![]() ![]() ![]() With the power OFF, reverse the AC plugs one by one of any other components that have a standard 2-prong AC plug that isn’t polarized.For safety, do not use a “cheater plug” to bypass the 3-wire plug. If it’s a 3-wire plug or a polarized plug, which has one prong wider than the other, you won’t be able to reverse the plug. Try reversing the AC plug for your A/V receiver or the powered subwoofer.Try plugging the subwoofer into a different AC outlet in the room, one that isn’t supplying power to your components (A/V receiver, TV, cable box, etc.).If you do not have easy access to the aforementioned ground isolators, here are a few more tips: In all cases, if your subwoofer has a ground-lift screw like some of Axiom’s subwoofers, try first removing the screw (or replacing it) to see if it increases or eliminates the hum. If a hum remains with the TV cable completely disconnected from your system, or you don’t want to risk degrading reception of HD signals from a cable or satellite system, then you may have to add a RCA ground isolator like these from Amazon or Crutchfield between the line-level coaxial subwoofer cable from your A/V receiver and the line-level input jack on your powered subwoofer. In many cases, the ground isolator will “break” the loop and remove the annoying hum or buzz by isolating the TV-cable ground. Install the ground isolator between the cable-TV feed and the input of your outboard cable-TV box or satellite tuner (or the TV display’s antenna or cable input if you have a set with a built-in TV tuner or a cable-card ready set). Note that these transformer-based ground isolators will work fine with analog cable-TV feeds, but depending on their design they may interfere with or block reception of HDTV signals via a digital cable or satellite dish feed. If that eliminates the hum, you can install an inexpensive in-line ground isolators like this from Amazon. Now see if the hum/buzz from your subwoofer stops. Be sure and disconnect the cable before any splitters. ![]() Reconnect your subwoofer’s coaxial cable from the subwoofer input to your receiver’s subwoofer output and disconnect the cable-TV feed (or satellite feed) from your outboard set-top cable box or satellite tuner.If it does, it’s likely coming in through your cable/satellite TV feed. First, the subwoofer: unplug the coaxial cable that connects to your powered subwoofer to see if the ground-loop hum disappears.If you get your system up and running and hear an audible buzz or hum, the first culprit to look at is either the powered subwoofer or your cable-TV or satellite-box feed at the entry point to your system.No further filtering is normally required.) Your receiver or amplifier already has a power supply with its own filters and transformers. Try these first and don’t waste money on a power “conditioner” which, in most cases, won’t help.(There is no need to “condition” the AC power for your system. Here are some methods to help you get rid of ground loops. The buzz/hum is a byproduct of the multiple power supply cables and a ground voltage differential within your system and its network of interconnecting cables. (All the grounds in an A/V system should ideally be at “0” potential.) A ground loop typically adds a loud low-frequency hum or buzz as soon as you plug in any of various audio or video components, including subwoofers, cable-TV outboard boxes, satellite-TV feeds, TV displays, amplifiers, A/V receivers or turntables. A “ground loop” is caused by the difference in electrical potential at different grounding points in an audio/video system. Of all the annoyances that can afflict any audio/video home theater or even a simple stereo installation, the notorious “ground loop” may well be the most difficult and persistent one to track down and eliminate. ![]()
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