The dilemma is that solving noise problems is an art within itself. Since it does not come up every day, we all have limited practical experience. This has spawned an industry for those who are now specialize in solving noise problems.
A good power distribution system is essential for proper operation of audio system. Professional audio systems just doesn’t work well with normal extension cords running hundreds of feet to a stage. Besides the power feed the good grounding of the whole system is essential.
Ground loop is a condition where an unintended connection to ground is made through an interfering electrical conductor. Generally ground loop connection exists when an electrical system is connected through more than one way to the electrical ground.
When two or more devices are connected to a common ground through different paths, a ground loop occurs. Currents flow through these multiple paths and develop voltages which can cause damage, noise or 50Hz/60Hz hum in audio or video equipment. To prevent ground loops, all signal grounds need to go to one common point and when two grounding points cannot be avoided, one side must isolate the signal and grounds from the other.
The bottom line is that a perfect “quiet” ground does not exist. The basics of all noise problems on the grounding system boils down to what is objectionable current. With the exception of hospital systems, the definition is vague at best. The standard electrical grounding system throughout the building isn’t designed to have current constantly flowing through it–and yet it does, you cannot stop it. The reason a ground will not and never be perfectly noise free is that the grounding electrode conductor is nothing more than a long wire from point A to point B. And the longer the wire the more noise it will pick up.
Sound and video people are referring to the type of noisy ground with term like ground loops: current running the equipment grounding conductor, metal within the building, and grounding electrode conductor. Use of any of today’s standard 120-volt or 230-volt single-phase AC systems mean potential problems for audio equipment. Computer guys have the same problem in their line of work and so forth.
Usually ground loops are an after-the-fact type of problem in which the end-user blames the installer, the installer blames the manufacturer, and actually nobody is at fault. Neither the manufacturer nor the installer can usually predict where a loop will occur. Only after the system is installed can it be determined if a problem will exist.
Ground loop problems can be corrected and avoided. It is important for the dealer, isntallee and the end user to be aware that this problem can occur. It is a good idea to design the system to avoid most obvious source of this kind of problems, and then be prepared still to face some problems when starting to use the system. A ground loop problem may occur at several points in the system, and each occurrence of the problem must be corrected individually.
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