Remember to epoxy your woofer magnets!

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  • lawdogg
    lawdogg Posts: 470
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    Epoxying magnets is FUN!

    IMG_20160219_204638397_HDR.jpg
    <3 my 3.1TLs

    I will fix your shifted magnets for free. :)
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  • xschop
    xschop Posts: 5,766
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    o1w61papazgf.png
    Don't take experimental gene therapies from known eugenicists.
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  • xschop
    xschop Posts: 5,766
    edited March 2016
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    The 5.75" dimension needs to match the hand tool guide OD as a slip-fit tolerance. The extra length I put on the cylinder allows the guide tool to seat fully and center before magnet sets. The 1/2" diameter thru-hole needs to be there to relieve the internal pressure or the cone will blow-out.axoihmgc4okg.png
    Don't take experimental gene therapies from known eugenicists.
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  • RandyCroissant
    RandyCroissant Posts: 475
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    I think you are on the right track with this, question what part will center the pole piece?
    Yamaha RXA1030, Yamaha CD-S2100, Yamaha AS-2200, Bluesound node 2i
    Polk SDA2btl highly modded
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    Wish list SVS sub

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  • westmassguy
    westmassguy Posts: 6,850
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    Be sure to observe proper magnet polarity when re-assembling, otherwise the woofer will be out of phase.
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
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    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer

    dhsspeakerservice.com/
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  • xschop
    xschop Posts: 5,766
    edited March 2016
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    Randy, I believe the small hole in the back plate is the factory lathe turn center which would be concentric to the guidepost. It's 0.375 diameter on all ones I measured. It tapers at @ 0.200 depth so 0.175" length is the guide pin on above hand tool drawing. I would make the hand tool out of 4130 or 1018 steel so the magnet and back plate self stick to it after they are glued in first step.
    Don't take experimental gene therapies from known eugenicists.
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  • RandyCroissant
    RandyCroissant Posts: 475
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    Ok I see what you mean, that should work.
    Yamaha RXA1030, Yamaha CD-S2100, Yamaha AS-2200, Bluesound node 2i
    Polk SDA2btl highly modded
    Polk SDA 1C modded
    Polk CS350 LS x2
    Kimber 8TC
    Sony 55" Bravia
    Wish list SVS sub

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  • xschop
    xschop Posts: 5,766
    edited March 2016
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    WMG, which way is N & S in relation to front and back plates?

    Is it not also imperative that the magnet ID be set 100% concentric to the guide post OD or the voice coil will have an off-axis pull when current is run?
    Don't take experimental gene therapies from known eugenicists.
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  • westmassguy
    westmassguy Posts: 6,850
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    I doubt there are markings on the magnets, just hold one over an unmolested Polk woofer. If it attracts, its positioned right, if it repels, it's reversed.
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer

    dhsspeakerservice.com/
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  • RandyCroissant
    RandyCroissant Posts: 475
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    Dave is there anything you don't know!!
    Yamaha RXA1030, Yamaha CD-S2100, Yamaha AS-2200, Bluesound node 2i
    Polk SDA2btl highly modded
    Polk SDA 1C modded
    Polk CS350 LS x2
    Kimber 8TC
    Sony 55" Bravia
    Wish list SVS sub

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  • Nightfall
    Nightfall Posts: 10,083
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    RandyCroissant wrote: »
    Dave is there anything you don't know!!

    The meaning of life? :p
    afterburnt wrote: »
    They didn't speak a word of English, they were from South Carolina.

    Village Idiot of Club Polk
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  • ken brydson
    ken brydson Posts: 9,089
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    RandyCroissant wrote: »
    Dave is there anything you don't know!!
    RandyCroissant wrote: »
    Dave is there anything you don't know!!

    Women?
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  • westmassguy
    westmassguy Posts: 6,850
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    ken brydson wrote: »
    RandyCroissant wrote: »
    Dave is there anything you don't know!!
    RandyCroissant wrote: »
    Dave is there anything you don't know!!

    Women?
    Once you fully understand them, you're on the wrong side of the lawn.
    Home Theater/2 Channel:
    Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
    Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
    Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
    Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
    Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer

    dhsspeakerservice.com/
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  • voltz
    voltz Posts: 5,384
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    Nightfall wrote: »
    RandyCroissant wrote: »
    Dave is there anything you don't know!!

    The meaning of life? :p

    thats easy its 42.
    2 ch- Polk CRS+ * Vincent SA-31MK Preamp * Vincent Sp-331 Amp * Marantz SA8005 SACD * Project Xperience Classic TT * Sumiko Blue Point #2 MC cartridge

    HT - Polk 703's * NAD T-758 * Adcom 5503 * Oppo 103 * Samsung 60" series 8 LCD
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  • boston1450
    boston1450 Posts: 7,758
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    All that & it all leads up to
    42
    Randy-Maine
    2ch-RTA15tl crossover upgrade
    by David WMG
    Yamaha cr1000 cr2040
    HT-Yamaha Parasound Acurus
    MIT BJC Cs1000p Polk Rotation
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  • Gunther16
    Gunther16 Posts: 243
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    Dave is the speaker god, all seeing, all knowing. LOL
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  • Sqeek
    Sqeek Posts: 2
    edited May 2021
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    Thanks for having me my first post hear

    I had been putting this off for some time now but after reading about others nightmares i decided to take on the task B)

    I just got through with applying the power grab to my MW6502 buy the time i got good at spreading the power grab it was all over with lol

    I used this pushed inside to power grab tube to do the magnet base to the speaker basket it's simply one of the brushes you get with a re-foam kit with the bristles removed it worked perfect ! Ijust went ahead and used it for all the mating surfaces. b6083w2fd5wu.jpg

    she may not be the prettiest girl in the room but she will do lol ;)

    Next up is to buy the new tweeter upgrades

    z240jhnirnb8.jpg
    w2urqqgiesnf.jpggk93d0gjbv7e.jpg

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  • audioluvr
    audioluvr Posts: 6,055
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    Nice work! Welcome to Club Polk.
    Gustard X26 Pro DAC
    Belles 21A Pre Upgraded with Mundorf Supremes
    B&K M200 Sonata monoblocks refreshed and upgraded
    Polk SDA 1C's modded / 1000Va Dreadnaught
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    Harman Kardon T65C w/Grado Gold. (Don't laugh. It sounds great!)

    There is about a 5% genetic difference between apes and men …but that difference is the difference between throwing your own poo when you are annoyed …and Einstein, Shakespeare and Miss January. by Dr. Sardonicus
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  • Gardenstater
    Gardenstater Posts: 4,892
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    Yes nice job and that will give you some peace of mind. For future reference, you don't need to glue between the basket and the pole piece plate nearest the cone. That must be spotwelded or swaged and not glued.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
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    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • Sqeek
    Sqeek Posts: 2
    edited May 2021
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    Thanks' Guys i appreciate your feedback and kind words

    Ok Thank you Gardenstater thats great information
    Gardenstater wrote: »
    For future reference, you don't need to glue between the basket and the pole piece plate nearest the cone. That must be spot welded or swaged and not glued.

    Thought i would throw this little tib bit in for laughs the magnets didn't come lose but the speaker sticker that is usually on the back of the drivers was lying in the bottom of the Monitor 7 cabs i glued them back on also B):p

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  • Gardenstater
    Gardenstater Posts: 4,892
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    That's good. Just like the tags on pillows and so forth, you can go to prison for having one of those labels off.
    George / NJ

    Polk 7B main speakers, std. mods+ (1979, orig owner)
    Martin Logan Dynamo sub w/6ft 14awg Power Cord
    Onkyo A-8017 integrated
    Logitech Squeezebox Touch Streamer w/EDO applet
    iFi nano iDSD DAC
    iPurifier3
    iDefender w/ iPower PS
    Custom Steve Wilson 1m UPOCC Interconnect
    iFi Mercury 0.5m OFHC continuous cast copper USB cable
    Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
    Custom Vibration Isolation Speaker Stands and Sub Platform
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  • odcics2
    odcics2 Posts: 395
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    I use a 30hz signal while re-foaming woofers to absolutely center the voice coil without removing the dust cap.
    Would that help in centering the magnet to prevent rub?
    If you were off a little, you'd hear it!
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  • Schurkey
    Schurkey Posts: 2,125
    edited May 2021
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    odcics2 wrote: »
    I use a 30hz signal while re-foaming woofers to absolutely center the voice coil without removing the dust cap.
    Would that help in centering the magnet to prevent rub?
    If you were off a little, you'd hear it!
    No, it does not help to actually center the magnet. It will let you know that things aren't right, though, so you can take action to correct what's wrong.

    Realistically, the MAGNET does not have to be perfectly centered, but the pole piece does.

    If you're applying epoxy on a speaker driver that hasn't already come apart, this isn't a concern. The factory alignment hasn't changed. If the pole piece or magnet has already shifted, though, you're going to have to "fix" the alignment and secure the pieces with some other adhesive BEFORE you apply the epoxy.

    When it was me, I cleaned the magnet and pole piece, secured the magnet to the basket with a generic equivalent to Loctite 271 high-strength anaerobic thread locker, then aligned the pole piece and secured it to the magnet with the same stuff. THEN the epoxy after the Loctite has cured. And yes, I was playing music through the speaker as I centered the pole piece as an indicator of alignment. There is not a lot of time to get the pole piece aligned before the anaerobic adhesive sets up. Work fast.
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  • odcics2
    odcics2 Posts: 395
    edited May 2021
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    I'd center the magnet and pole piece to the voice coil. No good reason to not do it...
    Playing music is the same as using a 30hz signal. So, you do agree with my method!
    ;)
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  • lawdogg
    lawdogg Posts: 470
    edited June 2021
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    No. I would absolutely not play a test tone while re-centering the pole piece. Re-centering the pole piece is much different than re-foaming. While re-centering the pole piece, it will have a tendency to initially snap to one side and lock the voice coil in place as you get it started. I would NOT want the voice coil trying to move as I'm doing this.
    <3 my 3.1TLs

    I will fix your shifted magnets for free. :)
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  • Schurkey
    Schurkey Posts: 2,125
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    lawdogg wrote: »
    No. I would absolutely not play a test tone while re-centering the pole piece. Re-centering the pole piece is much different than re-foaming. While re-centering the pole piece, it will have a tendency to initially snap to one side and lock the voice coil in place as you get it started. I would NOT want the voice coil trying to move as I'm doing this.
    That's why I used a fixture. Pole piece does not "snap" anywhere because it's stabilized by the fixture.
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  • mhardy6647
    mhardy6647 Posts: 35,526
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    tbthw1i10r6r.png
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  • lawdogg
    lawdogg Posts: 470
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    Schurkey wrote: »
    That's why I used a fixture. Pole piece does not "snap" anywhere because it's stabilized by the fixture.

    That's great - how did you make it? How does it work?
    <3 my 3.1TLs

    I will fix your shifted magnets for free. :)
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  • Schurkey
    Schurkey Posts: 2,125
    edited June 2021
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    lawdogg wrote: »
    Schurkey wrote: »
    That's why I used a fixture. Pole piece does not "snap" anywhere because it's stabilized by the fixture.

    That's great - how did you make it? How does it work?
    I shamelessly stole the idea from Saftgeek.
    https://forum.polkaudio.com/discussion/135716/lets-try-to-fix-a-mw6511-damaged-in-shipping/p1

    I can't post photos. Here's links.
    http://hbassociates.us/Polk_Magnet_01.jpg

    http://hbassociates.us/Polk_Magnet_02.jpg

    http://hbassociates.us/Polk_Magnet_03.jpg

    http://hbassociates.us/Polk_Magnet_04.jpg

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  • pitdogg2
    pitdogg2 Posts: 27,790
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    Schurkey wrote: »
    lawdogg wrote: »
    Schurkey wrote: »
    That's why I used a fixture. Pole piece does not "snap" anywhere because it's stabilized by the fixture.

    That's great - how did you make it? How does it work?
    I shamelessly stole the idea from Saftgeek.
    https://forum.polkaudio.com/discussion/135716/lets-try-to-fix-a-mw6511-damaged-in-shipping/p1

    I can't post photos. Here's links.
    http://hbassociates.us/Polk_Magnet_01.jpg

    http://hbassociates.us/Polk_Magnet_02.jpg

    http://hbassociates.us/Polk_Magnet_03.jpg

    http://hbassociates.us/Polk_Magnet_04.jpg

    Gosh that was a good link !! Fun time we had back then. So many folks who no longer stop and say Hi.
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