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Magnetic fields vs Audio gear

post #1 of 8
9/12/10 at 12:18pm
Thread Starter 

I was wondering whether CRT monitors or cell phone for instance placed in a short distance from headphones, DAC, amp, etc could create any modification and loss to the audio signal hence reducing the overall perceived sound quality ?

I guess so but have no proof except what I could imagine that may turn to be false ideas.

 

Do you guys have any knowledge to share about this subject, and some replies to provide?

 

Thanks.

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post #2 of 8
9/12/10 at 12:23pm

Yes, but not so much a loss as an addition of unwanted noise.  Anything that produces EMI/RFI close to an audio system can broadcast noise into your equipment.  There is a good description of electromagnetic interference at Wikipedia.

 

If you are having problems with this, there are a number of remedies you can try.

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post #3 of 8
9/12/10 at 12:33pm
Thread Starter 

Well, I have two 22 inches CRT monitors placed just near my DAC and amp as I cannot really use other solution. What would you recommand?

Edit : I forgot to mention I also have a CRT TV just near also, along with DECT phone. Yes, space is missing here...

 

I use no Wi-Fi and always put away my cell phone from all my gear, but I thought I may need something regarding my monitors.

 

BTW, thank you for the link I was trying to find some reading about it (related to an audio setup) during the last past half hour. I'm getting into it to see what they say about it.


Edited by Pacha - 9/12/10 at 12:43pm
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post #4 of 8
9/12/10 at 3:49pm

(1)Turn CRTs off.

(2) With no input, keep turning the amp volume knob up until you hear the noise floor.

(3) Turn CRTs on.

(4) Do you hear anything in addition to what you've heard on step (2)? If you do, how significant is it?

 

After this little experiment, you'll have a better idea about whether you should worry about the EM interference. Without the experiment, it is very hard to tell apriori as the design, execution, and relative placement of gear greatly influence the EM energy transfer. 

 

Quote:
Originally Posted by Pacha View Post

Well, I have two 22 inches CRT monitors placed just near my DAC and amp as I cannot really use other solution. What would you recommand?

Edit : I forgot to mention I also have a CRT TV just near also, along with DECT phone. Yes, space is missing here...

 

I use no Wi-Fi and always put away my cell phone from all my gear, but I thought I may need something regarding my monitors.

 

BTW, thank you for the link I was trying to find some reading about it (related to an audio setup) during the last past half hour. I'm getting into it to see what they say about it.

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post #5 of 8
9/13/10 at 3:32am
Thread Starter 

Well I've just tried that and the background is totally black with the T1 even at max volume on my C2 amp.

 

I thought a could hear with CRTs on a very slight high freq like 18KHz but I tried some more times and couldn't hear it anymore.

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post #6 of 8
9/20/10 at 6:39pm

CRT's have lots of high frequencies such as 50khz (random example) at high levels from the deflection coils, so they could influence the amp, and cause intermodulation, since most amps have less feedback / odd phase at those frequencies. There is not that much you can do, imho, except use nice shielded cables, and keep the headphone away from the CRT's (the headphone cable is also an antenna, that's how those mp3 player radios work). I think it is one of those cases where you might have been better off not knowing about. Hopefully your amp does not care about those frequencies, in which case you won't have a problem. I would say use LCDs but they have switchmode supplies and fluorescent lamps, so ...

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post #7 of 8
9/21/10 at 11:54am
Thread Starter 

I haven't heard about it before, just thought for myself of how I could improve my system and thought of this possible issue of EMI from my CRTs as I know they must generate huge magnetic fields, and thought about leaks though they are of course shielded.

I didn't thought about LCD EMI though. But with lamps which usually are Neon tubes at I guess 50Hz also... you are right they're definitely not free of issue.

What about LED displays? I guess these are ok.

 

I'm definitely not ready to go to LCD except to upgrade to a very decent one(s) like some Eizo or Lacie or Nec, and they are damn expensive.


Edited by Pacha - 9/21/10 at 11:56am
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post #8 of 8
9/22/10 at 7:52am

i use an LED backlit LCD, they are so much better than the fluorescent tube ones, yes the lighting is better, but they also run massively cooler and use less energy.  It's an LG e2240T, runs on a 12/3A mains adaptor (perhaps why the monitor itself is barely warm).

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