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Thread: 4365 has quality problems

  1. #46
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    Quote Originally Posted by smooth dancer View Post
    The sound is as always very very good.


    Wow, that diaphragm definitely has a Shroud of Turin thing going on.


  2. #47
    Senior Member edgewound's Avatar
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    Quote Originally Posted by smooth dancer View Post
    Some pics of mine 476mg. The speakers were bought brand new Des 2011. My listening room have a steady temp around 20-22˚celsius.
    Yes....but the humidity in Oslo today is 86%, and 74% average year round. 8 years of accumulated moisture is going to have an effect, as you can see. Once the moisture goes in, it's not coming out without leaving some residue behind.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

  3. #48
    Senior Member Mctwins's Avatar
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    Quote Originally Posted by smooth dancer View Post
    Some pics of mine 476mg. The speakers were bought brand new Des 2011. My listening room have a steady temp around 20-22˚celsius.
    It looks nice and the cables seems to be as Martin wu's picture regarding the faston. My wrong here, Sorry Martin!!

    But your cable attaching to the diafragman looks different. Flat wire contra round.

  4. #49
    Senior Member Mctwins's Avatar
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    I can agree that moisture can be a problem.

  5. #50
    Senior Member baldrick's Avatar
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    Had to open mine and it was easy without removing the driver.And for me it looks good!? But the voicecoil.... is this OK or could it be damaged?
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  6. #51
    Senior Member baldrick's Avatar
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    Is this damaged?
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  7. #52
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    Baldrick, your voice-coil looks good-enough ( iow; its not damaged ).
    - It's just not the cleanest coil winding job that I've seen.

    On a different matter;

    In my opinion, you should remove the driver body from the horn before replacing the diaphragm.

    Working on the driver ( with the gap vertically oriented ) is all too easy to make a mistake during re-assembly.

    IME, it's safer/better to work on drivers when you can walk around them ( 360deg ).


  8. #53
    Senior Member Mctwins's Avatar
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    Quote Originally Posted by baldrick View Post
    Had to open mine and it was easy without removing the driver.And for me it looks good!? But the voicecoil.... is this OK or could it be damaged?
    Looks good to me!

  9. #54
    Senior Member Mctwins's Avatar
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    I am not gonna open mine, don't have any moisture in my room. As long it's sounds fine I am not gonna bother with this issue. Maybe in 10 years

  10. #55
    Senior Member pos's Avatar
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    ignorance is bliss

  11. #56
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    Can TrueExtent Be diaphragms be installed in the 476Mg core?

  12. #57
    Administrator Robh3606's Avatar
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    ignorance is bliss
    Yes count me in as well not going to open mine either unless a measurement goes funky or an impedance sweep goes awry

    Rob
    "I could be arguing in my spare time"

  13. #58
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    Quote Originally Posted by bubbleboy76 View Post
    Can TrueExtent Be diaphragms be installed in the 476Mg core?
    That's a good question to which I personally don't have an answer.


  14. #59
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    Quote Originally Posted by sebackman View Post
    That looks really odd.

    Normally the phase plug never rust from what I have seen. It is the steel outer ring that corrodes and that is not uncommon due to leaking back cover or water coming in from the horn side.

    I have never seen an original 4" driver with rust on the phase plug. Corrosion from water yes, but not rust. If it indeed is rust? -And is the phase plug corroded from water the outer steel ring almost always shows some rust. This does not.

    Easy to clean up the steel ring but not in the phase plug.

    Can it be something from the inside of the dia due to excessive heat? Glue perhaps? Can you post a picture of the phase plug side of the dia.

    Is it original JBL dia’s? I have not seen those lead covers on the leads from the WC on any other dia. I don’t have them on my 475Nd dias.

    I have not seen Aquaplas coated dias loosing coating like in the picture so that may also indicate heat maybe? On the other hand, I do not have any Mg’s just Ti, Alu and Be.

    “Bubbleboy76” and “hlaari” (and probably many more) here on LH are using 476MG and has opened them so they should be able to bring some light on the coating issue.

    Kind regards
    //RoB

    I need to check out my 476Mg drivers, it does not look good like this




    Ari

  15. #60
    Senior Member ivica's Avatar
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    Quote Originally Posted by Earl K View Post
    That's a good question to which I personally don't have an answer.

    Hi Earl K,

    what kind of problem can expected to use Be-Trx diaphragm with 476 core.
    I can imagine that Mg diaphragm would produce higher F/R response then Be-Trx one.
    Using JBL Be diaphragm, would be different story, I think.....

    regards
    ivica

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