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Reducing Intereference in Your Speakers?
PolicyWonk asks: "I just bought a new stereo, a Sony CMT-EP707, into which I intend to plug
my laptop when watching DVDs, and my iPod when listening to music. When I first turned the stereo on I was horrified to hear interference from a local radio station, as well as a general hum emanating from the speakers. The hum and the radio emissions are audible even when the stereo's volume is set to 'min' and irrespective of what setting the stereo is on (i.e. Tuner, CD, or MD), or what input is (or isn't) plugged into the stereo. (I have tried my laptop, iPod, and no input). That means that during a quiet pause in a movie, or the intro to a song, this background noise is clearly audible. No amount of moving the speakers around the room, or plugging the stereo into different grounded outlets seems to fix the problem. I've checked my outlets, and they appear to have a ground connection, but I live on the fifth story of a circa 1900 apartment building in Manhattan, so it's anyone's guess what happens to the wires once they are in the walls. Anyone have any good solutions for reducing or eliminating interference from nearby radio sources?"
A fairly cheap method of reducing radio/TV signal interference involves just the opposite of "grounding". Go to your local Radio Shack store and get a bag full of "RFI chokes". They have several different shapes and sizes. They snap together and are supposed to be placed over wires and interconnect cables in order to prevent RF currents from flowing along the outside of the wires. You don't have to disconnect anything to install them. Just place them over the cables and snap them closed.
Hacker Media
http://www.aca.gov.au/publications/info/cbradio.ht m
Done. Now we can close this topic.
"Did you mean: Interference"
There are quite a few issues to look into. The top two would be to:
.. and for much more reasons than just the interferance, and ..
.. it may be a (semi)common problem.
a) get someone in (professionally) to test the grounding
b) try turning off hotspot applicances, like microwaves, the fridge, air conditioners -- and then try it. More sensative equipment may pick up what less sensative equipment will not.
Oh, and a final though, do a google search on your sterio equipment in case there are others who have found this problem
Robert Anton Wilson
We sometimes pick up Radio 5 on the external mike of one of our cameras - We plug a different lead in of a different length, and it just works
Interestingly it only seems to happen in theatres
My mini sound system does this too. You're going to need to buy a better system.. The mini's just aren't built for enthusiasts. They aren't built to last either. My system is 3 years old and the volume control randomly increases or decreases the volume when I turn the knob...
You might wish to ask some of the other tenants whether they've experienced the problem recently. Also, did you have a stereo before this? If this is a new problem that is specific to this particular system, I'd be inclined to return it for repair under warranty. The Sony should not only not emit significant RFI, but should reject it, too. It's not just a good idea, it's the law.
You know you can buy a ground tester at a hardware store, right?
I don't know but your landlord might be legally required to supply you with grouned electrical outlets.
The bigger the better. Place nearby. Portable! If block becomes warm, or starts to smoke, run away and find cover. Do not taunt copper block.
I'm as mimsy as the next borogove but your mome raths are completely outgrabe.
At night, from around 11pm to 6am, I hear the radio station Voice of America over my speakers. At first, I thought I was going insane, hearing quiet voices in different languages when nothing was playing over the speakers. Over headphones I don't get any interference at all, just on the speakers. It's a low end 4-speaker Koss surround set, btw, with a subwoofer. (Complaint to Koss: Don't market a surround system as 4.1 when the bass is just pulled from the front and rear channels. It's misleading and makes me wonder if the rest of your products are accurately labeled.)
I have speakers for my computer that sometimes (only for a second or two) pick up radio signals of passing aircraft and other radio transmitting devices (although I haven't actually picked up a radio station yet). This could be happening to yours and if it is - replace the speakers with different ones.
I had the same problem while trying to play DVD audio from my PC to my home stereo.
I bought an "Audio System Ground Loop Isolator" (# 270-054A) from Radio Shack for $20CDN... problem solved.
Here is a link to some info on the problem and possible solutions.
Could try filtering the power outlet. I've heard of the powerlines picking up a signal and transfering to the speakers via the AC electricity stream
If your power cables and your speaker cables are running parallel some times it turns your speaker cables into radio antennas. You can solve this either by
a) Moving your power and speaker cables further apart.
b) If they have to cross put them at a 90 degree angle to each other. This minimizes the effect.
This happened to me while I was doing sound back in High school and wireded me out until the band instructor told me about this. Same thing happened first night in the dorms in college, I thought it was my neighbors radio for the first two nights. (:
The ARRL has a web page with some information on the subject.
You might ask the engineer at the local radio station for suggestions. Even though it is not the radio station's fault, he may be willing to offer some assistance. Local amateur radio clubs can also be sources of people who are willing to help.
Ask the support department of the manufacturer of your audio device for assistance. They may have technical bulletins on how to solve the problem.
If you are asking people for help, be nice, not confrontational. Remember that it is your audio equipment, not the radio station, that is at fault. Consumer electronic equipment manufacturers could avoid most of these problems by adding less than a dollars worth of parts to their equipment. Most do not, reasoning that it is cheaper to deal with some complaints of susceptibility to RF interference than to prevent the problem.
Mea navis aericumbens anguillis abundat
You have to face the facts; that system is not exactly top-of-the-line audio equipment. But still, it seems that a $200 item shouldn't have a flaw like that right out of the box. Kind of reminds me of the new Compaq Evo computers they gave us at work. The sound hardware is horrible, and there is no isolation from the rest of the computer. So there's a continous humming, hissing, clicking and popping.
Anyway, many of the previous posters mentioned a few ideas that might help. One more thing to try though: it looks like the speakers are removable. Try disconnecting the speakers, then listening through the headphone jack. If the hum isn't there, attach the speakers and see if it returns. If the hum goes away with the speakers, then ferrite beads on the speaker wires MAY help. There is no guarantee though. The amps are probably not very carefully designed, and remember that a speaker coil has a lot of wire wound in it. That's not really a problem in FM, but remember that AM receivers use a lot of thin wire wound around a magnetic core...like a speaker. If this is the case, the speakers sound pretty cheaply made as well.
If the interfering station is AM, then you have an idea of where to try to fix this. Personally, the best solution seems to be returning the stereo. Find another model/brand, and if it doesn't have the annoying noise, the problem is solved. You can waste a lot of money on voodoo powerstrips and filters, and waste a lot of time fretting about the noise, wiggling different metal objects in the room, and twisting cables around just so. Just pack it up, take it back to the store, explain your problem, and say you'd like to try a different model.
On a side note, good quality speaker+subwoofer-only systems can be had for much less than $200. That would be my first approach to amplifying laptop and iPod audio. Check your store's computer section. I've never even paid for a set of computer speakers; one set came from a technical college that didn't want their bundled Labtec speakers; another set was free from a friend. Actually, on that last set I kept the subwoofer/amp section and threw away the cheap satellites...and used the speakers from a dead Sony bookshelf system. The sound is clean, and a bit more powerful than 15 watts per channel.
...
... it was two different grounds. One from the computer (and thus from the power outlet), and the other from a common antenna outlet that carries radio and TV for the whole house. Although the grounds are connected at the roof, with me living on the first floor they're not acting like connected for high frequencies anymore.
I solved the problem by disconnecting the stereo from the common antenna and using my own antenna to receive radio.
Conclusion: Always use one ground only. Star/tree topology is a must for grounding. Never create loops.
If it's at all connected to your TV, VCR, or anything that connects to a cable TV system, the system may be the culprit. I had to take one of these and one of these, connected them back-to-back, and ran them inline with every cable line in my house. Evidently the cable system was wired by an idiot, and the distribution amps on the pole (or something like that) aren't very good quality.
:D
Try it and see. I bought 50 of each of those adapters, spent 20 minutes, and went door-to-door in my apartment complex asking if they had a problem with hum on their stereo system. Sold 'em for $3 apiece.
Hey Taco! Looks like you're using the "infinite monkeys and typewriters" scheme to generate Ask Slashdots again...
If you bought it mail order then go to a couple of different friends places with it and try it there to see if location makes a difference. Even the specifications link doesn't say if this thing has to plug into the wall or if it can run on battery power, but if it can, see if using batteries instead of wall socket AC makes a difference.
E-mail me if you need further info or advice.
I see even classic Slashdot is now pretty much unusable on dial up anymore.
This shouldn't happen.
As previous posters have said, electronic equipment should not emit radition, nor accept radiation. In most western countries, this is part of law.
If your speakers are accepting radiation, then chances are they may well be a source of unwanted radiation too.
I'm suprised that Sony would have such a design flaw, so I think the problem is specific to the actual speakers you have -- i.e. my guess is that they are broken.
Take them back for either exchange or refund.
"The noble art of losing face will one day save the human race"---Hans Blix
I used to randomly hear short interjections of the conversations between CBers on my home stereo. The funny thing is, I'd swear it was the same guy every time, although I only heard a few seconds at a time, so who knows. All I had was an NAD CD player directly feeding into a Parasound amplifier, with nothing but 1/2 meter Audioquest interconnects connecting the two. Nevertheless, once in a while I'd suddenly hear 4 or 5 words come crackling out of the speakers, in and out like a flash. It was quite spooky until I figured out that it must have been truckers going by on the highway, which was about 1 mile away from my apartment.
-- Never hit a man with glasses. Hit him with a baseball bat.
I have nothing whatsoever to contribute to fixing your problem, except say, try different speakers or move the system to another room or apartment and see if the problem follows.
on the other hand, I've had this annoying beep-tone thru my computer speakers ever since I had SouthWest Bell DSL installed last year. It never happened on my previous DSL install. This beep-tone randomly comes and goes and seems to be related to when you click on something when someone is talking on the phone, but it doesn't happen all the time and the length of time the beep-tone plays is anywhere from a quick chirp to a 5-10 second long note.
beats the hell out of me what's causing the issue.
Heh, somewhat similar to this, I was setting up for a Vocal Jazz performance at a golf club, when all of a sudden, We started to hear a radio station. Nice to know it just doesn't happen to you.
Baver
then try here for a cheap price. The Griffin Technologies iMic has both input and ouput options superior to your laptops built-in soundboard.
Choosing the lesser of two evils is a choice for evil.
Cheap gear + cheap wires = bad sound. /rebuilder, but since that sort of a solution will cost around $2000-$10000, you might buy a cheap power conditioner meant for a computer. They suck in relative terms, but they might help in your situation.
This is why people spend thousands on higher quality audio gear. My best suggestion is return the junky equipment and go to a hi-fi stereo shop in your area (NOT someplace like Best Buy) and get some good gear. If that is not an option, consider just buying higher-quality shielded speaker cable. Regarding the constant hum you are hearing, that is probably not interference from a radio station, but rather it is probably from AC power. Make sure you don't have any switching power supplies nearby and then make sure that your power cables for and signal cables (stereo interconnects, speaker wire) cross at right angles only. If you remember high school physics, you should quickly remember why. Finally, crappy AC power will cause hums as well. Real enthusiasts usually have a dedicated power line for all their audio gear plus a power conditioner
I have similar experiences with my audio equipment. I live about 500 meters from a light house where there is a 1KW morse code beacon. Unfortunatly just a bit of speaker wire ia all that is needed to recieve the signal. I end up hearing the beacon through my PC speakers and on recorded minidiscs(I don't have spdif).
During my ham radio training I learned a reason why this could happen. In many speaker systems you will find a crossover unit. This is basicly an inductor(coil) and a capacitor. This forms a tuned circuit that is designed to accept or reject signals of various frequencies. In som e cases the small amount of signal picked up by the speaker leads is enough to turn your speakers alone into radios.
I have even heard of rusty old fences "tuning in" to radio stations and amazing passers by.
btw, our local(Durban, South Africa) ham radio group set up a field station at the above mentioned light house a few years back. Forgeting about the beacon, they wondered why there were sparks between the antenna leads and a grounded bus bar on the desk. 1KW at 2m from your antenna can be rather scary.
I've worked with sound reinforcement for a while, and a few times we just pick up radio on things. It's usually a grounding problem with a guitar or keyboard. Solution? Defeat the ground. For us, we flip a switch on a little blue box. For you, it'll probably look like a ground cheater (those little thingies that have three holes in but only two prongs out). If you only have a two-pronged cord, then you might consider getting the "inverse" ground cheater (two holes in, three prongs out, and a little tab on the two-hole side) and ground the case of the stereo (or since it's probably a plastic case, run a wire from under a screw on the back to the little tab).
You've all seen the symptoms (I hope) - place a monitor and a laser printer on the same circuit, and power cycle the laser printer, and the monitor will "wave." I have a monitor that does this 24x7. I've tried different AC circuits to no avail. Audio on this (Compaq) PC is also odd, but the monitor is rock solid on other PC's - and it's new too.