Johnny dB Posted June 18, 2003 Share Posted June 18, 2003 So I rearranged my living room and when I plug in my HTR receiver i get a really annoying hum. It was so bad I thought the receiver was shot. I went to the local audio shop and they told me to unplug my cable. Huh, what would my cable have to do with it, I thought. So i go home, disconnect the cable going to the cable box and poof, the noise disappears. What the hell it works. I was told that all the rain that we got creates ground loop problems with the cable. Problem solved with a coax ground loop filter. $12.80 at parts express. Something to consider if you're getting some hum. Quote Link to comment Share on other sites More sharing options...
cyclonecj Posted June 18, 2003 Share Posted June 18, 2003 I had the same problem when I had cable. Grounding the cable block to my power center cured it. When I went to Satellite, I had the problem in the other room, since both sat receivers were hooked to the same dish, but were connected to opposite phases of the power line. I then had to run a ground from my sat dish to the power center. Quote Link to comment Share on other sites More sharing options...
justin_tx_16 Posted June 18, 2003 Share Posted June 18, 2003 problem would have also been solved with a ground cheater at about $0.35 though your solution is a better one, mine is just more economical. i have the same problem, most people do I think... hope selfishly hehe. Quote Link to comment Share on other sites More sharing options...
ShapeShifter Posted June 18, 2003 Share Posted June 18, 2003 Just be aware that the use of Cheater Plugs breaks the grounded connection! A properly grounded connection decreases the risk of a lethal shock. Because it allows the electrical circuit breaker or fuse to trip or blow. One will likely be ok unless something goes wrong inside the equipment or problems occur with an AC cord connected to the component. Remember Fire Marshall Bill!! Quote Link to comment Share on other sites More sharing options...
greg928gts Posted June 18, 2003 Share Posted June 18, 2003 When the electricity comes into your house, it is split from 240 volt to 120 volt at the panel, forming two different "sides" to the panel. You'll notice that the breakers are in two rows in the panel. What happens a lot of times, is that some outlets in a room are wired to breakers on one side of the panel, and others are wired to the other side. If you can get all the equipment onto circuits with breakers on the same side of the panel, ground loop and humming problems will most likely go away. If it's too difficult where the equipment is located to get everything plugged in to the same side of the panel, you can switch the breakers in the panel so they're on the same side. Greg Quote Link to comment Share on other sites More sharing options...
WMcD Posted June 18, 2003 Share Posted June 18, 2003 I have not had this problem with the cable coming in causing hum. But obviously it is a common problem. I can't quite agree with Greg that it is a function of ac feeds to the room being on different phases. But my knowledge is theoretical and I invite comment. Rather, it seems to me that the "ground" or shield connection of the cable is not at zero potental. Or, the ground wire on the service, connected to the chassis of the equipment is not actually at zero potential. It should be. As you might know, our audio interconnections work on the the difference in voltage between the signal and the "ground". (Balanced feeds are the exception.) The music signal is typically on the center pin of an RCA connector, and the ground reference is the sleeve (sp?). So, let's assume there is no music coming through on the hot pin. If the purported ground has a voltage on it (i.e. it is not at zero volts, being brought up to a level by a poor system) the amp still looks at this as a difference in voltage, and we hear the hum. One solution is to not connect the ground lead of the cable to your system. Isolation transformers can do that. The other solution is to tie the cable shield to your local ground. Gil Quote Link to comment Share on other sites More sharing options...
Johnny dB Posted June 19, 2003 Author Share Posted June 19, 2003 Greg is probably on to something. When I wired this into the box I put on the side with less fuses. I'll switch sides and see if it takes care of the problem. Quote Link to comment Share on other sites More sharing options...
Guest BobG Posted June 20, 2003 Share Posted June 20, 2003 If you measure potential voltage at the chassis of audio components, it will VERY rarely read 0 volts. Thus, current flows between components on the shield (common) side of the interconnects. With three wire interconnects ala pro world XLR, the signal and shield are separate. In consumer gear, with two conductor interconnects, all the noise flowing between "ground" planes on our components is mixed with the signal. Quote Link to comment Share on other sites More sharing options...
Johnny dB Posted June 20, 2003 Author Share Posted June 20, 2003 thanks Bob. I switched spots on my breaker box... no help. The coax isolator fixed the problem, though. Quote Link to comment Share on other sites More sharing options...
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