Speakers causing discolouration on monitor

[headkaze]

The speakers in my arcade cab are car speaker stereo speakers rigged through a Logitech amp. As you can see by the attached image the speakers are relatively close to the 21" monitor. Too close it seems.

For a long time it's bugged me having discolouration on the monitor caused by interference from the speakers. It's a real kill joy to see bright colours like red and blue going strange colours towards the edges of the monitor near where the speakers are mounted. I've tried a few things to rectify this.

1. First thing I tried was to buy a digaussing wand. These things are actually really handy, but they only get rid of the effect of a magnetic field temporarily. If you have a magnetic field nearby the problem will eventually return. I got all excited when the problem seemed to disappear but it came back.

2. I read somewhere to try aluminium foil. So I got a whole bunch of it folding it several times then wrapped it around the back of the speakers. Didn't work.

3. Now from reading this article it inspired me to try something new. He uses an air-duct pipe cap to cover the back of the speakers' magnets. He says the material must be magnetic. Aluminium foil isn't magnetic.

So I was in the kitchen today and noticed a large can of tomatoes (I love cooking spagetti bolognaise) and wondered if they were magnetic. So I got a magnet off the fridge and sure enough it was. So before I started cutting up the can of tomatoes I took a look in the shed and sure enough found two old cans of tomotoes. I cut off the end of the cans and placed them over the aluminium foil. I thought I may as well use the foil to hold on the can rather than tape it there.

Next I set the desktop colour to bright red so I could see the effect of the magnets on the screen. Ran the degauss wand over it to remove the effect. Now I just have to wait and see if it comes back! Stay tuned

[Creek]

Hehe, nice. Who would have thought.

[iano]

You could use bucking magnets. They're available from www.partsexpress.com .You glue them to your speaker magnets with the opposite magnetic poles facing each other. They'll repel each other which is why you'll have to use industrial strength glue. The idea is that the bucking magnet will cancel out the effects of the magnetic field of the speaker magnet so you don't get any discoloration on your monitor. They're pretty cheap. I read this in the Saint's book Project Arcade.

[The G-Man]

Iano is right, bucking magnets is the way to go. They will shield your speakers from damaging you screen and will cause no deterioration in your sound quality. partsexpress.com has reasonably prices for these.

[headkaze]

I have heard of bucking magnets and I have considered them. I even asked someone on BYOAC to order some for me.

I live in Australia, and to quote partsexpress website regarding international orders

$50 minimum order, not including shipping charges, is required for all international orders (does not apply to Canada).

They may be cheap, but I don't need $50 worth of then

I'll see if the tin cans work, if not I will have to find someone willing to order and send them to me.

[Brian Hoffman]

I have heard of bucking magnets and I have considered them. I even asked someone on BYOAC to order some for me.

I live in Australia, and to quote partsexpress website regarding international orders

They may be cheap, but I don't need $50 worth of then

I'll see if the tin cans work, if not I will have to find someone willing to order and send them to me.

Aluminum might work better as a shield as it isnt magnetic.

[headkaze]

Aluminum might work better as a shield as it isnt magnetic.

Bucking magnets are magnets that is how they cancel out the magnetic field causing the discolouration. I believe to shield you have to have a metal that is magnetic. If you read that link I gave on making one from a pipe cap he says make sure the metal is magnetic or it won't work.

I think it's more about cancelling out the magnetic field than shielding. So magnets are probably the only way to do that.

[LB11]

If the tin cans dont work, why not find a local garage sale or something. Im sure you could get a used desktop stereo system with shielded speakers for very cheap.

[SpyDIRmaN]

I have heard of bucking magnets and I have considered them. I even asked someone on BYOAC to order some for me.

I live in Australia, and to quote partsexpress website regarding international orders

They may be cheap, but I don't need $50 worth of then

I'll see if the tin cans work, if not I will have to find someone willing to order and send them to me.

I live in Australia as well, but I'm originally from California (only been out here for a couple of years).

My family all still live in the states, and I have them mail me stuff fairly often. If your can idea doesn't work, I could always order these magnets online, send them to my sister and have her mail them out this way (straight to you would probably be quicker).

If it's not too expensive, I'd just consider it my donation for your CPViewer work. otherwise I've got paypal and we could work out the difference or something.

Just thought I'd throw that out there. I've had my own troubles trying to get things from the US out here. I miss good mexican food and tequila, if only they could send that

[bkenobi]

On partsexpress these are only $0.75 - $1.83 USD each. I don't know the conversion to Australian currency, but I know that for under $10 USD shipped you can't even find a degaussing wand! I've recently noticed this problem with my cabinet, so I may look into it. The speakers were from the original cabinet so I assumed they would be shielded, but apparently not. I also have another set which I'll have to try, but I'm guessing it will be the same. Either way, this is definitely a cheap fix if it works (perhaps cheaper than the tomatoes!

[headkaze]

Thanks SpyDIRmaN I really appreciate the offer but it looks like the tin cans have worked! Still no discolouration since I put them in last night

[bkenobi]

I ended up swapping my speakers with a spare set I salvaged from another machine. Turned out that the original ones had no shielding but the new ones were. MUCH better! Thanks for starting this topic HK!

[headkaze]

I live in Australia as well, but I'm originally from California (only been out here for a couple of years).

My family all still live in the states, and I have them mail me stuff fairly often. If your can idea doesn't work, I could always order these magnets online, send them to my sister and have her mail them out this way (straight to you would probably be quicker).

If it's not too expensive, I'd just consider it my donation for your CPViewer work. otherwise I've got paypal and we could work out the difference or something.

Just thought I'd throw that out there. I've had my own troubles trying to get things from the US out here. I miss good mexican food and tequila, if only they could send that

Mate those tin cans didn't work, the discouration came back with a vengance. If you can ask your family if they can order some of those bucking magnets for me I'd really appreciate it. I don't mind paying for any costs/postage etc. I just can't stand this effect on my monitor anymore, It's driving me nuts!

I measured the magnet on the back of the speaker and its ~7cm in diameter if that helps. Let me know if you can

[SpyDIRmaN]

Mate those tin cans didn't work, the discouration came back with a vengance. If you can ask your family if they can order some of those bucking magnets for me I'd really appreciate it. I don't mind paying for any costs/postage etc. I just can't stand this effect on my monitor anymore, It's driving me nuts!

I measured the magnet on the back of the speaker and its ~7cm in diameter if that helps. Let me know if you can

Yeah, took a quick look at the PartsExpress site, and they look pretty cheap. I can try and get ahold of my sister tomorrow and see if she won't mind watching for them in the mail, and forwarding them this way.

I'm not sure exactly which ones you will need though. I know nothing about bucking magnets, and I'd hate to order the wrong ones. If you wanna take a look, and work out which ones you think you need. I'll take care of the rest mate.

-Brian (SpyDIRmaN)

[headkaze]

Yeah, took a quick look at the PartsExpress site, and they look pretty cheap. I can try and get ahold of my sister tomorrow and see if she won't mind watching for them in the mail, and forwarding them this way.

I'm not sure exactly which ones you will need though. I know nothing about bucking magnets, and I'd hate to order the wrong ones. If you wanna take a look, and work out which ones you think you need. I'll take care of the rest mate.

-Brian (SpyDIRmaN)

Cheers mate, that is great to hear

I had a look at the magnets available at parts express and they state on the website that "As a general rule, the bucking magnet should be approximately 1/2 to 2/3 the size of the driver magnet".

I measured my speaker magnets and they are around 7 cm in diameter and the smallest bucking magnet they have on their website is the "Ferrite Bucking Magnet 3 oz. 60mm x 25mm x 8mm". So I guess two of them would be the way to go, but they are probably a little big. Maybe I should also try two of the "Ferrite Bucking Magnet 3.5 oz. 60mm x 32mm x 10mm" as they are so cheap (shipping will likely cost more than the magnets).

http://www.partsexpress.com/pe/showdetl.cf...tnumber=329-207

http://www.partsexpress.com/pe/showdetl.cf...tnumber=329-208

I'll be happy to give either of those types a try. Thanks again mate your a champ

[SpyDIRmaN]

Cheers mate, that is great to hear

I had a look at the magnets available at parts express and they state on the website that "As a general rule, the bucking magnet should be approximately 1/2 to 2/3 the size of the driver magnet".

I measured my speaker magnets and they are around 7 cm in diameter and the smallest bucking magnet they have on their website is the "Ferrite Bucking Magnet 3 oz. 60mm x 25mm x 8mm". So I guess two of them would be the way to go, but they are probably a little big. Maybe I should also try two of the "Ferrite Bucking Magnet 3.5 oz. 60mm x 32mm x 10mm" as they are so cheap (shipping will likely cost more than the magnets).

http://www.partsexpress.com/pe/showdetl.cf...tnumber=329-207

http://www.partsexpress.com/pe/showdetl.cf...tnumber=329-208

I'll be happy to give either of those types a try. Thanks again mate your a champ

Hey mate, just got back online (been having issues with my internet)... I'll try and get hold of my sister tonight, and see if she won't mind helping us out. I'll post back here as soon as I know...

[headkaze]

Hey mate, just got back online (been having issues with my internet)... I'll try and get hold of my sister tonight, and see if she won't mind helping us out. I'll post back here as soon as I know...

Cheers mate, fingers crossed

[bkenobi]

Wouldn't it be easier at some point to just order new speakers from happs or BobRoberts or just buy some cheap speakers from a local car audio shop? I hope those magnets work, but speakers for an arcade aren't exactly put under high demand even if you are playing music...

[SpyDIRmaN]

Cheers mate, fingers crossed

Good news, she says she'll do it. Had to get hold of her on myspace (lol) as I kept missing her on the phone (damn time difference). With any luck I should be able to order them tomorrow, just need to get her address again (forgot to ask) as I haven't sent her anything in awhile

Hopefully the turn around time on all this won't be toooo long. I know how much it sucks when those little problems pop up. I'm a perfectionist to a point, and then I just say "stuff it" , and try something else...

fingers crossed this will fix your problem.

[gorgeousjorge]

I`m also having the same prob,i didn`t know what it was until i saw this thread.

I have a lifetech stereo desktop speakers,in the manual they say it is shielded but my monitor has strange colours on the top;it`s really a pain in the #$%.

Just as a side question:does this magnetic issue only effects crt`s?

Or should i be councerned about lcd`s also?

Best regards mates

[iano]

I`m also having the same prob,i didn`t know what it was until i saw this thread.

I have a lifetech stereo desktop speakers,in the manual they say it is shielded but my monitor has strange colours on the top;it`s really a pain in the #$%.

Just as a side question:does this magnetic issue only effects crt`s?

Or should i be councerned about lcd`s also?

Best regards mates

I think the problem only affects crt monitors.

[headkaze]

I took the bucking magnets off my speakers yesterday as the discolouration is clearly creeping back and it was even starting to appear at the bottom of the monitor. Now I guess I will need to either buy an LCD monitor or get some different speakers

[bkenobi]

The discoloration is caused by the magnetic field changing the path of the electrons inside the tube. Basically, the gun at the back of the CRT emits electrons based on the source signal. When the magnets interfere with their trajectory, you can see the field on the CRT. This does not affect other types of displays.

However, it is possible the magnets could cause other types of issues with other displays (interfere with the actual electronics). I have never seen that happen or read any accounts of it either.

If you want to read up on it a little more, this seems to be a pretty good article.

[Inigo Montoya]

I was having this problem. I ordered bucking magnets from partsexpress and it did help the problem ALOT. Just a hint of discoloration in one corner after i installed them. I found a narrow piece of steel about as wide as the monitor and attached it at about a 90 degree angle in relation to the speakers. This removed all trace of discoloration after degaussing. You must use ferrous metal for sheilding.