Radio Frequency Interference

[microstrip]

When it comes to noise and interference, the go-to expert is Jim Brown. He was past AES committee co-chair on EMI/RFI and is a Ham radio operator. He has about 50 papers and PowerPoints. Many deal with fighting RFI.

http://www.audiosystemsgroup.com/publish.htm

As long as we do not have a quantitative model of the effects of RFI on subjective effects in the sound quality of high-end systems it is useless going on quoting in general the technical experts. But yes, it looks nice in the technology section of WBF.

Ham radio deals with a limited, well defined bandwidth. As far as I know, we do not even know what frequencies we are addressing in our debates!

 

[Folsom]

Maybe the big glass window can be removed and replaced with a big slab of aluminum. The aluminum can be grounded to an earth ground. This should block RF from entering your room through that window.

A less family-friendly solution would be to wallpaper every millimeter of the inside walls, floor and ceiling of the room in which your audio system is located with thick aluminum foil. This would create a Faraday cage and should inoculate the entire room from RFI.

RF would go right around 1 pain of aluminum. It would actually crawl right around it. You'd only be able to block some of the lowest frequencies that way.

If you want to do your listening room then you can use the mesh and then paint over it with RF paint. You need to do as complete of a job as necessary.

The most important thing to think about for this process is that if you want to use Grounding Boxes then you'll only be hurting performance of them by shielding the room.





To the OP, that sounds like an annoying problem. Are you on a dedicated circuit? You should certainly turn the ethernet stuff off and see if you still hear it, before you make any conclusions. From there maybe switch off breakers in the house and check to see if any of them have something causing it. If none of that works than it's either an issue in the stereo itself or in the air... Anyways once you've done that stuff we can get to if it is in the stereo or air.

 

[Tango]

Guys. I manage my RFI effectively without doing all that. I love my windows. It’s Ron who has that crazy idea You guys can knock yourself out doing all that.

Tang

 

[Folsom]

Tang, I wasn't suggesting to treat for RF, just explaining how to do it.

Generally whatever it is that's a problem, it's fairly simple.

 

[Tango]

Tang, I wasn't suggesting to treat for RF, just explaining how to do it.

Generally whatever it is that's a problem, it's fairly simple.

I was just kidding Folsom.

Kindest regards,
Tang

 

[Alrainbow]

https://www.cgrproducts.com/blog/what-is-emi-rfi-shielding/
To help you fix your issue you first need to understand what rfi , emi are . Nest cheap,simple ways to try methods they may help the sound you hear .
Emi , rfi comes from many sources around us , cell phones , wifi and almost anything else in your home or next door devices
Even your ring doorbell as an example. Makers of devices make them not radiant above set limits but none for shielding from others.
A phono preamp with its tiny signal is perfect to be effected.
Read up first after moving or shutting off possible devices being obvious and close.
Very little is know in this hobby for it.
There is two methods to consider in emi ,rfi.
One is obvious in shielding it's the word all run to.
The second that is just as important is absorption.
Tried and error is the way to find fixes.
Good luck.

 

[Empirical Audio]

RFI is almost always picked up by ground-loops, but phono outputs are very low level. They require very good shielding and earth-grounding. The best scenario is probably to have a shield connected to earth-ground at only one end, usually at the preamp and then the preamp must be earth-grounded.

If it is a ground-loop, then you can try floating the turntable and let only the preamp be grounded.

Another option if it has to do with ground-loops is the Final Drive transformer buffer. This breaks the ground-loops.

Steve N.
Empirical Audio

 

[marty]

Can anyone recommend a good, simple, relatively inexpensive hand held meter to check for RFI/EMI?

 

[microstrip]

Can anyone recommend a good, simple, relatively inexpensive hand held meter to check for RFI/EMI?

Spectran models are well known in Europe. Unfortunately the good units are not relatively inexpensive ... http://www.aaronia-shop.com/products/spectrum-analyzer/real-time/. Starting at euro 7000.

The low cost model costs euro 500. http://www.aaronia.com/products/spectrum-analyzers/HF-2025E-V3-Low-Cost-Spectrum-Analyzer/, but covers only the mobile phone zone - 700MHz -2.5GHz band.