Anyway to shield speakers from interfering with a CRT monitor?

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purbeast0

purbeast0

No Lifer
Sep 13, 2001
53,251
6,101
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So the other day I realized that what I thought was a degaussing issue with my KI2 cabinet was actually because it's close to my surround speaker.

I pulled my cabinet out from the wall next to the speaker, and what would you know, the discoloration went away.

image0.jpg


I tried putting a sheet of steel sheet metal around the side of the cabinet but unless it was in a very specific place, the distortion was there. And even then, I think it was still there just not quite as bad.

Today I messed with it a bit more.

I need to remove 2/3 of the drivers to completely remove any interference. If I kept that middle one in there, then it still was having a little bit of distortion.

zo2DpzB.jpg


Here are pics of the drivers. The one on the left is the center driver. The one on the right is the outer one and is identical to the other outer one. It looks like the one in the middle has something on the rear of it that plugs into some wires inside the speaker. I'm guessing it's a little tweeter driver but I'm a noob with this so that is just me making an educated guess.

Also, the driver appears to be 5.25" in diameter, and the magnet is pretty dang strong lol.

7Y28GFc.jpg


Here is the rear of one that goes in the center with what I think is the tweeter on it.

s5FXKdU.jpg


And here is the rear of the one that is on the outer side.

Yy32D3H.jpg


I had heard of this thing called a bucking magnet but I don't think that can work with the middle one because there is a tweeter on the rear of it so I can't get another magnet back to back against it.

I have emailed JTR (speaker manufacturer) directly as well to see if they have any ideas or sell shielded drivers I could replace these with so we'll see if they have any ideas.

Anyone else have any other ideas on how I can get this shielded so I can keep it in the current spot?
 
purbeast0

purbeast0

No Lifer
Sep 13, 2001
53,251
6,101
126
damian101 said:
I think the shielding also needs to be grounded for best effect.
Click to expand...
Well there are ground wires in there from the speakers.

But I mean can you elaborate more than "shield with foil?"

I tried putting foil in there on the side near the monitor and it had zero effect.

I also tried this tonight:


and it did nothing. I got a 6" HVAC cap and taped it on and it made no difference.
 
J

Jimminy

Senior member
May 19, 2020
416
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Wouldn't something like mu-metal be needed to shield magnetic fields?
en.wikipedia.org

Mu-metal - Wikipedia

en.wikipedia.org en.wikipedia.org

I remember some of the old crt oscilloscopes had mu-metal shields around the crt. I never saw a TV or computer monitor with such a crt shield though.
 
damian101

damian101

Senior member
Aug 11, 2020
291
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Maybe normal conductive material don't shield well against low-frequency electromagnetic fields. That would make sense to me.
A mu-metal shield for the CRT might indeed be the solution, if it doesn't already have one.
 
purbeast0

purbeast0

No Lifer
Sep 13, 2001
53,251
6,101
126
Yah I've been pointed to mumetal as well and contacted them. It may be the route I go if I can't find a cheaper solution.
 
sdifox

sdifox

No Lifer
Sep 30, 2005
97,688
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purbeast0 said:
Well there are ground wires in there from the speakers.

But I mean can you elaborate more than "shield with foil?"

I tried putting foil in there on the side near the monitor and it had zero effect.

I also tried this tonight:


and it did nothing. I got a 6" HVAC cap and taped it on and it made no difference.
Click to expand...

Pipe caps are thicker than hvac cap, also they are more likely to be ferromagnetic.


Never mind, the ones in the pixs on that site are hvac caps.

You got a cast iron pot or skillet? Try that first. Just put something non ferromagnetic in between the driver and the cast iron pot/skillet.
 
Last edited:
purbeast0

purbeast0

No Lifer
Sep 13, 2001
53,251
6,101
126
So an update on this, I ended up realizing my one speaker I was trying to shield had 2 of the 3 drivers not making any sound. So I took it apart and I fixed that and now back to the shielding issue. I bought some more steel plates from HD that are thicker and just putting them on the side it seemed to work again. I need to play around with placement though. Ideally I could put them inside the cabinet on the left side, like hang them from nails inside or something.
 
purbeast0

purbeast0

No Lifer
Sep 13, 2001
53,251
6,101
126
So I got this problem like 99% solved.

I ended up getting 2 12x12" 16 gauge steel plates from HD. I noticed if I put them in a certain spot on the left of the cabinet that it pretty made the interference go away completely.

So I decided to put one inside of the cabinet. I did so by taking out one of the monitor mounts, cutting 2 holes into the steel sheet, putting it around the screws for the mount, then putting the mount back in.

gUWrjFR.jpg


Here it is with the mount back on.

JpUzYMW.jpg


I still saw a little bit of distortion so I then decided to put one of the steel plates on the side of the speaker since when I held it up there, the interference went away pretty much 100%.

I decided to sand and spray one side of the sheet matte black so it would blend in pretty nicely. I then got some heavy duty velcro and put it on the speaker and steel sheet. It turned out pretty well and blends in nicely.

fZfHb6W.jpg


You can notice it if you're looking for it, but if you're not, it's hard to notice. Any time I'm playing any games the lights are out down there anyways so you won't notice it.

1eudtkJ.jpg


I say 99% because I'm still seeing a teeny tiny bit of interference when I am in the test blue, red, or green screens, but in an actual game I cannot notice it at all. I may play around with moving the sheet on the speaker around like 1/2" or so and see if it makes any difference too, since it's just velcroed on.
 
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