JBL 4435 restoration

Discussion in 'Speakers' started by Ingenia, Feb 11, 2019 at 6:02 AM.

  1. Ingenia

    Ingenia New Member

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    Hello to all the people.
    I'm new in this forum. I present my project of restoration of the big boxes JBL 4435
    First doubts:
    The membranes work correctly, but they are different.
    In case of replacement, which is better? Genuine JBL or Radian?
    The foam behind the membrane is damaged. What to put here?
    IMG_20190209_220810.jpg IMG_20190205_105133.jpg
     

     

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  2. GD70

    GD70 AK Subscriber Subscriber

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    @Alobar will have the info you need. I’m about to start a similar repair and planned to use some air filter foam I have from another project which he said should do the trick. Keep us posted, keep the pics coming and welcome to AK!
     
  3. grey

    grey AK Subscriber Subscriber

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    You can trim what you need out of the large format compression driver pads.
    JBL pad part# 60398

    Go with JBL parts on these classics.
    JBL diaphragm part# D8R2425

    +1:D Welcome!
     
    Alobar likes this.
  4. Ingenia

    Ingenia New Member

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    Thanks for the answers !!
    My driver is model 2421A. What membrane would be appropriate? D8R2425 ??
    IMG_20190208_082939.jpg
     
  5. grey

    grey AK Subscriber Subscriber

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    Alobar likes this.
  6. grey

    grey AK Subscriber Subscriber

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  7. Alobar

    Alobar Pulling out of the Last Chance Texaco.. Subscriber

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    After dinging one of my diaphragms I ordered a pair of Radians which had an almost identical sound to them.. I replaced one and compared a/b to the other and I would be hard pressed to hear any difference. I'd say either would be just fine and the Radians are a quality product made in USA. I'd avoid any of the ones made in China however.
     
  8. grey

    grey AK Subscriber Subscriber

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    Speaking of that, If you do decide on JBL parts, give them a good visual check. Check the DC resistance as well. They had a few QA issues when they moved production to Mexico. Hopefully it's fully sorted by now.
     
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  9. toddalin

    toddalin Super Member

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    You have 4435s with AlNiCo 2421s??? That has to be a rarity from right at the beginning of production.

    The correct diaphragm is the 2421 and not the 2425, though it will certainly work. The 2421 is aluminum and the 2425 is titanium. The aluminum is smoother (and highly valued), but will not take as much power, and not go quite as high as the titanium. But, there are many, myself included, who prefer the sound of the aluminum to the titanium.
     
  10. Ingenia

    Ingenia New Member

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    5
    The Low Frequency:
    IMG_20190208_082930.jpg
     
  11. mythless

    mythless Still have projects! Subscriber

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    Get the Radians over the titanium, they are much smoother, and nicer. I had a direct comparison between the Radians vs JBL titanium diaphragms in my LE85. Between OEM JBL and Radians, I could not tell the difference. So, it kind of depends if you're a purist or okay to mingle.
     

     

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  12. 1audiohack

    1audiohack Active Member

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    That’s the ideal speaker driver load in my opinion. The SFG woofers have lower distortion than their AlNiCo motor predecessors and the 2421’s sound better than what came after them.

    Both of those diaphragms look like JBL aluminum to me but closer pictures would be helpful. The rings are on again off again anodized so I doubt they are from the same run / age.

    You need someone to properly test them to see if they match in performance. They may be fine.

    I replaced the surrounds on my 4435’s with butyl rubber surrounds and would do that again in a heartbeat. I posted all about that on the Lansing Heritage forum.

    What condition is the rest of it all in?

    Barry.
     
  13. Ingenia

    Ingenia New Member

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    IMG-20190216-WA0000.jpg
    Replacement woofer rubber rings and ready to install
     
  14. Ingenia

    Ingenia New Member

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    IMG_20190217_115633.jpg IMG_20190217_115608.jpg IMG_20190217_115552.jpg IMG_20190217_115456.jpg IMG_20190217_115445.jpg IMG_20190217_115445.jpg IMG_20190217_115456.jpg IMG_20190217_115552.jpg IMG_20190217_115608.jpg IMG_20190217_115633.jpg

    Details of diaphragms
     

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