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, at least 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.

Note: Some noise is inherent, such as tape hiss, or hiss when you turn up the gain on an input. It’s part of the equipment, and generally the only cure is… Better equipment.

Ground loops

The number-one cause of unusual 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 typically occurs when one or more pieces of your entertainment system 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.

Anything that breaks the loop will remove the noise, and the easiest way to do it 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  into the wall. Problem solved. Most multimedia setups can be handled easily by a single 15-amp circuit and most household circuits can deliver 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 Les Harvey and Stone the Crows for an extreme example of what can happen with high-powered equipment.

If using an extension cord is impractical, you can buy a hum eliminator, such as Ebtech’s Hum X. But that costs $70. There are other products that do roughly the same thing, some of which interrupt the loop in the signal cables, but they’re all expensive as well. If you have the skills, you can build your own hum eliminator for about $10 or $15. You’ll find plenty of information online that will show you how, but the task requires moderate skill with a soldering iron and similar tools.

If those methods don’t fix things, the problem could be an over-the-air (OTA) antenna or a cable-TV coax cable that has its own path to ground. I’ve received some pretty annoying shocks when handling coax signal splitters. Normally—because of the isolation built into cable modems, cable boxes, and similar equipment—this will occur only if you’re connecting directly to the TV or to a video recorder.

If you’ve traced the problem to the TV signal wire that’s attached to a cable modem or similar (disconnect it and see if the problem goes away) replace that piece of equipment—there’s something wrong with it. If you’re connecting directly to a TV, there are ground-loop isolators available for $20 to $30.

AC line noise

Ground loops are hardly the only thing that cause electrical noise; pretty much any device with a motor (hair dryers and blenders, for instance), as well as dimmer switches and failing fluorescent fixtures will create this type of interference. It might be audible through your audio equipment or visible on your TV, or it might not. The obvious solution for this type of noise is to not use those types of devices while you’re