The classic ground loop is shown in the graphic below. You can see that the green shaded area is the area that gets cut by any stray mag field (whether internal to the equipment or external). The best defense is to minimize the loop areas, and in really stubborn cases, you can use a ground lifter, although I have managed in the last few yrs to build gear that does not require it. With this kind of problem, you really have to keep the ground loop currents out of the signal return - any voltage appearing across the signal return is effectively in series with the source signal.
note that the cross section area in a typical interconnect is very small, so this is not usually how the noise is picked up.
Here is a really excellent set of posts by diyAudio member ilizmn that I collected into a single document.
Ilizmn’s excellent posts on ground loops
note that the cross section area in a typical interconnect is very small, so this is not usually how the noise is picked up.
Here is a really excellent set of posts by diyAudio member ilizmn that I collected into a single document.
Ilizmn’s excellent posts on ground loops
