So you just unboxed your new entertainment gear, hooked everything up, and you hear a buzz, whine, hiss, chatter, or any number of other annoying noises that have been known to plague audio equipment. You might even see some banding or waves on your TV. So you take it all back to the store, only to watch the salesperson plug it in and have everything work perfectly. What the…?
I’d love to tell you that you did nothing wrong, but you may have inadvertently. Then again, it could be bad wiring, defective equipment, or just a noisy electronic environment. Whatever the type of noise you’re hearing—and whatever the cause—here’s how to get rid of it.
The number-one cause of audio noise and weird video is the ground loop, simply because it’s so darned easy to create. The most common manifestations are a loud buzz or hum coming through the speakers, or scrolling bands on a TV screen. It could also be a much quieter, yet equally annoying buzz or hum that you only hear when the room is otherwise quiet.
A ground loop in entertainment equipment typically occurs when one or more pieces of equipment are plugged into the AC (alternating current) at different locations, then connected together by electrical (versus optical) signal cables—RCA, HDMI, composite, component—whose shielding is connected to ground. In the simplest terms, this creates a single-loop antenna that just loves to suck in various types of noise via electromagnetic induction. You can see how a loop is created in the diagram below.
One way to create a ground loop is to power inter-connected equipment from different AC outlets: The ground travels through the shielding of the signal cables(the red and gray lines in this illustration). (Click for larger image).
Anything that breaks the loop will remove the noise, and the easiest way to accomplish that is to power everything through a single AC socket. As shown below, simply plug all your equipment into a single power strip, surge protector, or power center and plug that device into the wall. Problem solved. Most multimedia setups can be handled easily by a single 10-amp circuit and most household circuits are at least that.
There might be occasions where you simply can’t reach the same outlet with a piece of equipment. Self-powered speakers and subwoofers come to mind. You could just “pull the ground” by using a three-prong to two-prong adapter but this represents a potential shock hazard. Look up Lee Harvey and Stone the Crows for an extreme example of what can happen with high-powered equipment.
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