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Thread: Recharging Alnico/Ferrite magnets

  1. #1
    Junior Member magger's Avatar
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    Recharging Alnico/Ferrite magnets

    Hello forum,

    Question ... I know it is possible to recharge alnico magnets back to their respectable gauss values. Is it possible as well to recharge ferrite magnets? I own various JBL items (alnico drivers, ferrite based basses etc.) I have experienced that alnico JBL items have lost their gauss levels due improper storage/transport/load etc.

    That's the reason I post this question. Is there a difference between alnico vs. ferrite magnetic structure losing it's gauss due to mishandling, or (improper)load etc?

    MISC: I am from Europe, anyone aware of a place inside Europe that regausses magnets? The case here is varioius JBL items.

    Thank you,
    Magger

  2. #2
    Super Moderator Hofmannhp's Avatar
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    regaussing

    Quote Originally Posted by magger
    Hello forum,
    MISC: I am from Europe, anyone aware of a place inside Europe that regausses magnets? The case here is varioius JBL items.

    Thank you,
    Magger
    Hi Magger,

    the only company I know is "D. Lange u. Partner" in Berlin a well known Isophon specialist which regausses others too.

    HP
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  3. #3
    Steve Gonzales
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    a good read

    You may find this interesting:
    http://audioheritage.org/vbulletin/s...ead.php?t=4031

    There is a search function here that is helpful. It is located in that thin black bar located above. I've never heard of recharging a ferrite magnet as part of routine maintenance. It is strongly recommended to recharge AlNiCo drivers here though.

  4. #4
    Junior Member magger's Avatar
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    Steve and Hoffmann,

    I was wondering if you have any idea about how much it costs to regauss alnico magnets, and if it's possible to regauss the magnets without removing the diaphragm?

    Thank you for your inputs.
    Thank you,
    Magger

    JBL ... quality of life.

  5. #5
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    OCS quotes $45 just to regauss or $25 if you are having the speaker redone. Thus, it seems logical to assume that they can do a working speaker. I think JBL quotes (quoted) $27.

    Quote Originally Posted by magger
    Steve and Hoffmann,

    I was wondering if you have any idea about how much it costs to regauss alnico magnets, and if it's possible to regauss the magnets without removing the diaphragm?

    Thank you for your inputs.

  6. #6
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by magger
    ... and if it's possible to regauss the magnets without removing the diaphragm?
    Yes.


    Widget

  7. #7
    Super Moderator Hofmannhp's Avatar
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    Carl Friedrich Gauss

    Quote Originally Posted by toddalin
    ..... to regauss .......
    Hi All,

    a man to remember, ...certainly as important like James B. Lansing.
    Carl Friedrich Gauss 1777 - 1855,... born in Braunschweig / Germany.
    HP

    BTW: he looks a little ugly hearing some want to recharge Ferrites
    Attached Images Attached Images  
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  8. #8
    Senior Member Guido's Avatar
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    Quote Originally Posted by Mr. Widget
    Yes. Widget
    Also the Alnicos? I don't think so.

  9. #9
    Administrator Mr. Widget's Avatar
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    Fear not Guido... It may depend on the equipment that a specific shop has, but OCS does them as complete speakers.


    Widget

  10. #10
    Senior Member edgewound's Avatar
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    OCS does recharge assembled, coned-up speakers...and without cones or diaphragms installed.

    The problem with recharging assembled speakers is there is no way to check the flux density in the gap...just hope it's fully charged. It's really the only thing to do if you don't want to recone a vintage speaker...like an Altec 417 for guitar...or a D120/130/140F that still has OEM parts
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

  11. #11
    Senior Member tom1356's Avatar
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    Is there someone in the Boston area who recharges alnico magnets with the cone in?

  12. #12
    RIP 2011 Zilch's Avatar
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    To the best of my knowledge, I've never run into a driver that required recharging.

    From the discussions here, there's only three places in the U.S. that do it, and one known in Europe, so it isn't "routine."

    Yeah, I read the article about alnicos losing strength over time. Might be worthwhile if somebody relinked to it in this thread.

    I don't believe it's even a consideration with ferrites, tho, including if the magnet is disassembled from its "keeper."

    What's JBL's direction to its authorized reconers on this subject?

    Then again, the question is, "How would I know?"

    Gaussmeter if it's a compression driver with diaphragm removed or a coneless basket?

    Like, which, and how much to acquire one? Are we talking hobbiest gear here?

    With intact woofers, we can measure the BL product with WT2, perhaps?

  13. #13
    Steve Gonzales
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    routine

    I've read that an alnico driver should be recharged here so many times that I figured it was routine to do so. I've never run into one that needed it either. Can't IMAGINE what hell I would have caught if I were to advise otherwise Zilch

    Here are some suggestions by people whose opinion you might respect
    http://audioheritage.org/vbulletin/s...harging+alnico

  14. #14
    Administrator Robh3606's Avatar
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    To the best of my knowledge, I've never run into a driver that required recharging.

    I've never run into one that needed it either.

    Well I have not either so we 3 with this experience. That does not mean however that they should not be. I think it all depends on how hard the drivers are used. All my Alnico drivers are from home systems and that could make all the difference. I don't think you see this in home system drivers as often as Pro Drivers. I also think any reduction in flux would be much less for the same reason. How would you know if a driver had lost 10% of it gap strength?? What do you have to compare it to?? Not like we all have a NOS bin to pull from for comparisons. Home system drivers just don't take the kind of abuse a Pro Driver does on one tour. Some of these drivers have been in systems for decades under god knows what conditions. With Pro drivers I think it would be a foolish gamble to recone without checking the gap strength.

    Rob

  15. #15
    Steve Gonzales
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    exactly

    That doesn't mean I recommend the contrary. So, given that, unless you know where and how a driver has been used, every minute of it's work cycle, I suggest you recharge it if you can.

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