Shifted magnet

McIntosh/Polk
McIntosh/Polk Posts: 7
edited May 2014 in 2 Channel Audio
Hello: I just bought a pair of Monitor 10 A's. One driver didn't work. So I pulled it out to take a look. The magnet had shifted. Is this a common problem? Don't know if this happened when it was shipped or not. Is replacing the driver the only solution ? Never had this problem with the 7's I've owned since new in 1977. And they survived a couple of hurricanes.
Post edited by McIntosh/Polk on
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  • teekay0007
    teekay0007 Posts: 2,289
    edited May 2014
    Welcome to Club Polk Mc/P!

    The vintage Monitor drivers' magnets are susceptible to shifting and locking up. It most often happens when the speaker cabinets take a jolting blow, like when dropped by a shipping company driver or sorter. Driver replacement is the only SANE solution. There are some threads here that go into the detail of fixing a shifted-magnet driver if you care to give it a shot. However, the task looks to be quite tedious, time consuming and about as fun as a root canal. YMMV!

    Good luck.
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  • F1nut
    F1nut Posts: 50,557
    edited May 2014
    ^This^
    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 t-u-r-d by the clean end."

    President of Club Polk

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  • McIntosh/Polk
    McIntosh/Polk Posts: 7
    edited May 2014
    teekay the root canal and driver repair are out. Lucked up on some replacement drivers last night on ebay. Hope they take care of the problem. Any other quirks I should lookout for with 10's ? And thanks for welcoming me.
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  • pitdogg2
    pitdogg2 Posts: 25,442
    edited May 2014
    McIntosh/Polk wrote: »
    teekay the root canal and driver repair are out. Lucked up on some replacement drivers last night on ebay. Hope they take care of the problem. Any other quirks I should lookout for with 10's ? And thanks for welcoming me.

    make sure you tell the shipper the magnet problem or you could have some more shifted drivers. I always ask them to put paper on the driver paper and then tape that magnet very well and then go around the magnet and most important MAKE SURE THEY CAN'T MOVE in the box in the least. then once I'm satisfied they work I epoxy the magnets. JB weld and others like such.
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  • teekay0007
    teekay0007 Posts: 2,289
    edited May 2014
    McIntosh/Polk wrote: »
    Any other quirks I should lookout for with 10's ? And thanks for welcoming me.

    Some good points from pitdogg2 there - make sure the driver is sent securely so the same thing doesn't happen to the replacement one as did to the original. When you receive it, check it out to make sure it made the trip intact. Then, get some good epoxy - lots of folks around here like JBWeld - and glue the magnets in place (replacement driver and on the other three original drivers) so the same thing doesn't happen down the road with any of them. There's several threads with pics around here that cover the epoxy process. Basically, you want to put a bead of epoxy around the magnets that binds them to the core in the middle so they can't shift.

    Love the Monitor 10s! They are my first - of MANY! - pair of Polk speakers and I still have that original pair I bought new in 1989. After you have some time spent with them, you might want to think about doing some of the mods/upgrades that are extensively documented in many many threads here.

    Enjoy! (TM Coca-Cola Bottling Co.)
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  • deafbykhorns
    deafbykhorns Posts: 150
    edited May 2014
    Is this common with all the mid/bass drivers? Or certain years/models?
    Main System- Scratch built 2A3 , Lightspeed preamp, Technics SP15/Graham/XV1s,Klipschorns w/ALK xovers/Trachorns, Speakercraft MT8(4), Sonos ZP90, Yamaha Aventage for surround
    Office System- Adcom GTP500, Bedini 45/45,Lexicon RT-20,Enlightened Audio DAC, Polk SDA2.3TL, Northcreek Borealis
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  • teekay0007
    teekay0007 Posts: 2,289
    edited May 2014
    deafbykhorns wrote: »
    Is this common with all the mid/bass drivers? Or certain years/models?

    I wouldn't call it "common" by any means, but all vintage mid/bass drivers are susceptible to it happening; no specific years/models moreso than others, but I'd guess that with increased age and "handling" it would get more and more likely. Your best bet is to do the preventative epoxy/JBWeld treatment to each driver.
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  • madmax
    madmax Posts: 12,434
    edited May 2014
    teekay0007 wrote: »
    Your best bet is to do the preventative epoxy/JBWeld treatment to each driver.

    I believe I will do this to mine, hadn't thought of it before. Over the years I've received a few of these drivers with shifted magnets. I'm afraid they will just let loose on their own at some point.
    Vinyl, the final frontier...

    Avantgarde horns, 300b tubes, thats the kinda crap I want... :D
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