Ground loop in subwoofer -- did my printer create this?

[Woochifer]

Weirdest thing happened the other night. My subwoofer has an auto on, and when it kicked in, I got a loud humming sound. From the descriptions of ground loops I've read before, this seemed like one (high frequency buzzing along with a low frequency hum). The only change that I made that night was I plugged a computer printer to an adjacent wall outlet.

The way that my system is setup, all of the components in my audio rack go into a power strip with a line filter. I have both a cable TV and satellite input going into the VCR and satellite receiver. The subwoofer goes into a different outlet, but I believe that it's connected to the same circuit. That printer got connected to a wall outlet that I think is on a different circuit.

Turning the subwoofer off and on did not solve the problem. Unplugging both the subwoofer and printer, and only plugging back in the subwoofer did solve the problem. I never disconnected anything in the audio rack. Is it possible that the printer created a ground loop with the subwoofer?

When we had some work done to the house last year, the contractor noted that not all of the wall outlets were grounded and suggested that when we do any electrical work (which we will need when we install some new lighting), we should have all of the circuits in the house grounded to a single source. Would this prevent any future ground loops from forming?

[woodman]

My dear Wooch:

You (inadvertently) answered your own question! With all electronic troubleshooting, "clues" to the answer are gleaned by detective work which more often than not are the result of "what ifs?". In other words, what if I disconnect this - or, connect that in place of this? You say that when you disconnected the printer, the problem disappeared .... there is your answer. The printer was causing a "GROUND LOOP" with the subwoofer - plain and simple. Would that all troubleshooting was that easy!

Regards,

[Woochifer]

My dear Wooch:

You (inadvertently) answered your own question! With all electronic troubleshooting, "clues" to the answer are gleaned by detective work which more often than not are the result of "what ifs?". In other words, what if I disconnect this - or, connect that in place of this? You say that when you disconnected the printer, the problem disappeared .... there is your answer. The printer was causing a "GROUND LOOP" with the subwoofer - plain and simple. Would that all troubleshooting was that easy!

Regards,

Woody -

Well, maybe the simple answer really was the right answer. I guess I was looking for something more complicated. The idea of a dinky inkjet printer creating a ground loop seemed a little weird to me. I would've thought those were caused by components with transformers or big power supply components, or connections that can generate interference like cable TV or satellite inputs.

[Smokey]

When we had some work done to the house last year, the contractor noted that not all of the wall outlets were grounded and suggested that when we do any electrical work (which we will need when we install some new lighting), we should have all of the circuits in the house grounded to a single source. Would this prevent any future ground loops from forming?

No, that will not guaranty any future ground loops from forming. You still could get ground hum from ground difference on different circuits (fuse).

Woodman advice is good one and that is to use trial and error method. And sometimes I have found that cleaning connecters between components also help to alleviate ground hums.