Spending hundreds (or even thousands) on new AV equipment only to discover annoying hums, clicks or hisses coming from the speakers can turn excitement into frustration in a hurry. While a malfunctioning component may be the cause, the problem more likely comes from the multitude of electronics in your home. Eliminating the problem may be as simple as changing outlets, or it may require more elaborate measures. Here’s a quick guide to troubleshooting, starting with the simplest first.

Ground Loops

Electronic cables are shielded to block electromagnetic radiation from both entering and leaving the cable. The shielding is usually connected to the electrical system ground circuit, which is common to the entire electrical network, unlike individual branch circuits. When electronic components are connected to outlets on different branch circuits, a single-loop antenna is created which can pick up all sorts of electronic noise and transmit it back to the components. This can cause humming or buzzing in speakers or create banding on video screens. It is the most common cause of interference and can be corrected by breaking the loop.

The easiest way to break the loop is by powering all the components from a single AC socket. By plugging into a single power strip, surge protector or power center, the ground paths return to a single point, preventing a loop from forming. With the low power consumption of most modern electronics, the load should be well within the 10-15-amp capacity of household branch circuits. If the problem persists, check your components to see if it any has its own independent ground wire and make sure it is properly connected.

If you can’t power all the components from the same outlet—self-powered remote speakers, for instance—a hum eliminator or ground loop isolator may be the solution. They’re simple devices that reprocess the electrical signal to break ground loops and other forms of interference. Models vary in their features, so shop around for one that does the job you need. 

Other Problems

Ground loops may be the most common source of trouble, but AC line noise, cable-to-cable induction, or radio-frequency (RF) interference can cause problems, too.

• AC line noise is caused by feedback from things like hair dryers, dimmers, blenders or worn-out fluorescent fixtures. You can identify it easily by simply turning those appliances or fixtures off and on to determine the source. An isolation transformer is one solution. Hospitals use them to protect sensitive instruments, and they work great for AV components, too.
  
  Inline uninterruptible power supplies (UPS) convert AC to DC and back again, so they eliminate interference. Good ones can be expensive, but they also have surge protection and battery backup, so they may be worth the cost.

• Routing power wires next to low-voltage AV cable can cause induction that creates problems. Signals from HDMI and USB cable shielding can also leak and cause static but it can usually be eliminated with a ferrite noise suppressor. Many have them built-in (they’re the cylindrical bulges at the end of the cable) or you can buy one to attach externally. Looping twin-lead antenna cables can create electromagnetic induction and interference, too.

• RF interference is everywhere. Cordless and cell phones emit it. So does wi-fi equipment. And computers do, too, even wireless mice and keyboards. That’s why computer cases and audio components have metal shells to block it. Most devices are designed to prevent it, but poorly made ones may not. Unfortunately, the only solution is to replace them with better-quality products.

If electronic interference is baffling you, or if you want to install trouble-free AV or electronic networks, the pros at Allstar Electrical Services can help. We can configure your home entertainment center, office, or any other room so there is enough convenient, stable, interference-free power to handle all the devices. We can help you power and locate routers or signal boosters so that your wireless devices work flawlessly. We can even bring more power to your home if it wasn’t wired to handle modern loads. In the hands of our experts, a home built 100 years ago can be wired and cabled safely for all your current and future needs.