Page 1 of 7 123 ... LastLast
Results 1 to 15 of 104

Thread: 4365 has quality problems

  1. #1
    Senior Member martin_wu99's Avatar
    Join Date
    Jul 2007
    Location
    Xi'An,China
    Posts
    1,489

    4365 has quality problems

    Today two local audiophile complained that their 4365s have quality problems after two years using,they said thses problems are very common in 4365.
    1.476Mg cladding material is easy to exfoliate,this will block the gap.
    2.the magnetic steel is easy to rust.
    These problems caused the compression drivers don't have same SPL.
    Why?
    Attached Images Attached Images      
    46 lover

  2. #2
    Senior Member martin_wu99's Avatar
    Join Date
    Jul 2007
    Location
    Xi'An,China
    Posts
    1,489

    more pixes

    more pixes
    Attached Images Attached Images    
    46 lover

  3. #3
    Administrator Robh3606's Avatar
    Join Date
    Apr 2003
    Location
    Rocinante
    Posts
    7,998
    That's weird how did the aguaplas end up in the gap?? The diaphragm is a physical barrier and gravity, with the driver mounted in the cabinet, is going to make it fall into the back shell cavity. Sure it not just the corrosion around the edge of the gap? That corrosion is concerning.

    Rob
    "I could be arguing in my spare time"

  4. #4
    Senior Member
    Join Date
    Oct 2003
    Location
    Texas
    Posts
    1,732
    I've never seen one cracked open, seems strange that they would Aquaplas a Mg 'phragm.

  5. #5
    Member sebackman's Avatar
    Join Date
    Feb 2004
    Location
    Europe
    Posts
    499
    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
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  6. #6
    Member sebackman's Avatar
    Join Date
    Feb 2004
    Location
    Europe
    Posts
    499
    Not sure those are original dias.... Looks like someone swapped in something else.

    I have never seen a JBL dia looking like that with leads trough the dome.

    Kind regards
    //Rob
    The solution to the problem changes the problem.
    -And always remember that all of your equipment was made by the lowest bidder

  7. #7
    Senior Member
    Join Date
    Apr 2003
    Location
    Richmond Hill, Ont.
    Posts
    4,688
    Robh3606 has some 476Mg drivers.

    I suppose there's good reason now for everyone with these drivers to check underneath the diaphragm and look for rust.

    OTOH, what we are looking at could well be the realized consequences of local counterfeit parts ( or whole systems ).

    I'll reserve my indignation till I see world-wide evidence of any wrong-doings on JBL's part .



    PS; the dressing of diaphragms lead-in wires is interesting being situated on the dome side of the diaphragm ( a la Altec )
    >> typically JBL has tucked those lead-ins under the diamond surround ( going directly to the voice-coil ).
    - Mind-you, this is my first look at a 476Mg diaphragm that I can remember.

    - What Rob just said.

  8. #8
    Senior Member martin_wu99's Avatar
    Join Date
    Jul 2007
    Location
    Xi'An,China
    Posts
    1,489
    Quote Originally Posted by Robh3606 View Post
    That's weird how did the aguaplas end up in the gap?? The diaphragm is a physical barrier and gravity, with the driver mounted in the cabinet, is going to make it fall into the back shell cavity. Sure it not just the corrosion around the edge of the gap? That corrosion is concerning.

    Rob
    Only the edge is rusty,this stucked diaphragm and make SPL reduced.almost every 4365 has this problem.
    If you have 4365,please check it
    46 lover

  9. #9
    Senior Member martin_wu99's Avatar
    Join Date
    Jul 2007
    Location
    Xi'An,China
    Posts
    1,489
    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
    It is a authentic product purchased from local JBL dealer,not smuggled goods.
    46 lover

  10. #10
    Senior Member
    Join Date
    Apr 2003
    Location
    Richmond Hill, Ont.
    Posts
    4,688
    Quote Originally Posted by sebackman View Post
    Not sure those are original dias.... Looks like someone swapped in something else.

    I have never seen a JBL dia looking like that with leads trough the dome.

    Kind regards
    //Rob
    Quote Originally Posted by me
    PS; the dressing of diaphragms lead-in wires is interesting being situated on the dome side of the diaphragm ( a la Altec )
    >> typically JBL has tucked those lead-ins under the diamond surround ( going directly to the voice-coil ).
    - Mind-you, this is my first look at a 476Mg diaphragm that I can remember.







  11. #11
    Senior Member
    Join Date
    Nov 2008
    Location
    Gothenburg, Sweden
    Posts
    760
    Both my 476Mg were heavily corroded on the diaphragm. They were cleaned, and measured like new. But still looks like shit.
    I have picture somewhere.
    So this is a general problem. I will contact my service guys.

  12. #12
    Senior Member martin_wu99's Avatar
    Join Date
    Jul 2007
    Location
    Xi'An,China
    Posts
    1,489
    Quote Originally Posted by bubbleboy76 View Post
    Both my 476Mg were heavily corroded. They were cleaned, and measured like new. But still looks like shit.
    I have picture somewhere.
    So this is a general problem. I will contact my service guys.
    Thank you for telling the truth.
    Not occasional one person told me,as i know at least 4 pairs of 4365 have these problem.they said every 4365 have these problems.
    46 lover

  13. #13
    Senior Member
    Join Date
    Apr 2003
    Location
    Richmond Hill, Ont.
    Posts
    4,688
    Quote Originally Posted by bubbleboy76 View Post
    Both my 476Mg were heavily corroded on the diaphragm. They were cleaned, and measured like new. But still looks like shit.
    I have picture somewhere.
    So this is a general problem. I will contact my service guys.
    Quote Originally Posted by Martin
    Thank you for telling the truth.
    Not occasional one person told me,as i know at least 4 pairs of 4365 have these problem.they said every 4365 have these problems.
    JBL should make good on the necessary repairs to stabilize the rust problem.

    JBL should also make sure the refurbed drivers are performing back up to spec.

    All at Harman's cost.

    OTOH, if someone wants to make an attempt at stabilizing the rust situation ( on the outer edge of the phase plug ) I recommend treating the problem area with a rust converter product that contains Phosphoric Acid & Tannic Acid ( as the active ingredients ).



    These rust converter products are pretty common in countries having a real winter and where the use of road salt leads to all sorts of rust problems.

    Here's a product available here in Canada for the DIY crowd ( every northern type country should have something comparable ).




    Attached Images Attached Images

  14. #14
    Senior Member
    Join Date
    Nov 2008
    Location
    Gothenburg, Sweden
    Posts
    760
    Pic of one of my 476Mg diaphragm (to the right) after cleaning.
    Attached Images Attached Images  

  15. #15
    Senior Member martin_wu99's Avatar
    Join Date
    Jul 2007
    Location
    Xi'An,China
    Posts
    1,489

    another pair of 4365

    pixes
    Attached Images Attached Images     
    46 lover

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. My new jbl 4365
    By Mctwins in forum Lansing Product General Information
    Replies: 132
    Last Post: 02-08-2016, 07:09 AM
  2. Jbl 4365
    By saeman in forum Lansing Product General Information
    Replies: 240
    Last Post: 05-15-2014, 11:13 AM
  3. 4365
    By Techbot in forum System Information
    Replies: 0
    Last Post: 08-25-2010, 02:58 PM
  4. JBLs: quality then vs. quality today?
    By Lee6 in forum Lansing Product General Information
    Replies: 22
    Last Post: 06-21-2006, 12:13 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •