Members mobobog Posted January 15, 2007 Members Share Posted January 15, 2007 I have just a couple pieces of gear, but i wondered... for those of you with lots of gear it would be impractical to have everything in the same mains... how do you avoid ground loops? Link to comment Share on other sites More sharing options...
Members NewYorkDave Posted January 15, 2007 Members Share Posted January 15, 2007 In small installation, lifting the shield at one end usually works. In large installations--or in any case where lifting the shield doesn't do the trick--there are always isolation transformers. One nice thing about old tube gear with transformer-coupled inputs and outputs is that the galvanic isolation was built-in and ground loops didn't occur as often. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted January 15, 2007 CMS Author Share Posted January 15, 2007 I have just a couple pieces of gear, but i wondered... for those of you with lots of gear it would be impractical to have everything in the same mains... how do you avoid ground loops?Connect shields on both ends. If you have a ground loop, fix the piece of equipment that's not properly grounded. Lifting shields is a halfway solution. It works until you put something new in the system that hums. Today it's easy to buy equipment that has balanced inputs and outputs so you can wire everything without having the cable shield carry a signal, but only serves as a sheild. If something hums, it's because ther's a grond problem within the piece of equipment itself. Sometimes it can be fixed, but better to replace it with a better designed piece. If you're connecting older of "semi pro" equipment you may have to deal with unblanced wiring. Take your chances. Link to comment Share on other sites More sharing options...
Members Lakesidedave Posted January 15, 2007 Members Share Posted January 15, 2007 I have a star ground system (separate ground from each of 12 outlets, connected to a half-inch copper rod buried 4 feet in the soil beneath the studio). No grounding problems at all, and there's a lot of gear. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted January 16, 2007 CMS Author Share Posted January 16, 2007 I have a star ground system (separate ground from each of 12 outlets, connected to a half-inch copper rod buried 4 feet in the soil beneath the studio).Depending on where that Bristol is, you may or may not have ground loop problems caused by the power line, and you may or may not have an electrical code violation and a potential power hazard. If there's a nearby lightning strike, there can be a substantial current through the earth, causing substantial current to flow between the power line neutral and your ground stake. That can overheat wiring and cause a fire. It's only legal in the US if the wire from your ground stake is bonded to the neutral at the point where power enters the building. Link to comment Share on other sites More sharing options...
Members philbo Posted January 16, 2007 Members Share Posted January 16, 2007 I don't normally do anything with ground loops. If I have a hum somewhere, I find out the problem and fix it.Generally it's not a problem. Link to comment Share on other sites More sharing options...
Members Lakesidedave Posted January 16, 2007 Members Share Posted January 16, 2007 Depending on where that Bristol is, you may or may not have ground loop problems caused by the power line, and you may or may not have an electrical code violation and a potential power hazard. If there's a nearby lightning strike, there can be a substantial current through the earth, causing substantial current to flow between the power line neutral and your ground stake. That can overheat wiring and cause a fire. It's only legal in the US if the wire from your ground stake is bonded to the neutral at the point where power enters the building. Bristol, England, United Kingdom. Passed and certified, installed by registered electrician. Been installed for 10 years. Thanks for your concern. Link to comment Share on other sites More sharing options...
Members where02190 Posted January 16, 2007 Members Share Posted January 16, 2007 Connect shields on both ends. If you have a ground loop, fix the piece of equipment that's not properly grounded. Lifting shields is a halfway solution. It's very common to connect the shield only on one end, and absolutely not necessary. A loop does NOT indicate a broken piece of gear, it indicates multiple paths to ground. The star ground system is what we employed here, and it works flawlessly. Funny I accidentally cranked the monitors up to full (had the dim switch, which is usually engaged, out) and still to my amazement, there is, with almost every pre and a ton of dynamics and fx patched and up, almost silence at full throttle. If possible, have a dedicated service installed for your studio. At minimum, get a real UPS(not the $50 Radio Shack ones). That one piece of gear for us (an APC unit, highly recommended) made a massive difference. The noise level, which was pretty acceptable prior, went to basically nothing. I never have to worry about anything that anyone wants to interface. I never, ever have noise or ground loop issues. Good cabling, and routing of same is also key. Keeping any audio far away from AC and any wall warts, and if you must cross paths, do so at right angles. Link to comment Share on other sites More sharing options...
CMS Author MikeRivers Posted January 16, 2007 CMS Author Share Posted January 16, 2007 Bristol, England, United Kingdom. Passed and certified, installed by registered electrician. Been installed for 10 years. Thanks for your concern.Over there, they don't tie one side of the power line to ground, so any "ground loops" that you have, if you want to do the job right, need to be fixed within the guilty piece of equipment. (which is of course always the right thing to do) Link to comment Share on other sites More sharing options...
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