5jr's why the epoxy on the mags?

Stevenmbell
Stevenmbell Posts: 60
edited May 2009 in Vintage Speakers
Can anyone tell me why I hear of people using jb weld or epoxy on the magnets?
2 CHANNEL:cool:
Belkin PF31Pure power/AV Conditioner
NAD C165BEE PreAmp Great Phono Section
B&K ST1400 S2 Power Amp
Audio Quest 4 Speaker Cables
ProJect RPM 1 Carbon
Ortofon Blue Cartridge
Quadio Interconnects
Denon 2910 DVD-A/SACD Player
Pangea SE 14 & AC9 Power Cords
Vifa DIY 3 ways Sound is incredible. :biggrin:
Post edited by Stevenmbell on
· Share on FacebookShare on Twitter

Comments

  • anton.chigurh
    anton.chigurh Posts: 239
    edited May 2009
    See post #4 below.

    http://www.polkaudio.com/forums/showthread.php?t=82029
    · Share on FacebookShare on Twitter
  • engtaz
    engtaz Posts: 7,664
    edited May 2009
    If I understand you correctly, it is to demagnitize the speaker so it does not mess with tube TV's.
    engtaz

    I love how music can brighten up a bad day.
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2009
    The magnets on the MW's used in the vintage Monitors and the SDA's have a tendency of shifting during shipping, if they're handled roughly, basically rendering the drivers useless. The JB Weld helps secure the magnet to the basket and greatly reduces the chances of that happening.
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • heiney9
    heiney9 Posts: 25,214
    edited May 2009
    engtaz wrote: »
    If I understand you correctly, it is to demagnitize the speaker so it does not mess with tube TV's.

    No, it's to keep the magnet from shifting during moving, shipping, etc. The 20+ year old glue that hold the magnet in place gives out eventually and when it does, it is impossible to realign the magnet and voice coil. I'm thinking about doing this to my drivers in both the 1C's and 5B's........mostly for peace of mind.

    One could add "bucking" magnets to shield a magnetic field from intefering with a CRT type tv.

    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!
    · Share on FacebookShare on Twitter
  • Stevenmbell
    Stevenmbell Posts: 60
    edited May 2009
    Not Good I just bought a pair of 5jr's on CL having them shipped.
    2 CHANNEL:cool:
    Belkin PF31Pure power/AV Conditioner
    NAD C165BEE PreAmp Great Phono Section
    B&K ST1400 S2 Power Amp
    Audio Quest 4 Speaker Cables
    ProJect RPM 1 Carbon
    Ortofon Blue Cartridge
    Quadio Interconnects
    Denon 2910 DVD-A/SACD Player
    Pangea SE 14 & AC9 Power Cords
    Vifa DIY 3 ways Sound is incredible. :biggrin:
    · Share on FacebookShare on Twitter
  • Stevenmbell
    Stevenmbell Posts: 60
    edited May 2009
    Where do I apply the jb weld anywhere between the mag and basket?
    2 CHANNEL:cool:
    Belkin PF31Pure power/AV Conditioner
    NAD C165BEE PreAmp Great Phono Section
    B&K ST1400 S2 Power Amp
    Audio Quest 4 Speaker Cables
    ProJect RPM 1 Carbon
    Ortofon Blue Cartridge
    Quadio Interconnects
    Denon 2910 DVD-A/SACD Player
    Pangea SE 14 & AC9 Power Cords
    Vifa DIY 3 ways Sound is incredible. :biggrin:
    · Share on FacebookShare on Twitter
  • shack
    shack Posts: 11,154
    edited May 2009
    heiney9 wrote:
    No, it's to keep the magnet from shifting during moving, shipping, etc. The 20+ year old glue that hold the magnet in place gives out eventually and when it does, it is impossible to realign the magnet and voice coil. I'm thinking about doing this to my drivers in both the 1C's and 5B's........mostly for peace of mind.

    H9 is correct. Once those magnets come loose it is nearly impossible to get them realigned. I had a bad experience with some speakers that were shipped to me by a genius who used ONLY packing peanuts in a single box to ship both speakers. Of course the speakers were shaken in every way imaginable during shipping by those "oh so carefull" package handlers at UPS. When it arrived the tweeter magnet was in the bottom of the speaker. I tried to epoxy it back exactly as it should have been, but it never was correct. I ended up purchasing a new tweeter for nearly the price I paid for the speakers.

    Making sure they don't come loose now is just good insurance against future problems.
    "Just because you’re offended doesn’t mean you’re right." - Ricky Gervais

    "For those who believe, no proof is necessary. For those who don't believe, no proof is possible." - Stuart Chase

    "Consistency requires you to be as ignorant today as you were a year ago." - Bernard Berenson
    · Share on FacebookShare on Twitter
  • Stevenmbell
    Stevenmbell Posts: 60
    edited May 2009
    I wish I had known! Thankyou for the explaination
    2 CHANNEL:cool:
    Belkin PF31Pure power/AV Conditioner
    NAD C165BEE PreAmp Great Phono Section
    B&K ST1400 S2 Power Amp
    Audio Quest 4 Speaker Cables
    ProJect RPM 1 Carbon
    Ortofon Blue Cartridge
    Quadio Interconnects
    Denon 2910 DVD-A/SACD Player
    Pangea SE 14 & AC9 Power Cords
    Vifa DIY 3 ways Sound is incredible. :biggrin:
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2009
    So it's impossible to realign the magnet if it gets shifted? I thought it was possible, just a real PITA. Correct me if I'm wrong though.

    I was reading a write up a while back on realigning shifted magnets. I'll have to see if I can dig it up. I forget if it was a write up referencing Polk drivers or something else.
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter
  • heiney9
    heiney9 Posts: 25,214
    edited May 2009
    There is a company out there that claims they can realign the magnet w/the voice coil. They either have a special jig they made or a special home made machine. I don't think it's possible to do it by hand.

    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!
    · Share on FacebookShare on Twitter
  • gdb
    gdb Posts: 6,012
    edited May 2009
    I posted this thread that I found over at AK a while ago. I'd come up with a similar concept after thinking about how the adjuster screws work to straighten a tree in a Christmas tree stand. If it doesn't work...Oh well, you're no worse off than you were before ! (busted 65XX driver):)

    http://www.polkaudio.com/forums/showthread.php?t=79649&highlight=magnet
    · Share on FacebookShare on Twitter
  • comfortablycurt
    comfortablycurt Posts: 6,745
    edited May 2009
    gdb wrote: »
    I posted this thread that I found over at AK a while ago. I'd come up with a similar concept after thinking about how the adjuster screws work to straighten a tree in a Christmas tree stand. If it doesn't work...Oh well, you're no worse off than you were before ! (busted 65XX driver):)

    http://www.polkaudio.com/forums/showthread.php?t=79649&highlight=magnet

    Ahh...there's the write up I was talking about. I couldn't remember where I'd stumbled across it.
    The nirvana inducer-
    APC H10 Power Conditioner
    Marantz UD5005 universal player
    Parasound Halo P5 preamp
    Parasound HCA-1200II power amp
    PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
    Audioquest Speaker Cables and IC's
    · Share on FacebookShare on Twitter