How to Eliminate Hum or Buzz
 by Alan Lofft, (bio), Axiom Audio The Ground Rules 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. A "ground loop" is caused by the difference in electrical potential at different grounding points in an audio/video system. (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. 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. Here are some methods to help you get rid of ground loops. 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. Your receiver or amplifier already has a power supply with its own filters and transformers. No further filtering is normally required.)
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). In many cases, the ground isolator will "break" the loop and remove the annoying hum or buzz by isolating the TV-cable ground. 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 ground isolator like this Radio Shack Model 270-054 between the line-level coaxial subwoofer cable from your A/V receiver and the line-level input jack on your powered subwoofer. 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. It may or may not make a difference. If you do not have easy access to the aforementioned ground isolators, here are a few more tips:
Finally, here is another solution that worked well for a member of our message boards who decided to discard his ground-loop isolator on his subwoofer: "I took off the ground-loop isolator I'd been using and connected a plain 14-gauge wire to chassis screws on the sub and the receiver then powered everything on. Although hum was still there, it was far lower than before. Next I unscrewed the ground-loop screw on the back of the sub and that took care of the hum completely."  |
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     New member Username: Derekl00Boston, MA USA Post Number: 1 Registered: Dec-05 |
I've got a somewhat different problem. I occassionally get little burps or growls (more or less just random low frequency noise) out of my subwoofer. After careful observation I've noticed that it only occurs when my furnace is on and running hard. Any suggestsion for how to eliminate this other than turning off the heat and possibly freezing to death? |
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New member Username: All_wired_upPost Number: 2 Registered: Dec-05 |
Move your Sub to a different power outlet. |
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New member Username: Rohit1712Hyderabad, AP India Post Number: 1 Registered: Mar-06 |
I am using a Denon DVD Player 2910, Jamo SUB, Rotel Processor 1068, sony projection tv. I keep getting frequent shocks when I touch the surface of either the DVD Player or the Rotel Processor, Sometimes their severity is high and sometimes mild to "Not present". Another problem that is noticable is that my Rotel 1068 processor's On screen Display(OSD) when output to the sony projection tv vibrates severely.Recently my rotels power board blacked out. After getting it repaired I am very concerned what could have caused it ( I am using a cheap AVR). What could I do to remove the vibrations in the OSD of my rotel processor? What about the shocks could there be any ground loop problem in my setup? |
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New member Username: ChardPost Number: 1 Registered: Mar-06 |
Hi, I need some help with a very audible hum from my studio monitor speakers...here are the details: I just moved into a 50 year old house with a few ungrounded circuits. Of course, the one I use for my Computer/audio server system is one of these ungrounded circuits. I have everything plugged into a Belkin 1500 UPS, and I have jumped the neutral to ground on the receptacle. Everything works fine except that I am getting a very audible hum from my powered studio monitor speakers (Event 20/20p). They are connected to the computer via the line out/headphone 1/8 inch jack on my Soundblaster Audigy 2 Platinum EX card. The hum gets noticably louder when the computer boots up, but its always there to some extent....I am really frustrated at this point, and need some advice on how to attack this problem... Thanks in advance |
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New member Username: CestoBrunswick, ME United States Post Number: 1 Registered: Mar-06 |
David N Heffner, Have you found a solution? i have the same problem but only i have a pair of KRK RP8 moitors, and the hum is quite disturbing. It sounds like i can hear the computer processing, cause when i move my mouse and when ever i open a program or am just idleing i her a stiff buzzing, not that loud but definitly noticable. ECOUSTICS HELPPPPP!!!! |
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New member Username: ChardPost Number: 5 Registered: Mar-06 |
Shawn, I did indeed find a solution. I bought a Ground Loop Isolator ($20.00 at Best Buy -- go to the car audio department) and plugged it inline between the computer and the speakers. This solved the problem 95% of the way. I am not familiar with your speakers...but mine are studio monitors which are not necessarily intended to be used in such close proximity to a CPU. That's why I always get a tiny bit of hum. The GLI returned my system to this state...so it should probably return yours to your normal state (assuming all other variables remain the same!). Any other questions, let me know...hope it works for you. |
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New member Username: FranPost Number: 1 Registered: Apr-06 |
Turntable Cartridge Strangeness... Dear eCoustics Experts, Can you solve my unusual turntable hum problem? I use a Pioneer PL-512 stereo turntable with a Pioneer M75ED Type 2 cartridge. The turntable has no hum because (so far as I know) it is correctly earthed to its accompanying amp. However... as soon as I put the cartridge down on a turning LP, a deep hum starts through my speakers, as the music plays. The hum is dependent on the cartridge being down on the record's surface. So far as I know, the cartridge is correctly wired. What should I do? With many thanks for any advice which you might be able to offer. Francois. |
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New member Username: MgmeadPost Number: 1 Registered: Apr-06 |
I have a bit of a different problem -- it's possibly related. I'm in a "mixed ground" house (part is grounded, part is not, part is as old as knob and tube!). I've plugged some things into the house -- lights, TV, computer laptops, a printer, a few nightlights. What I'm getting isn't a straight out hum ... it's a barely audible (to me and the dogs in the neighborhood probably) HIGH pitched whistle. Ever heard of something like this? It's making me a little special in the head and I'm just afraid to bring my system over to the new house because I fear it could make it worse. |
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New member Username: WildthingsPost Number: 1 Registered: May-06 |
I have the humm with my surround sound amp playing sound from my media computer. Not the TV or radio. I unplug the cable TV connection and the humm goes away. To elimate the humm I connected a single wire from the CATV connector to the ground prong of the electric outlet. This seems to work fine and I can't think of any issues. Anybody else know why I shouldn't do this? |
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New member Username: BlamontLos Angeles, CA United States Post Number: 1 Registered: Apr-07 |
I seem to be picking up an annoying amount of hum through my cartridge (I'm pretty sure its the cartridge). It is very low level but clearly increases as the tonearm is moved closer to the turntable motor. So this is a radiated hum pick-up problem and not a ground-loop issue. Does anybody have any suggestions on how to eliminate this type of problem? |
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New member Username: ConstrakPost Number: 1 Registered: Mar-08 |
I am not sure if I am having the same problem but I can actually receive radio channel solely on the Altec Lansing VS4121 speakers. Is anyone facing the same problem here? |
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