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  1. #1

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    Default Vintage speakers = NON magnetically shielded...

    Good evening all;
    I am relocating my living room electronics. I moved away the large entertainment unit that I used for many years as it really looked passť and was never adapted for optimum sound but rather adapted to accomodate my young family.

    I have changed the entertainment unit for 2 small tower cabinets that somewhat matches the wood grain of my vintage speakers and furthermore puts them at hear level.

    The area where I MUST set the electronics has somewhat limited space (80 inches) and must fit my 27 inches CRT Trinitron TV (center) and the 2 small tower cabinets (1 on each side of the TV) which are met to be used as stand for each of the vintage speakers along as storage for the driving electronics. The Tower cabinets are 19 inches wide while the speaker cabinets are 17 inches wide and contain 15 inches NON magnetically shielded drivers, 5.5 inches NON magnetically shileded mid driver along with 2 1 inches tweeters.

    My problem, due to the space restraint and the power of the magnetic field generated by the speaker drivers, I suspect this will cause some issues (distortion) with the picture tube of my Sony CRT (In fact, I did a quick test and could see some color distortion).

    My question, is anyone aware of some form of DIY modification in order to somehow shield the magnetic field from those speakers? Any suggestions or alternatives?

    I have other speakers (modern, smaller and shielded) which I could use but while those vintage are not high end they are full of memories along with being in mint condition. I always loved the warm sound coming out of them. This small living room (10' x 12' Wide).

    Any suggestions that may help with my magnetic field issue would be greatly aprreciated.

    Cheers!
    TK

  2. #2

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    Get some shielding magnets from parts-express if you have any problems with the tubed TV.
    They are easily glued in place with some epoxy.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  3. #3

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    Quote Originally Posted by ben62670 View Post
    Get some shielding magnets from parts-express if you have any problems with the tubed TV.
    They are easily glued in place with some epoxy.
    Thanks Ben however, I've search for the above on their site and it doesn't seem to be available any longer. I'll try to google this...

    Cheers!
    TK

  4. #4

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    Last edited by ben62670; 03-23-2010 at 11:41 PM.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  5. #5

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    Sometimes called "horseshoe" or "Bucking" magnets.
    Try simulating your set up as close as possible and determine IF magnetic interferrence will actually be an issue.
    A matter of an inch may be enough clearance.

  6. #6

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    Get some VS-25s. ;)
    I don't read the newsssspaperssss because dey aaaallllllllll...... have ugly print.

  7. #7

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    Get a plasma or led tv
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30; Eastern Electric Mini Max; Adcom GDA600; MIT S3/Z Pc; SDA 1C; Squeezebox; Tubes add soul!

  8. #8

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    Exactly how close are the speakers going to be to the tube ?

    I really doubt you will have a problem. My 1Cs sit very close to my CRTRP and I have no issues.
    Speakers: SDA-1C (most all the goodies)
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  9. #9

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    Quote Originally Posted by heiney9 View Post
    Get a plasma or led tv
    Humm, I sure tought about this, very tempting but;

    1. I use a PJ in the basement HT for movies and...
    2. Both Living room and bedroom TV's are Sony ( Trinitron & Wega) which are in great shape (perfect condition) and it would be a shame to let them go.
    3. The living room is my chosen area to keep alive my vintage gear and Plasma and-or LCD might not cut it with this decor.

    Quote Originally Posted by thsmith View Post
    Exactly how close are the speakers going to be to the tube ?

    I really doubt you will have a problem. My 1Cs sit very close to my CRTRP and I have no issues.
    I did some checking-testing, I positioned the speaker on the tower furniture as far as possible from the TV side which is aprroximately 6 inches and I can see color and picture distortion both the bottom and top of the CRT. I then proceeded to move the speakers farther away from the TV until the distortion disappeared on the tube and this started to occur at approximately 15 inches. This kind of make sense, ideally I would say between 2 - 3 feet away from a CRT would be safe in the case of NON magnetically shielded speakers.

    I've done some search after Ben's response and another option to shield the magnet(s) was mentioned on many sites. Here is an option, has anyone tried this? Any opinions?

    http://www.lessemf.com/mag-shld.html
    http://andrewrondeau.com/Voight%20Pipes/shielding.html
    http://www.trifield.com/EMF_shielding.htm
    http://stason.org/TULARC/entertainme...-near-a-T.html

    Cheers!
    TK

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    I hear ya TK, I still have a perfectly nice Mits crt TV, but I took the plunge on a plasma and I didn't know what I was missing-lol

    Polk used to sell "bucking" magnets you can put on the driver magnets. Not sure if they still do. The magnets do alter the drivers a bit. You could call Polk CS and see if they are still avail.
    "Appreciation of audio is a completely subjective human experience. Measurements can provide a measure of insight, but are no substitute for human judgment. Why are we looking to reduce a subjective experience to objective criteria anyway? The subtleties of music and audio reproduction are for those who appreciate it. Differentiation by numbers is for those who do not".--Nelson Pass

    Pass Aleph 30; Eastern Electric Mini Max; Adcom GDA600; MIT S3/Z Pc; SDA 1C; Squeezebox; Tubes add soul!

  11. #11

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    Quote Originally Posted by heiney9 View Post
    I hear ya TK, I still have a perfectly nice Mits crt TV, but I took the plunge on a plasma and I didn't know what I was missing-lol

    Polk used to sell "bucking" magnets you can put on the driver magnets. Not sure if they still do. The magnets do alter the drivers a bit. You could call Polk CS and see if they are still avail.
    Thanks, I'll check if Polk still carries them. You are right about altering the driver, I also read about that after searching for more info on the subject. As far as LCD and-or Plasma, if I were to replace one of the Sony, I would ratter start with the bedroom for space saving. By the way, you would be surprised how good a digital signal interfaced to a CRT looks. Agreed it is not 1080p but still quite an improvement over the usual 480i signal.

    Cheers!
    TK

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    TK, I don't what vintage speaker you are trying to use, but the MW6504's are a shielded version of the MW6502. Ben (concealer404) is somewhat right, as the VS-25's have them.
    Polk CS might still have them, if they don't have any bucking magnets available.

  13. #13

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    Quote Originally Posted by kcoc321 View Post
    TK, I don't what vintage speaker you are trying to use, but the MW6504's are a shielded version of the MW6502. Ben (concealer404) is somewhat right, as the VS-25's have them.
    Polk CS might still have them, if they don't have any bucking magnets available.
    I have other speakers (modern, smaller and shielded) which I could use but while those vintage are not high end they are full of memories along with being in mint condition. I always loved the warm sound coming out of them. This small living room (10' x 12' Wide).
    Sorry, I guess I was not clear enough when describing my vintage speakers. We are NOT talking about any of my POLK speakers (which are ALL magnetically shielded) but I am ratter talking about my AKAI SW-177 vintage speakers (http://www.vintage-audio.com.ua/en/cat/232/857.html; http://www.polkaudio.com/forums/show...highlight=akai)

    Cheers!
    TK

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    Quote Originally Posted by TECHNOKID View Post
    Sorry, I guess I was not clear enough when describing my vintage speakers. We are NOT talking about any of my POLK speakers (which are ALL magnetically shielded) but I am ratter talking about my AKAI SW-177 vintage speakers (http://www.vintage-audio.com.ua/en/cat/232/857.html; http://www.polkaudio.com/forums/show...highlight=akai)

    Cheers!
    TK
    AH, alrighty...then you do need the aftermarket bucking magnets

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    I'm pretty sure our friends north of the border spell it as we do, rather ;)
    'Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

  16. #16

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    Wink reply;mag shielding made easy.

    Quote Originally Posted by TECHNOKID View Post
    Good evening all;
    I am relocating my living room electronics. I moved away the large entertainment unit that I used for many years as it really looked passť and was never adapted for optimum sound but rather adapted to accomodate my young family.

    I have changed the entertainment unit for 2 small tower cabinets that somewhat matches the wood grain of my vintage speakers and furthermore puts them at hear level.

    The area where I MUST set the electronics has somewhat limited space (80 inches) and must fit my 27 inches CRT Trinitron TV (center) and the 2 small tower cabinets (1 on each side of the TV) which are met to be used as stand for each of the vintage speakers along as storage for the driving electronics. The Tower cabinets are 19 inches wide while the speaker cabinets are 17 inches wide and contain 15 inches NON magnetically shielded drivers, 5.5 inches NON magnetically shileded mid driver along with 2 1 inches tweeters.

    My problem, due to the space restraint and the power of the magnetic field generated by the speaker drivers, I suspect this will cause some issues (distortion) with the picture tube of my Sony CRT (In fact, I did a quick test and could see some color distortion).

    My question, is anyone aware of some form of DIY modification in order to somehow shield the magnetic field from those speakers? Any suggestions or alternatives?

    I have other speakers (modern, smaller and shielded) which I could use but while those vintage are not high end they are full of memories along with being in mint condition. I always loved the warm sound coming out of them. This small living room (10' x 12' Wide).

    Any suggestions that may help with my magnetic field issue would be greatly aprreciated.

    Cheers!
    TK
    Go to your nearest Sign making outlet or print shop (business cards )......or even a cheap dollar store or china importer, and buy the mag strisp commonly used on refrig reminders.
    Use the strips (2) glued together black side facing ea. other. staple them inside the cabinet nearest the speaker mags.
    do only the side that will be adjacnt to the TV mon.
    for added resist....place a cheap steel (1/64th thickness) plate onto the inner wall surface where the mags allign and mount it so that there is 3 in. below and above the mag. diam....the plates are scrap ...you can even buy plates at home depot....you can even use studd connector pieces holes and all.
    This requires removing usually the large speaker for access to inner surface of spkr. you should be able to approach close to 4 inches before you begin to see distortion.


    .

  17. #17

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    Ummmm, no. Besides messing up cabinet resonance, you're not even canceling the magnetic field created by the driver's magnet doing what you describe.

    Bucking magnets are cheap and very effective.
    'Political Correctness'.........defined

    "A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end."

  18. #18

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    Quote Originally Posted by raybertrand View Post
    Go to your nearest Sign making outlet or print shop (business cards )......or even a cheap dollar store or china importer, and buy the mag strisp commonly used on refrig reminders.
    Use the strips (2) glued together black side facing ea. other. staple them inside the cabinet nearest the speaker mags.
    do only the side that will be adjacnt to the TV mon.
    for added resist....place a cheap steel (1/64th thickness) plate onto the inner wall surface where the mags allign and mount it so that there is 3 in. below and above the mag. diam....the plates are scrap ...you can even buy plates at home depot....you can even use studd connector pieces holes and all.
    This requires removing usually the large speaker for access to inner surface of spkr. you should be able to approach close to 4 inches before you begin to see distortion.


    .
    What you're describing wouldn't really solve the problem the right way. That also sounds like much more work than is necessary. As Jesse mentioned above, this would also be changing the cabinet resonances, along with not even cancelling the magnetic field.

    Bucking magnets work very well, are very cheap, and take all of 20 seconds to install. I picked up some bucking magnets a while back for a pair of circa-1992 Polk Mini Monitors. I was using one of them as a center channel for a while, and it wasn't magnetically shielded. I put the bucking magnet on, and it solved my problem instantly.

    Others have mentioned that the bucking magnets can affect the sound...but I can't say that I ever noticed any audible differences.
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  19. #19

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    Great news !
    I wanted to sheild a pair of older S4 , polk still carries the magnet for the mw7000 6.5" driver but not for the tweeter but I found one at madisound ( I know its mentioned above)
    but I got the magnet for 50 cents !!!
    I just tried it and it works great !!

  20. #20

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    Quote Originally Posted by 20hz View Post
    Great news !
    I wanted to sheild a pair of older S4 , polk still carries the magnet for the mw7000 6.5" driver but not for the tweeter but I found one at madisound ( I know its mentioned above)
    but I got the magnet for 50 cents !!!
    I just tried it and it works great !!
    Odd, I communicated with Polk and was told they dodn't carry them anymore. Yes madisound carries them but were back order when I first checked. Nice to heaR THAT THEY ARE BACK.

    Cheers!
    TK

  21. #21

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    Yes polk no longer has the magnet for the tweeter sl5000 but madisound.com has item # 707517 they are 50 cents each (plus you get a feee catalogue) .
    So I bought polks magnet for the mw7000 and madisounds #707517 for the tweeter .
    This gives me everything for the S4 .
    I got All four magnets this month .

  22. #22

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    Congrats!
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

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