Video shielding classic Monitor series

heiney9
heiney9 Posts: 25,217
edited May 2007 in Speakers
It seems like I remember seeing this discussed before but my search comes up with nada. It seems we came up with lead sheets with some kind of stick 'em on the back to line the interior of older Polks to make then sheilded so as not to cause a CRT tube to discolor. Is this possible? Anyone remember the discussion? I think Ken S. was involved somehow.

If not, is there such a product as lead lining that could be put inside the cabinet to sheild the magnetic field enough to use as center channel for an HT rig?

I have an interested party in my single 5b, and he wants to use it as a center to go along with his 10b's. Is there anyway to sheild the drivers if it's going to be close to a CRT?

H9
"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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • nadams
    nadams Posts: 5,877
    edited April 2007
    they're called bucking magnets. Basically the opposite polarity of the original magnet, it sticks itself to the driver and cancels out the magnetic field. You'll need one for the midrange and one for the tweeter.
    Ludicrous gibs!
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  • heiney9
    heiney9 Posts: 25,217
    edited April 2007
    Thanks, Nadams! Do you know if they are expensive and can you get them at Home Depot or Lowes or Rat Shack? I'll pass the info along to my prospective buyer.

    H9
    "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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • nadams
    nadams Posts: 5,877
    edited April 2007
    While I had the right product, it seems I didn't have my facts straight. Do a search for "bucking magnets" on google and you'll find a wealth of information to pass on to the buyer. One thing to be aware of is that when using them, you're altering the magnetic field, which means the operating parameters of the driver will change.
    Ludicrous gibs!
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  • I-SIG
    I-SIG Posts: 2,243
    edited April 2007
    I added bucking magnets to the SDA-1c Studio's I had. Ken didn't seem to think it was a big deal adding them. They were like 8 bucks for the mids and 6 for the tweets. Polk shipped them straight to me. At Ken's suggestion I epoxied them to the drivers.

    They made a huge difference as I had to get the TV within a couple of inches for any interference.

    Wes
    Link: http://polkarmy.com/forums

    Sony 75" Bravia 4K | Polk Audio SDA-SRS's (w/RDO's & Vampire Posts) + SVS PC+ 25-31 | AudioQuest Granite (mids) + BWA Silver (highs) | Cary Audio CAD-200 | Signal Cable Silver Resolution XLR's | Rotel Michi P5 | Signal Cable Silver Resolution XLR's | Cambridge Audio azur 840C--Wadia 170i + iPod jammed w/ lossless audio--Oppo 970 | Pure|AV PF31d
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  • Sumbrada77
    Sumbrada77 Posts: 37
    edited April 2007
    Hey Heiney9 this is Sumbrada77 the interested party of your 5b. Reading this
    set i di a little checking on sheilding. Maybe these to links can help others as it did me. More time to play.
    http://www.hometheaterforum.com/htf/archive/index.php/t-18575.html
    http://forums.audioholics.com/forums/showthread.php?t=21091
    http://www.andrewrondeau.com/Voight%20Pipes/shielding.html
    CARPE CEREVISI!!
    A Wise man, Keeps his Friends close, but keeps his
    Enemies Closer !!

    Yamaha RX-V659 A/V receiver, Maganox CDP482 CD,
    Pansonic DVD F85, Marantz 6300 TT w/Apature KOCE
    Polk 10s (mains), M&K 3B (backs), Polk 5b Center
    HSU Research VTF-2 Mk1 subwoofer
    DIY twisted speaker cable
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  • heiney9
    heiney9 Posts: 25,217
    edited April 2007
    So did you get your questions answered? Thanks for the links. Is the single 5b going to work out for you?

    H9
    "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 Labs XA25 | EE Avant Pre | EE Mini Max Supreme DAC | MIT Shotgun S1 | Pangea AC14SE MKII | Legend L600 | BlueSound Node 3 - Tubes add soul!
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  • Polk65
    Polk65 Posts: 1,405
    edited May 2007
    It depends on the height of the speakers and the CRT TV. Sometimes you can succeed by just raising the TV a few inches. I slapped some bucking magnets last year on the mid-woofers closest to my TV and can move the speakers within 12" of the TV with no visible effect.

    Last week I tried the air duct cap mentioned in link #3 above. I tried it alone and with magnets but it had no effect. If I find some cheap mu-metal somewhere I may give that a try but for now I am done with this.
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