Ground Loop


What is a ground loop? I understand that they can be caused by loose connections between components. What else can cause them? What are the effects? I have been told that humming from my power amplifier can be a symptom of a ground loop. True/False? Can ground loops cause damage to equpment?
mordenmail
Musicnoise: Please excuse the question but how do I connect the chasses together? Do I run the cable through the venting slots, tape the wire down to each component, use any method I can think of? When you say to run the wire to earth, what would be a good example of earth to connect to?
Mordenmail, you could use screws in the chassis connected to a spade. The best ground you would probably have is your wall plug ground. You could connect the final wire to the ground plug on a male ac plug. Neither the hot or the neutral should have any connection to them.

I suspect that you would have to lift the ac grounds of all of your ac cords or you would introduce a third path to ground and worse hum. I have never tried this solution.
in reponse to your question about connecting chasses - loosen a chassis screw on each item and connect via spade connectors. Earth ground would ideally be a ground rod - but the street side of the water pipe works fine or for that matter the electrical panel ground bus. The idea is to have only one path to ground. Make sure that all your chasses are connected to the ground pin of your ac socket (where your power cord plugs into the item). Cheat the ground pin on all power cords except one. That way you have one path to ground for all items. The only difference in resistance being the short high guage wire connecting the chassis - tighten the screws and this should be in the range of less than 50 milliohms. Just remember, if you later move your equipment around - uncheat the grounds. The only reason this is still safe is that you still have all chasses connected to ground via the interconnecting wires.
Note - by chassis I am referring to the metal case of each piece of equipment. Do not stick anything through the vents, to not connect anything to any component, do not insert anything into the interior of the equipment. Doing so is dangerous and will very likely end up with a "smokey" flavor to the music - i.e. you will fry the equipment. The connection I am referring to (to the chassis) is to a point on the case that you could touch by picking the unit up or moving it around - i.e. on the case.
TBG / Musicnoise,

Thank you for the remedial tutorial. It is appreciated. Thanks to Jea48 for the article.