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#1
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Help with speaker noise
I'm asking this question on the rec.audio forums because there seem to be a
lot of technical experts who have helped with these kind of problems in the past. Anyway I am bashing my head against the wall because my computer speakers (Altec Lansing ACS45 2 speakers & sub) which worked fine at my apartment, now emit a very annoying hum/buzz whenever they have power. I thought the speakers or built-in amp was broken, so I purchased some new speakers (fairly cheap Cyber Acoustics ones, also 2 + sub), only to find the exact same problem with them! Here are the symptoms and results of my testing so far: 0. My ACS45 speakers always did have a bit of static 'snow' whenver turned on, but it was barely noticable when I lived in my apartment. 1. Speakers emit buzz/hum whenever they are plugged into AC and are turned on. You can also faintly hear a radio station or other music. This buzz/hum does not change with volume adjustment, nor does being connected to my computer's soundcard affect it. In fact, I plugged them into the AC outlet in my kitchen and found the exact same noise. Playing with the wires' orientation does affect the noise somewhat. 2. When I tried them at my neighbour's house, the buzz/hum was NOT present.. 3. When I try them in my unfinished basement (plugs are near the main wiring panel), the buzz/hum was also NOT present. 4. Using a ferrite bead/core which I stole off a modem line that came with my laptop, had almost no effect. 5. I do have an APC surge suppressor, but it's a fairly cheap one that I don't think does much noise filtering. At first I suspected a 'ground loop' problem but I don't think it's that because it happens when my speakers are attached to nothing except AC power. I still suspect noise in my electrical lines, which goes away in the basement because so close to the main house wiring & ground? I also suspect Radio Interference, as there is a radio tower nearby. This would explain the music heard in the background, and going to the basement (below ground) might offer some shielding. Although it doesn't explain why the problem doesn't exist at my next-door neighbour's house. Sorry for the long explanation. Right now I'm thinking of doing two things: getting some higher quality speakers, and getting a higher quality surge suppressor with at elast 70db of EMI/RFI reduction. Thanks for any help or suggestions as I am having a very hard time with this! Mike |
#2
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Help with speaker noise
"Mike & Kristen" wrote ...
I'm asking this question on the rec.audio forums because there seem to be a lot of technical experts who have helped with these kind of problems in the past. Anyway I am bashing my head against the wall because my computer speakers (Altec Lansing ACS45 2 speakers & sub) which worked fine at my apartment, now emit a very annoying hum/buzz whenever they have power. I thought the speakers or built-in amp was broken, so I purchased some new speakers (fairly cheap Cyber Acoustics ones, also 2 + sub), only to find the exact same problem with them! You might want to have your house wiring checked. You could have a faulty ground or something. This could have actual safety implications far beyond annoying noise in your computer speakers. Here are the symptoms and results of my testing so far: 0. My ACS45 speakers always did have a bit of static 'snow' whenver turned on, but it was barely noticable when I lived in my apartment. The generally-accepted term for this is "hiss". Like what you hear on an FM receiver between stations. People will know what you are talking about if you use the proper terms. Most of these cheap computer speakers with built-in amplifiers have some amount of audible hiss. Goes with the territory. 1. Speakers emit buzz/hum whenever they are plugged into AC and are turned on. You can also faintly hear a radio station or other music. This buzz/hum does not change with volume adjustment, nor does being connected to my computer's soundcard affect it. In fact, I plugged them into the AC outlet in my kitchen and found the exact same noise. This is what makes me think something may be wrong with your power mains wiring. Have it checked by a quallified (licensed) electrician. Playing with the wires' orientation does affect the noise somewhat. Are you SURE that you are using the proper SHIELDED wires? 2. When I tried them at my neighbour's house, the buzz/hum was NOT present.. Again, another symptom that points to a systemic problem in your house wiring that is not present in your neighbor's house. 3. When I try them in my unfinished basement (plugs are near the main wiring panel), the buzz/hum was also NOT present. Could be because... a) These plugs are wired properly ("after-market" improvement?) b) You are more shielded from the nearby transmitter. 4. Using a ferrite bead/core which I stole off a modem line that came with my laptop, had almost no effect. Depends on where you put it (power lead, signal leads, etc.), and depends on what is design characteristics are. Most likely designed to "snub" sharp wavefronts from digital signals, not to surpress 60Hz hum (or broadcast radio waves). 5. I do have an APC surge suppressor, but it's a fairly cheap one that I don't think does much noise filtering. Not clear whether any of these tests were WITH or WITHOUT this surge surpressor. Does in/out make any difference? At first I suspected a 'ground loop' problem but I don't think it's that because it happens when my speakers are attached to nothing except AC power. Good observation. I would agree. (Assuming you have the proper *shielded* audio wires going to the input of the speaker amp). I still suspect noise in my electrical lines, which goes away in the basement because so close to the main house wiring & ground? I would suspect bad mains grounding rather than noise (or causing the noise). I also suspect Radio Interference, as there is a radio tower nearby. This would explain the music heard in the background, and going to the basement (below ground) might offer some shielding. Are you getting increased interference in any other equipment? Phones, radio, TV, cable, etc? In the US, the people transmitting are obligated to help you eliminate any RFI. Dunno if it is the same in Canadia? Although it doesn't explain why the problem doesn't exist at my next-door neighbour's house. Did they EVER have a similar problem? Did they already solve the same problems you are now seeing? Where are they relative to the transmitting tower? Sorry for the long explanation. Right now I'm thinking of doing two things: getting some higher quality speakers, Don't commit yourself to buying ANYthing until you show that it will actually WORK in your situation. You have already proved that it is UNLIKELY to be the fault of the speaker by trying two different speakers. and getting a higher quality surge suppressor with at elast 70db of EMI/RFI reduction. I wouldn't put too much hope in those things unless you can actually show that it works in YOUR situation. They are largely marketing gimmicks. I'd certainly investigate the transmitting tower more before throwing any more money at potential bandages. Who is transmitting? Is it the same radio station whose music you hear in the interference? have any of your neighbors had similar problems with RFI? What is the age of your house (specifically the wiring)? Was it inspected when you bought it? |
#3
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Help with speaker noise
Hi Richard, thanks for you quick response. Sorry if I a bit lacking in audio
terms and knowledge. Some responses for you: Playing with the wires' orientation does affect the noise somewhat. Are you SURE that you are using the proper SHIELDED wires? The ACS45 has shielded wires, playing with those wires' orientation doesn't have any effect. The new speakers I bought (which I've sinced returned) didn't have shielded wires; playing with those ones did affect the noise. 5. I do have an APC surge suppressor, but it's a fairly cheap one that I don't think does much noise filtering. Not clear whether any of these tests were WITH or WITHOUT this surge surpressor. Does in/out make any difference? The surge suppressor does not seem to make any difference. I'd certainly investigate the transmitting tower more before throwing any more money at potential bandages. Who is transmitting? Is it the same radio station whose music you hear in the interference? have any of your neighbors had similar problems with RFI? What is the age of your house (specifically the wiring)? Was it inspected when you bought it? I'm not sure who broadcasts through the nearby (~ 400 yards/meters) tower. The music is faint so it's hard to tell what station it may be. The house is less than a year old, and it was inspected by a city electrician when built (we purchased the house from a builder). My neighbour did mention having problems with a self-powered subwoofer picking up what might have been RFI. He changed its location in the house and that solved the problem. My house is between his and the tower, although there are also umpteen houses between me and the tower. |
#4
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Help with speaker noise
"Mike & Kristen" wrote ...
The house is less than a year old, and it was inspected by a city electrician when built (we purchased the house from a builder). Doesn't mean there might still be a problem. Inspectors aren't perfect. Especially if you bought the house new, it has no history. Can you plug an extention cord into the basement plug and move the speakers around (even upstairs). That would do a differential diagnosis whether it was the plug or the location. (And other similar differential experiments.) My neighbour did mention having problems with a self- powered subwoofer picking up what might have been RFI. He changed its location in the house and that solved the problem. It sure sounds like you're in the "RFI Zone" My house is between his and the tower, although there are also umpteen houses between me and the tower. How many of THEM have had RFI problems? |
#5
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Help with speaker noise
That's a good idea about the extension cord. I will give it a try.
Good news, I purchased some new speakers today (Logitech X-220) and they are much better, hiss is not detectable unless you put your ear right to the speaker, and no buzz or radio station! I guess you get what you pay for. I do still plan to try and diagnose the problem with the old speakers, I will ask more neighbours about RFI and possibly give my builder a call about the wiring (house is under full warranty for another 2 months). The really funny thing was I was able to determine what radio station I was picking up, it was "VIBE 98.5" an R&B station here in Calgary. "Richard Crowley" wrote in message ... "Mike & Kristen" wrote ... The house is less than a year old, and it was inspected by a city electrician when built (we purchased the house from a builder). Doesn't mean there might still be a problem. Inspectors aren't perfect. Especially if you bought the house new, it has no history. Can you plug an extention cord into the basement plug and move the speakers around (even upstairs). That would do a differential diagnosis whether it was the plug or the location. (And other similar differential experiments.) My neighbour did mention having problems with a self- powered subwoofer picking up what might have been RFI. He changed its location in the house and that solved the problem. It sure sounds like you're in the "RFI Zone" My house is between his and the tower, although there are also umpteen houses between me and the tower. How many of THEM have had RFI problems? |
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