Mike M Posted April 19, 2016 Share Posted April 19, 2016 My 115sw's occasionally do this same thing. Normally if I moved the subs out a foot or 2 and put them back it quits. It's picking up some type of interference from one of the multitude of electronics or led lighting I have in the room Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted April 19, 2016 Share Posted April 19, 2016 or led lighting These can be noisy I've noticed. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted April 19, 2016 Share Posted April 19, 2016 I found a little difference: no rca, minimum hum. WITH RCA (2 different cables) = hum One more test. Do this, except don't plug the RCA into the receiver, just the sub. Does it still happen? Just wondering if the RCA is working as an antenna. Quote Link to comment Share on other sites More sharing options...
Tobias Posted April 21, 2016 Author Share Posted April 21, 2016 I found a little difference: no rca, minimum hum. WITH RCA (2 different cables) = hum One more test. Do this, except don't plug the RCA into the receiver, just the sub. Does it still happen? Just wondering if the RCA is working as an antenna. yes, same noise! it's like an old refrigerator Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted April 21, 2016 Share Posted April 21, 2016 (edited) If that's the case you've got some kind of RF interference. Try to move the sub around and keep the gain low as a temporary band-aid until you figure out what is going on. If it were a ground loop, the noise wouldn't happen until you plugged in the RCA cable into the receiver. Edited April 21, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
jason str Posted April 21, 2016 Share Posted April 21, 2016 If that's the case you've got some kind of RF interference. Try to move the sub around and keep the gain low as a temporary band-aid until you figure out what is going on. If it were a ground loop, the noise wouldn't happen until you plugged in the RCA cable into the receiver. Most common but not always. Quote Link to comment Share on other sites More sharing options...
jason str Posted April 21, 2016 Share Posted April 21, 2016 Great article i found with other related links on this subject. >Here< Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted April 21, 2016 Share Posted April 21, 2016 (edited) Great article i found with other related links on this subject. >Here< "Ground loop is a condition where an unintended connection to ground is made through an interfering electrical conductor. Generally ground loop connection exists when an electrical system is connected through more than one way to the electrical ground." That's what's tripping me out though, there is no extra conductor, he isn't completing a circuit with the RCA cables, there is no "more than one way" going on. You've got two components plugged into the wall, that's it. If those two components were interconnected with an RCA cable then it hums, that's the definition of a ground loop, because the ground potential between the two is different, and the RCA cables are completing a circuit, making one component inadvertently ground itself through that cable. If plugging RCA cables in to the sub but not completing the circuit by plugging into the amp actually makes it worse, I would think that this either means you have a bad RCA cable, or that cable is acting as an antenna. I think he said he tried two different cables though. Edited April 21, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
jason str Posted April 21, 2016 Share Posted April 21, 2016 In this case it may not be in the audio system, i do not think the OP ever unplugged anything else for testing. Sure sounds like a ground issue. Your RF theory should be able to be tested by wrapping the sub in aluminum foil after you put electrical tape over the input or anything else that can short out by doing this. Quote Link to comment Share on other sites More sharing options...
jason str Posted April 21, 2016 Share Posted April 21, 2016 Personally what i would do to make this easy is take one of your subwoofers to a friend's house with a known good working subwoofer and replace it with your Klipsch subwoofer. If it hums there it is your amplifier that is faulty. No hum, you have a issue with your electrical. Quote Link to comment Share on other sites More sharing options...
jason str Posted April 22, 2016 Share Posted April 22, 2016 Were you planning on doing any more testing or just assume the amplifier is faulty ? Quote Link to comment Share on other sites More sharing options...
Tobias Posted April 22, 2016 Author Share Posted April 22, 2016 I put the antenna cable in another place, same problem, I don't know if it's in guarantee yet, I'll contact the seller. Thanks! Quote Link to comment Share on other sites More sharing options...
Tobias Posted April 22, 2016 Author Share Posted April 22, 2016 I found something: Noise reduced when Denon AVR-A100 is power off in stand-by mode. The Denon is 110v, with a "transformador" to 220v. Quote Link to comment Share on other sites More sharing options...
babadono Posted April 22, 2016 Share Posted April 22, 2016 got any dummys? Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted April 22, 2016 Share Posted April 22, 2016 I found something: Noise reduced when Denon AVR-A100 is power off in stand-by mode. The Denon is 110v, with a "transformador" to 220v. Maybe the receiver is dirtying up the power somehow? Do you have another receiver you could try? Quote Link to comment Share on other sites More sharing options...
Tobias Posted April 22, 2016 Author Share Posted April 22, 2016 got any dummys? I don't know what is that. I found something: Noise reduced when Denon AVR-A100 is power off in stand-by mode. The Denon is 110v, with a "transformador" to 220v. Maybe the receiver is dirtying up the power somehow? Do you have another receiver you could try? I don't have another receiver or amp (by now) Quote Link to comment Share on other sites More sharing options...
jason str Posted April 22, 2016 Share Posted April 22, 2016 If you disconnect the transformer does the hum go away ? Quote Link to comment Share on other sites More sharing options...
Tobias Posted April 22, 2016 Author Share Posted April 22, 2016 If you disconnect the transformer does the hum go away ? No, but the noise is less. Another weird thing is when I move the LFE knob, to then "non LFE positions", noise is reduced., almost to zero. Quote Link to comment Share on other sites More sharing options...
jason str Posted April 22, 2016 Share Posted April 22, 2016 With the RCA sub input cable unhooked ? Quote Link to comment Share on other sites More sharing options...
jason str Posted April 22, 2016 Share Posted April 22, 2016 Unplug the receiver and the RCA subwoofer input cable. Any hum at all ? Quote Link to comment Share on other sites More sharing options...
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