More on Power Mac G4 Ground Loop Buzzing Problems

Adrian Fry has submitted a few ideas for isolating and elimination of the previously reported and detailed ground loop problems that cause audio buzzing and humming noises in various Power Mac G4 models:

"1. Do not 'lift' the ground from a piece of equipment - this can be fatal if a fault occurs.

2. As you previous contributor noted, connect the computer and audio gear to the same wall socket, even if this means making up some long mains cables specially.

3. If the hum persists, try going around the house unplugging other electrical equipment in turn - you may find the source to be something like a fridge ! If it is, check it's mains socket to ensure the earth is properly connected.

4. If it persists, forget ground loop isolators - go buy a DI (Direct Injection) box from any pro-audio dealer - DI boxes have a switch labeled 'Ground Lift' for solving this type of problem. The ground lift switch will lift the ground (safely) and the hum should stop!

"And make sure you audio and video leads aren't running over/under any mains leads - the Mac's output unbalanced audio easily picks up stray electrical fields."