July 08, 2010
| by CE Pro
Q. I recently purchased a pair of speakers that I use as my surround fronts, they sound great but sometimes I notice a static, fuzzy, cloudy, distortion sound. I tried 3 different receivers and still hear on occasion a fuzzy static sound, so I’m sure it is the speakers. I also moved the speakers away from my TV in case there was some signal problems, but no luck. What can be the problem? - Barry, Georgia
A. Bob Archer, Senior Editor, CE Pro, Dave Stevens of Steven’s Audio and Ric Johnson of Elite Systems Solutions weighed in via the CE Pro Forums.
Archer: Try the speakers and your A/V receiver/amplifier in another room. I suspect what you may be hearing is a ground loop and it could be caused by some other component within the room.
2. Try another set of cables. Cables that aren’t properly shielded can act like antennas for RF (radio frequency) and EMI (electro-magnetic interference) noise.
3. You can step up your power conditioning with a product that offers isolation, surge protection and power conditioning. Look at products from Torus, SurgeX, Richard Gray’s and Furman. Tripp Lite also offers basic isolation transformers (a device that will isolate the components plugged into from the rest of the products plugged into the same circuit). A power conditioner from a company like Torus will run anywhere from about $1,500 to a few thousand. A basic Tripp Lite isolation transformer can be found for less than $200.
Stevens: While I agree with Bob on all of the points he made, I would also take it a step further.
1. What is the brand of the speakers?
2. When you say “surround fronts,” are they your main front L/R speakers, or are they being used in addition to your front L/R mains for a “Height Channel” which some A/V receiver brands offer.
If they are your dedicated front L/R channels speakers in a 5.1 or 7.1 system, you more than likely have a defective driver in both. Most people believe that a speaker is blown when it no longer works. This is simply not true. A driver may be “stressed,” whereas it still works but will distort at a specific frequency and/or volume. Thus, the distortion you’re hearing is intermittent. Very common.
If they are additional “Height Channels” to your L/R mains, then there’s two ways to find out if it’s the speaker, ground loop, or the A/V receiver.
1. Connect the speakers by themselves into the main L/R outputs of your receiver. If they sound fine, then you know it’s not a problem with the speakers.
2. Take another pair of speakers, - for example, your existing rears - and hook them up to the same height channel outputs. Since you have no problem with your existing rear speakers, if they begin to distort on the same output, then you definitely have either an A/V receiver problem, or the other factors that Bob mentioned.
Johnson: I agree with Bob about the ground loop and with Dave about the testing. Since the static only is happening occasionally, what equipment is in use when this happens? Do you have a power conditioner in your rack and is it connected to a properly grounded electrical outlet?
Check the connections at the equipment end after you determine which pieces of equipment where in use that produced the static. Then make sure that the chassis earth ground wire is properly connected back to a good ground source.
Lastly, if the equipment connections look solid, do any of your wires run across an electric cord or wire, do any of them cross a metal duct, are any of them laying across any of the equipment? Another source of occasional static is harmonics that each piece of equipment sets up when operating. Properly dressing your cables away from electrical, mechanical interference may also help. Check each speaker cable for broken, cracked or damaged insulation.
Stevens: Adding to Ric’s post, (which I completely agree with), have you recently purchased a new refrigerator, wine cooler, or low voltage lighting that use dimmer switches? This goes to Ric’s post regarding a properly grounded and insulated AC outlet.
Anything with a compressor can wreak havoc with an A/V system every time the compressor turns on. Dimming switches on low voltage wiring systems also do the same thing, but you will hear the buzz become louder and softer as the switch is turned up or down.
I try to always play it safe and install a dedicated home run from the equipment to the main AC service panel.