Problem with electrical outlet -- noise

Feb 3, 2003 at 9:38 PM Thread Starter Post #1 of 19
slonik

slonik

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Hopefully this is the right forum for this, but here's my problem. I have an amp. When I plug it into the outlet at home, I hear a radio FM channel even though the amp is not plugged in into any source. The same thing happens with my computer loudspeakers.

I have this problem only at home, and although I don't understand how this is happening, my guess is that the outlets do not have shielding.

Is there any way to fix this with some radioshack gimmick or something like that? It would be hard to reach my landlord to get this problem with outlets fixed.

Help!
smily_headphones1.gif
 
Feb 3, 2003 at 10:07 PM Post #2 of 19
I have had this problem twice, but is not the technical guru who can give the best answer. Reason is that you get radio frequency interference somewhere. Wires in the amplifier, interconnects and AC wires work like antennas. I have only experienced this problem on phono where the input level is low, only a few millivolts.
First time was twenty years ago when there was a radio amateur with a sender in a nearby flat. I could here him on the turntable. This problem solved itself because he moved after a short time.
Second time was then I bought a phono preamp a year ago. This problem also solved itself. Seams that it became less disturbing after a burn-in of the amplifier and also when I rewired the tonearm with better grounding, when it completely disappeared. Could also be that the source of disturbance disappeared, I have no idea of what the source was in this case.

In your case a beleive that the interference is air-born.

Some things can be done, I hope others have better ideas:

Move the components within the room, especially away from windows.

Use interconnects that are shielded.

Try shielded power cables and perhaps some kind of powerline filter.
 
Feb 4, 2003 at 2:22 AM Post #3 of 19
but it sounds like you have a poor ground on the electrical circuit. All the suggestions made previously will help.

I fixed this problem at my home by setting a new ground pole, 8 ft of copper plated steel in the ground (dirt) and fasteing a ground wire from the electircal service to it. While I was at it, I grounded the phone line and cable feed to the same thing. You can kill yourself doing this.

Your whole electrical service could be the problem or it good be the one outlet. Try another one. Try one at someone else's house, since it could be your equipment.

If you can't do any of this, then perfectly shielded interconnects should pretty much eleiminate the symptom.

Good luck.
 
Feb 4, 2003 at 2:35 AM Post #4 of 19
Thanks for the suggestions, guys.

The equipment (audio technica AT-HA2 amp and HD280) seems to work just fine at work. It's probably the appartment, I tried 3 outlets and all of them have this problem. The building is quite old, dates from 1910, so maybe the outlets are just as old, then
smily_headphones1.gif


This *really* gets on my nerves, but the noise is not even constant, and moving the amp/cables makes a difference.

I'm definitely not going to attempt fixing the outlets themselves, so the next step is probably radioshack. The thing is, the amp has a particular power supply, so I don't think I can find a replacement easily. Is there some sort of filter I could buy to use between the amp's power supply and the outlet?

This sucks
smily_headphones1.gif


Thanks again!
 
Feb 4, 2003 at 3:44 AM Post #5 of 19
Actually, I believe you can get RF Chokes at radioshack for a few dollars. I think they would solve all of your problems quite quickly. . .
 
Feb 4, 2003 at 4:28 AM Post #6 of 19
Feb 5, 2003 at 1:09 AM Post #10 of 19
you may also want to put ferrite beads on all of your ac cords. (try radio shack).

hope you don't live with 100 feet from an FM station or ham radio antenna.

those EMI filters are only good for 5 amps. chances are they'd blow up in a regular amp. but you can buy something like it at Radio Shack. and of course they make ac outlet distribution panels with emi circuits built in.
 
Feb 5, 2003 at 2:30 AM Post #11 of 19
If you have multiple things to plug in, you might want to just buy a Tripp-Lite 6-plug filter/distribution strip/surge protector.

Tripp-Lite has good EMI filtering built in (and it cascades, so the first pair of plugs are filtered, the second pair is filtered again, and the third pair is filter one more time.)

Plus it will protect your equipment from lightning! Just a thought.
 
Feb 26, 2003 at 2:55 AM Post #12 of 19
Sorry about bringing the thread back from the dead, but I just got a Belkin surge protector thingie. It claims that it "filters EMI/RFI noise up to 43 dB reduction"

Of course, it makes absolutely no difference to me at all. There's still noise coming from the amp.

What's weird is that my cheapo stereo doesn't have this problem. Just computer speakers and the amp.

Couldn't find the things you guys have mentioned in my RadioShack (Canada). The people there have no idea what I'm talking about.

The horror... the horror.
 
Feb 26, 2003 at 4:05 AM Post #13 of 19
Quote:

Originally posted by JahJahBinks
I just opened up my Reality amp, and inside there is one very similar to that connected to the power in.

Oh, the components inside Reality look complicated, ha!


Xin,

First thing, get rid of that filtering IEC inlet. Replace it with an Acme Audio Labs silver coated cryo treated IEC that has no components in it. This will open up the high end of the REality when you replace it. it is VERY easy to replace as the power wires have a sleeve that fits right onto the old and new IEC inlets. I wish I could send you mine, but it's sitting here with me now. I might instal it on my CDP, but we'll see.
 
Feb 26, 2003 at 4:32 AM Post #14 of 19
Quote:

Originally posted by wallijonn
think this would help, an emi filter?

http://cgi.ebay.com/ws/eBayISAPI.dll...309530922&rd=1

i was going to DYI a meta. since i no longer going to, i will be tracting my bid.


I saw some people removing this devices (you may ask why pinkfloyd removed the one on their xcan ps, maybe he has more info about that) from the equipment as they stated the degrade the suond signal, and they noticed a better sound without it, so maybe you get a quiet sound but not the same, but this is what I have read, nothing for sure, better find out, before going on this route....
 
Feb 26, 2003 at 4:53 AM Post #15 of 19
Quote:

Originally posted by ServinginEcuador
Xin,

First thing, get rid of that filtering IEC inlet. Replace it with an Acme Audio Labs silver coated cryo treated IEC that has no components in it. This will open up the high end of the REality when you replace it. it is VERY easy to replace as the power wires have a sleeve that fits right onto the old and new IEC inlets. I wish I could send you mine, but it's sitting here with me now. I might instal it on my CDP, but we'll see.


Where did you get it from?
 
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