Detecting EMF/EMI around your equipment

Bob in St. Louis · « **on:** 3 Jan 2009, 12:58 pm »

Hello there,
I've been thinking about electromagnetic fields swirling around my equipment rack and how to detect, and therefore repair or minimize these fields.
I'm looking for advise on an inexpensive piece of test equipment to make these measurements. After a little searching I've found units from $25 to $1,500.
I've found a website called> "LessEMF" <that sells a wide range of testers. This page has several reasonably priced units that have peaked my interest. Some of these units are a DMM/DVOM attachment which would work for me as I do have a Fluke 83.

Any thoughts, advise or opinions would be appreciated.
Thanks fellas!

Bob

Levi · « **Reply #1 on:** 3 Jan 2009, 03:08 pm »

Hi Bob,

Check out Sencore. Depends on your location, you can hire someone to analyse various RF interfernce around your equipment. They make good tools however, very expensive specially if you are only going to use them ones or twice. Probably better off renting or hiring a professional.

Just a thought. Sencore dot com

Levi

Russtafarian · « **Reply #2 on:** 3 Jan 2009, 05:15 pm »

There's always the AM radio trick. Tune a portable AM radio to an open frequency and move it around your gear. The more noise you hear, the more that component and/or cable is kicking out trash. Granted, this is RF rather than EM, but it's cheap and easy to try.

Russ

satfrat · « **Reply #3 on:** 3 Jan 2009, 05:31 pm »

Just to mention tools I use to combat EMI/RFI inside my compaonents, I use Audio Magic's Pulse Gen ZX active conditioner that deals with these issues directly at the source. I use these units inside all my components that includes not only my DirecTv HD DVR but my breaker box also. Even with everything I've done to combat these issue from outside the components, these little active 1" x 2.5" boxes make a substantial contribution that's readily noticable. If post this isn't appropriate for the Lab Josh, please feel free to toss it but considering the issue of EMI/RFI that's generated from within components and how to detect it is being discussed, maybe an example of how to deal with it from within would be of some interest.

More about this little gem can be found here.

Cheers,
Robin

jeffdavison · « **Reply #4 on:** 3 Jan 2009, 05:59 pm »

have fun trying to control all the fields all the time!
http://gizmodo.com/5012347/nasa-scientists-make-magnetic-fields-visible-beautiful

Bob in St. Louis · « **Reply #5 on:** 3 Jan 2009, 06:11 pm »

Levi - Thanks for the link!
I searched through their site and could not find the specific devise I'm looking for. Although they do have some very interesting toys that distracted me from my main goal. ha ha
I'm wrong in thinking this way, but the general "feel" of the site, it does seem their products are "high-dollar professional use" and beyond my means.
A pro coming out is most likely out of the question as well for a couple reasons; This is something I'd like to check occasionally as I swap components, cables, etc... over the years. And #2, again, the cost would be prohibitive.

Russ - Neat trick! Can you provide a link to where I could buy an AM radio?

Actually, that does sound like an interesting test, indeed.

Any opinions on the site I linked to? They've got several units that look like possibilities.

Bob

Edit;
Robin, and Jeff - Thanks for the links, I'll check those out right now.

Niteshade · « **Reply #6 on:** 3 Jan 2009, 06:27 pm »

Are you having EMI problems? If so- what are you hearing?

If it's low frequency RF, a pocket radio with the AM band will pick up allot of garbage.

I have seen ALLOT of problems caused by electrical conduits inside walls. If something is around one that's vertically orientated, they can cause issues. Horizontal wiring isn't as bad most of the time.

Brown · « **Reply #7 on:** 3 Jan 2009, 06:39 pm »

Quote from: satfrat on 3 Jan 2009, 05:31 pm

Just to mention tools I use to combat EMI/RFI inside my compaonents, I use Audio Magic's Pulse Gen ZX active conditioner that deals with these issues directly at the source. I use these units inside all my components that includes not only my DirecTv HD DVR but my breaker box also. Even with everything I've done to combat these issue from outside the components, these little active 1" x 2.5" boxes make a substantial contribution that's readily noticable. If post this isn't appropriate for the Lab Josh, please feel free to toss it but considering the issue of EMI/RFI that's generated from within components and how to detect it is being discussed, maybe an example of how to deal with it from within would be of some interest.

More about this little gem can be found here.

Cheers,
Robin

Great products robin. Was stunned by their performance. Definitely on the short list. Thanks for sharing I was to timid to do so, actualy just did not want the foobydust crowd to jump in.

satfrat · « **Reply #8 on:** 3 Jan 2009, 06:53 pm »

Quote from: Brown on 3 Jan 2009, 06:39 pm

Quote from: satfrat on 3 Jan 2009, 05:31 pm
Just to mention tools I use to combat EMI/RFI inside my compaonents, I use Audio Magic's Pulse Gen ZX active conditioner that deals with these issues directly at the source. I use these units inside all my components that includes not only my DirecTv HD DVR but my breaker box also. Even with everything I've done to combat these issue from outside the components, these little active 1" x 2.5" boxes make a substantial contribution that's readily noticable. If post this isn't appropriate for the Lab Josh, please feel free to toss it but considering the issue of EMI/RFI that's generated from within components and how to detect it is being discussed, maybe an example of how to deal with it from within would be of some interest.

More about this little gem can be found here.

Cheers,
Robin

Great products robin. Was stunned by their performance. Definitely on the short list. Thanks for sharing I was to timid to do so, actualy just did not want the foobydust crowd to jump in.

HEY, it's a chance you have to take. If you believe in a product or certain philososphy, you need to stand behind it. But I understand how you feel, unfortunately many believers and product owners stay silent while the many naysayers out there have no problem jumping on an opportunity when it presents itself. But it's their right and one has to respect that right.

It's just ashame more folks wouldn't come forward and express their opinions on stuff that they've tried or are now using in their systems. Thnak Brown for stating yours.

ps, I also use the RGC-24 grounding unit on my processor and the RR-77 for the whole room.

Cheers,
Robin

Bob in St. Louis · « **Reply #9 on:** 3 Jan 2009, 07:17 pm »

Quote from: jeffdavison on 3 Jan 2009, 05:59 pm

have fun trying to control all the fields all the time!
http://gizmodo.com/5012347/nasa-scientists-make-magnetic-fields-visible-beautiful

True to form, you guys really know how to find the cool stuff. aa
That's amazing. I'm sure I'll be searching for more information on that. Thanks for the link!

Robin, I (kinda) understand the point of that little devise (controlling internal EMF), but with the amount of components I have, it's CERTAINLY out of the question at $400 per component. Plus, what does it do for all the upstream trash coming in through the power cables.

My goal here is to measure how intense of a field I have at my equipment rack. (I can visualize one Helluva lightshow if NASA brought their toy into my room.

)
Then when I get around to making new cables for all of my equipment, I could remeasure what I've accomplished.
So to answer Nightshade's question, I'm really not having a "problem" per se, nor am I hearing anything "wrong". It's just that I'm convinced if I 'tamed' the fields, it couldn't hurt anything and if things go as I think they might, It's very possible I might just have an improvement in sound quality than I presently have.

Bob

EDIT; Jeffdavidson - I found a longer video of that "Magnetic Movie". Very cool.
I'm going to post a link in the Sports Bar thread "Cool YouTube Videos".
Thanks!

JoshK · « **Reply #10 on:** 3 Jan 2009, 07:53 pm »

If you have liberty to move equipment around, space is the ultimate tool against EMI interactions. EMI field strengths drop exponentially with distance. To see if EMI is a problem for you, try moving your components away from eachother, couple feet should do. Does it make a very noticeable difference?

As previous posters said, RFI is a totally different animal. Its high frequency, not low like EMI. The AM radio trick is the one I hear most often quoted. Seems to work better than most expensive equipment.

Paint me skeptical but I am leary of multi-hundred dollar "fixes" that can't come up with good scientific explanations for why they should work. Plus anything used to combat EMI fields changes EMI fields. That change will have an effect on the operation of that which put it out, but not always a good effect. Without tools and understanding of what you are doing, you are throwing s**t against the wall to see what sticks. (not trying to be combatitive, trying to explain why I'd rather not go down that road).

P.S. if your component is throwing off RFI, it means it is likely oscillating, or has massive quantities of switching noise that isn't properly dealt with. If the RFI is coming from your environment and getting into your component, that can be addressed through shielding.

Niteshade · « **Reply #11 on:** 3 Jan 2009, 08:04 pm »

How about this for an EMI detector:

Take a unused input from your preamp, plug in a patch cord that has the shielding taken off around 5 inches from the other end. Now you'll have a wand that can sniff out EMI. You may want to trim the unshielded wire or choose to start out with more than 5 inches and then trim until you can make it localize noise better. You could even start out with enough unshielded wire at the other end to make a loop if you require a more sensitive detector.

Just a thought!

Have some fun with it for cheap! Try variations of this, etc...

Browntrout · « **Reply #12 on:** 3 Jan 2009, 08:19 pm »

Interesting topic. I think what was said about space between components is correct and the comment regards field interaction is also spot on, the correct approach is to have nothing but space and certainly no magnetic/ferous material in the range of the fields.
I think the proper way to combat EMI and RFI is to treat the walls partially with ERS cloth (or similar), avoiding any change in the fields created by components but limiting outside interference. It is also possible to use too much of this stuff, the installs I've seen have the paper stuck to the walls only half way up and forming a u shape around the stereo as in back wall and some of side walls.
Keeping components and cables away from each other is the best solution.

Bob in St. Louis · « **Reply #13 on:** 3 Jan 2009, 08:37 pm »

Thanks Josh,
I think I'm still not making myself clear.

Sorry about that, lemme try another way;
- I have a rack full of O.E. power cables.
- I think I'd get better sound quality if I could shield/stop/eliminate EMI/EMF
- I want to make new cables
- I'd like knowledge of "before and after" to see if I've made a difference.

That clear it up?
Bob

JoshK · « **Reply #14 on:** 3 Jan 2009, 08:51 pm »

Sorry, I guess I didn't read well enough. I skim quickly sometimes. Its a habit of my occupation. I missed the part about the cables.

Still one way to experiment with effects of EMI in cables is to move the cables close together and further apart and try to see if there is a difference. Tedious though. There might be equipment to test, but I bet it is expensive.

A while back (maybe 1-2 years) I mentioned an idea for keeping cables neater, organized and away from eachother using a stretching mesh thingy, like the thing made for the back of SUV's to hold stuff from flopping around. If you fixed it to the back of your rack, standing off some inches then you could route your cables through the loops to keep them away from eachother. Space is your friend with EMI.

Regarding how to make cables effective against RFI/EMI, well we can discuss that too if you like.

Bob in St. Louis · « **Reply #15 on:** 3 Jan 2009, 08:59 pm »

Niteshade - I like the idea of an unshielded preamp wire. That's definitely the most interesting idea yet....and free too!

Trout - (and others) I've got all of my equipment in a vertical rack that's almost 7' tall and build into the wall. There's no way I can separate my equipment, and darned hard to separate cables (very far) from each other.

I've bought some Home Depot "Phillips" brand Velcro straps for bundling wires. My plan was to tie all the AC stuff away from the ICs and Highlevel wires, but I wanted to take this a step further.

Josh, I wouldn't mind talking about cable construction, but I needed (wanted to) know where I'm at in regard to EMI/EMF first. Just to know if I made a difference. But there's a lot of info I want to research about cable construction before I ask redundant questions here.

gotta go, sorry for typos......

Bob

edit; {for horrible typos and grammatical errors}

Niteshade · « **Reply #16 on:** 3 Jan 2009, 09:03 pm »

Hello Bob,

Don't assume you have problems if there is no detectable side effects. Don't go crazy with this! Do some simple tests first before spending oodles of time & money.

You know what they say- if it isn't broke, don't fix it.

JoshK · « **Reply #17 on:** 3 Jan 2009, 09:03 pm »

Quote from: Bob in St. Louis on 3 Jan 2009, 08:59 pm

Niteshade - I like the idea of an unshielded preamp wire. That's definitely the most interesting idea yet....and free too!

Bob

I like that idea too. Very interesting. I will have to try that out, to see what I can see.

Bob in St. Louis · « **Reply #18 on:** 3 Jan 2009, 11:21 pm »

Quote from: Niteshade on 3 Jan 2009, 09:03 pm

Don't assume you have problems if there is no detectable side effects. Don't go crazy with this! Do some simple tests first before spending oodles of time & money.

You know what they say- if it isn't broke, don't fix it.

Ohhhh, dude..... No, no, no......

......You're not following me, you don't understand.
That would spell the end of this hobby for me right here and right now.
I'm so happy with my system the way it is today, I could just S___ myself.
I'm not having any problems, and I don't have any complaints.
But if it where that simple........If that where the case; then how about you and your amps? Is there something wrong with them? If not, then WHY would you continue building new ones, different ones, better ones, 'improved' ones?

But that's not the point with audio is it?

With all due respect Sir, this is more than a hobby, this is a full fledged addiction. Being a home theater guy in addition to two channel, it's a double whammy regarding addictions.

Regarding performing simple tests before spending a bunch of money, that's the entire point of this thread. The elusive answer I'm in search of is that the website I linked to has many devises designed to 'sniff out' EMF. All I'm asking is which one (if any) would work for what I'm asking......Or, does somebody know of a better way/devise. I have ZERO desire to spend a bucket of money to search and destroy EMFs. But if I can do it "on the cheap", then by all means, I'll do it. I AM assuming I have a problem since I've got ten pieces of equipment in my rack and the power cords range from O.E. common zip cord to decent (looking) O.E. cords. None of them are shielded, and I doubt any of them have much of a twist to the conductors. Also in the rack is a UPS and a couple cheap power strips. So.....Do I assume I have a problem? You're darn right. In this rack is the potential for 1,625 watts (both tube and SS). That's a lot of potential for some EMF interference don'tcha think?
So, again...... do YOU assume I might have a problem with EMF? Do you think my system may be a *little* "broke"?
How about some room for improvement regarding cable construction, shielding, etc.... to minimize "the nasties".
Yea, I think so too.
But you're right, I won't go crazy with this. At least not financially crazy.
But when the day comes I start buying bulk material to build all new power cords, innerconnects, and line level cables, I'll be going a little crazy.

I just have an overwhelming desire to know what I'm starting out with and how good of a job I've done when I build my first power cable. I shudder to think I'd spend all that time and money to make ten power cables and made things worse than I started.

Bob

markC · « **Reply #19 on:** 4 Jan 2009, 12:30 am »

Bob, I think you should try a couple of cables at a time. See what happens. And yes, I "get" why you want a device to tell you whether or not you've improved the situation.