highnote Posted October 15, 2001 Share Posted October 15, 2001 I have a Klipsch Sub connected to my Yamaha Home Theater Receiver. I have a ground loop problem between the two. If I plug the Sub into the same outlet as the Yamaha, No Hum. If I plug the sub in across the room (which is where I want it!), moderate hum. I found I could eliminate the hum by cutting the ground wire out of the power cord on the Klipsch Sub. Works like a charm. Question(s) is(are): what risks am I running by using the Klipsch sub ungrounded, and what other noise reduction approaches could I use if the risks of this approach are deemed unacceptable? Thanks for your help!! Quote Link to comment Share on other sites More sharing options...
dougdrake2 Posted October 15, 2001 Share Posted October 15, 2001 HN - While lifting the ground (using a 3-2 prong cheater plug) is a common remedy for ground hums, my recent adventures in this arena turned up quite a bit of disapproval of this process by manufacturers of the equipment in question. The piece is designed to use that 3rd prong for ground, rather than the design that only uses 2 prongs, so you are potentially creating a shock hazard if you bypass the 3rd prong. I'd suggest taking the "simple" way, if possible, and that is running an extension cord of adequate capacity so that both units are plugged in to the same outlet. Others may know of a simple wiring trick that could fix this (like reversing the hot/cold leads in the outlet -- don't know if that fixes it, that's just an example of the kind of trick I am referring to). Otherwise, start disconnecting devices to see what makes the hum go away. A common culprit is a cable TV lead, but it might be another "upstream" source device. Good luck, and keep smiling! DD2 Quote Link to comment Share on other sites More sharing options...
RossVTaylor Posted October 15, 2001 Share Posted October 15, 2001 Hi Highnote, If Doug Drake's extension cord advice solves your problem, then that means your ground hum issue should be pretty easy to solve permanently. It's likely that the other receptacle you're using across the room is on a different leg of the power drop to your house. It's fairly easy to switch this, if that's the source of the problem. First, identify the breakers that control the circuit your other equipment is on and the circuit that you want to use for the subwoofer. I'm assuming they're on different circuits, otherwise that's not the source of your trouble. Where are the breakers in relation to each other in the circuit panel? If they are directly next to each other (one on top of the other), then they are most likely on different legs. Each of the 110V legs coming into the box is run to a buss bar - the buss bars usually run from top to bottom on either side of the box. Although it would seem that all the left-side breakers were on one leg and the right-side breakers were on the other, this is usually not the case. In most residential panels, the buss bars have "teeth" and the result is that adjacent breakers (one over another) are on opposite legs of the service. Whew... talk about long winded. Now, where was I? Oh, yeah... if the two circuits you wish to use are on different legs, you can swap breakers (or the wires to breakers) and move them around so they're on the same leg. Just, PLEASE, make sure the incoming power is OFF! Try out the extension cord fix and, if that works, take a look at the breakers. Plug lamps into the receptacles and turn off breakers until you find the right ones. Once you've identified the location of the breakers, report back to us and we can guide you further. Ross ------------------ "Time flies like an arrow. Fruit flies like a banana." Quote Link to comment Share on other sites More sharing options...
jjhaz@ont.com Posted October 15, 2001 Share Posted October 15, 2001 My Klipsch sub came with a ground lift adaptor from Klipsch. I wouldn't worry about using one. Good luck, Jeff ------------------ Cornwalls Main fronts KLF-C7 Center IW-150 Rears KSW-12 200watt Sub Anthem AVM20 Preamp 5 Adcom 555s all mono BLK Toshiba 9200 DVD Sat. / Mit. VCR ----------------------- Project room Genelec Nearfield Monitors with Genalac Sub Alisis 32 channel board Joe Meek VC1Q Studio channel Art Power Plant Roland R8 Wave/24 24bit recording Aphex Comperesors And so on. Quote Link to comment Share on other sites More sharing options...
highnote Posted October 17, 2001 Author Share Posted October 17, 2001 Thanks for the replies. I thought that I had checked the electrical connections as thoroughly as possible, but I was wrong again. I did have the two circuits on separate legs of the 220 main coming into the house. Doh! Once switched, the hum went away. I still wonder about the ground,though. Where does the shock hazard exist in that subwoofer? Seems pretty well insulated/isolated in my opinion. Any weigh-in from Klipsch personnel on this? Is a ground really necessary? Thanks again! Quote Link to comment Share on other sites More sharing options...
boa12 Posted October 17, 2001 Share Posted October 17, 2001 high, the manual for my velodyne sub also says it's fine to use a 3/2 lifter which I do to remove any potential ground noise. the safety hazard i would think comes more into play for devices with metal casing like a power amp. though a sub does usually have a metal plate on the back. so if u lift the safety ground be careful there. Quote Link to comment Share on other sites More sharing options...
SickPuppy Posted October 18, 2001 Share Posted October 18, 2001 But ya see, In my opinion, Klipsch planned ahead for a problem that isnt their fault! If they put a three prong plug on it, then you have a choice to cut off the ground leg or use a 3/2 adapter. However, if they just put on a regular 2 prong plug, it has to be one of the polarized type with the larger prong for the groung or neutral and internally connect the groung to the nuetral leg. If this were the case and you got a ground loop issue, you cant cut the ground out of the loop with out taking your sub apart to internally remove the ground....what a pain! so they did us a favor by wiring with a 3 pronger! Quote Link to comment Share on other sites More sharing options...
avman Posted October 21, 2001 Share Posted October 21, 2001 yeah boa, i got 'bit' well-more like 'nibbled' by a metal back-plate on a klipsch sub when i lifted the ground. other than that, problem solved.avman. ------------------ 1-pair klf 30's c-7 center ksps-6 surrounds sony strda-777ES receiver upgraded to v.2.02 including virtual matrix 6.1 sony playstation 2 dishnetwork model 7200 dishplayer satellite receiver/digital bitstream recorder pioneer dvd player sharp 35"tv panamax max dbs+5 surge protector/power conditioner monster cable interconnects/12 gua.speaker wire a 'teens' sub coming!(RSW-15 LOOKIN'GOOD!) KLIPSCH-So Good It Hz! Quote Link to comment Share on other sites More sharing options...
martindemon Posted October 22, 2001 Share Posted October 22, 2001 Another case of harmonic pollution on the power network. That can be a sign of one or several of these problems : 1) The Yamaha receiver adds a lot of current harmonics (power frequencies of an integer multiple of the fundamental ; 60Hz) ; lack of filtering on the Yam? 2) The Klipsch sub is sensitive to harmonics in the power network or it's amp is badly shielded ?? (i Really hope not because i plan buying a KSW12 soon...) 3) There was something plugged near the power line of your sub that was generating the noise (harmonics) ; refrigerator? 4) What cables are you using? are they long? what gauge? are they shielded? When you had the noise, did your cables passed near some power cords (your Yamaha's perhaps?) ------------------ If it's not broken, don't fix it. This message has been edited by martindemon on 10-22-2001 at 09:05 PM Quote Link to comment Share on other sites More sharing options...
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