hook the sub back up to the receiver, then un-hook your other equipment (including the cable box / satellite receiver). Turn on the sub and see if the hum is gone. If so, begin adding back each of your devices. If one causes the hum to return, you have found the culprit.

The information provided here should eliminate the hum problem, but here are some links to several other resources on the subject.:

• http://www.psaudio.com/ps/how-to/finding-and-fixing-hum/
• http://www.siber-sonic.com/electronics/GLoopFix.html
• http://www.epanorama.net/documents/groundloop/index.html

• http://ezinearticles.com/?Eliminating-that-Terrible-Hum-From-Your-Home-Theater-Speakers&id=131193

[Mike_TX]

Yes.
You whipped that up quickly!
:)

Mike

[Ray3]

Actually, it's something I have been working on. :huge:

We plan to launch a FAQs section in the near future (no dates, no plans) and this will be part of it.

[youra6]

Thanks so much! I answered those questions below

Mike - do you mean something like.....this:

>Start with assuring that you are using a standard (audio) subwoofer cable, NOT a video cable. Yep bought one from monoprice.

>Did you do anything new/different just before the appearance of the hum? If so, disconnect or isolate what you did to see if that stops the hum.
If I disconnect RCA cable the sound goes away

>Try plugging the subwoofer power cord into the same circuit/power strip as the rest of your home theater system.
I did that.
>Does the hum level change if you increase the volume of your receiver? If not, then the problem is happening somewhere after the receiver. So, does the hum occur regardless of your selected source (TV, CD player, PS3, DVD player, etc.)? If not, it’s probably a ground loop caused by adding an amplifier (sub).
1. Hum gets louder when volume is increased on Receiver. I also get an audible static sound from the speakers past 70 on the receiver
2. It doesn't matter what the source is
>Disconnect the sub from the receiver and turn the sub on. If the sub still hums, you have a ground loop that is getting into your system from other equipment, your receiver, cable TV box (a major culprit), satellite receiver or other equipment in your system.
If I disconnect the sub from receiver the hum goes away.


If the above “quick & dirties” didn’t eliminate the hum, we’ll take the next step. Since the vast majority of hum issues are caused by ground loop, let’s do some things to isolate the culprit. We can start by determining if it actually IS a ground loop with a simple test – using a “cheater” plug. Plug the three prong sub power cord into the two prong cheater plug (do NOT ground the grounding tab on the cheater plug). If the hum stops, it’s a ground loop. Because of safety considerations, do not use the cheater plug as the ongoing solution; it should only be used to test the system. It’s continued use is dangerous to both you and your equipment.



Now that we know it is a ground loop, let’s look at the top two contenders for being the culprit.

1) Cable TV or Satellite box. Disconnect the cable-TV feed (or satellite feed) from your cable box or satellite receiver (disconnect BEFORE before any splitters). If the hum/buzz stopped – done. If not, hook it all back up and move to step 2).

2) Subwoofer. Disconnect the cable that connects your subwoofer to the receiver. If the hum/buzz stopped – done. This is the culprit.

Solutions for 1) and 2):
· If it is the cable TV or satellite causing the issue, call the provider, tell them of the ground loop/hum issue and ask them to come and fix the issue.

· The satellite folks may also provide a fix. Note that a video ground isolating transformer will NOT work with a satellite setup, but a line-level audio isolator/transformer installed between the subwoofer and the receivers subwoofer connection should solve the problem. Again, if they can’t/won’t help, installing a line-level audio transformer yourself is a simple task.
· The cable company should either come out to 1) properly ground the cable TV circuit or 2) provide you with video ground-isolating transformer. The transformer is installed between the TV cable feed and the cable TV box. If they can’t or won’t help, you can obtain a video ground isolating transformer and install it yourself (an easy task).

There are many products out there that will solve the ground loop issue. Just do a search for “audio ground loop isolator” and find the one that works best for your system. Some examples.
Example 1 – the Radio Shack Ground Isolator (model # 270-054).


Example 2 - the Radio Shack Ground Isolator (model # GLI1-S1).


You may also need an RCA plug-to-plug coupler (model # 274-864) to connect the cable plug to the isolator plug. That is what causes the noise that is annoying you as a hum. Most of what we did above in the troubleshooting was to either isolate one of the multiple paths or get the paths unified to a single contact with the ground. Although some of the solutions involve outside parties (cable TV . satellite techs or electricians) the isolation transformer solutions are pretty much the quickest, easiest and most effective solutions and they don’t cost much. There is still a need to determine where the problem lies, but the fixes are pretty simple.


Example 3 – a simple, inexpensive in-line audio isolator - MCM Part #: 50-9041 (http://www.mcmelectronics.com/produc...-9041-/50-9041


Here are a few additional alternatives:
1) Try a power strip/bar that includes a coax (cable TV or satellite) in/out feature. BTW – don’t waste money on a “power conditioner” – they won’t help and your receiver already has filters in the mix.

2) If you are feeling adventurous, locate the cable connector box that feeds your house . It may already have a ground wire connected to it and to the electrical ground for your house. Clean the wire with sandpaper and re-connect.

3) If you have a turntable, try connecting a separate ground wire to a chassis screw on your receiver and see if the hum disappears. If you already have a turntable ground wire, try removing it from the receiver.

4) If the cheater plug and cable box/ satellite receiver exercise didn’t solve the problem, but the hum disappeared when you unhooked the sub from the receiver, it is likely the problem is being caused by something else in your system. Hook the sub back up to the receiver, then un-hook your other equipment (including the cable box / satellite receiver). Turn on the sub and see if the hum is gone. If so, begin adding back each of your devices. If one causes the hum to return, you have found the culprit.

The information provided here should eliminate the hum problem, but here are some links to several other resources on the subject.:

• http://www.psaudio.com/ps/how-to/finding-and-fixing-hum/
• http://www.siber-sonic.com/electronics/GLoopFix.html
• http://www.epanorama.net/documents/groundloop/index.html

• http://ezinearticles.com/?Eliminating-that-Terrible-Hum-From-Your-Home-Theater-Speakers&id=131193

[tesseract]

I had a Cerwin Vega sub that had a really bad 60hz hum. It was unlistenable. I went to a hardware store, bought a 12ft. run of 18ga hook up wire and two spade connectors to crimp on each end.

I loosened a chassis screw on the sub plate amp, inserted one spade and tightened. I ran the other end to the ground post on the back of my FM tuner. No more hum!

[Travlinlght]

tesseract's solution has worked for me on more than one occasion....