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Thread: Refinishing aluminum 075 tweeter

  1. #1
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    Refinishing aluminum 075 tweeter

    I'd like to diassamble 075 tweeter in order to refinish the aluminum bullet and cone. Can anyone advise a procedure that doesn't disrupt the integrity of the tweeter? Thx!

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  2. #2
    Senior Member BMWCCA's Avatar
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    The bullet nose should just unscrew (counter-clockwise) without much effort, but it has been on there perhaps half a century so you might need to grab it with one of those rubber can-opening helpers. I'd probably try some (brass) "steel" wool and see what you get. Obviously you won't' want to mess with those original red-wax seals. Often the Japanese restorers will polish the aluminum to a chrome-like shine or even plate them in gold. I'm assuming you just want them to look like they looked when new.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Phil,

    That's bad advice to give to "hifi".

    Unscrewing that central phase plug will twist//grind the base of the phase-plug against the inner//central clamping ring of the diaphragm and then distort the working portion of the diaphragm ( ultimately ruining it's performance ).

    Complete ( careful ) disassembly is required here all with the attendant loss of value ( due to losing the red wax-plugs ) just to gain a more pleasing look.



    Here's what happens with twisting;




  4. #4
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    Earl, thanks for the advice and glad I didn't jump in! What would you suggest for a refinishing procedure without diassambley?

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    My advice is to leave it as is.


  6. #6
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    Quote Originally Posted by Earl K View Post
    Phil,

    That's bad advice to give to "hifi".

    Unscrewing that central phase plug will twist//grind the base of the phase-plug against the inner//central clamping ring of the diaphragm and then distort the working portion of the diaphragm ( ultimately ruining it's performance ).

    Complete ( careful ) disassembly is required here all with the attendant loss of value ( due to losing the red wax-plugs ) just to gain a more pleasing look.

    Thanks for the correction. But it begs the question: What is the original order of assembly? Or is it meant never to come apart without diaphragm replacement?
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  7. #7
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    Quote Originally Posted by BMWCCA View Post
    Thanks for the correction. But it begs the question: What is the original order of assembly? Or is it meant never to come apart without diaphragm replacement?

    [A] Remove the rear decal hiding the through-bolt that holds the phase plug in-place ( here; the "phase-plug" = bullet-shaped nose-cone .

    [B] Remove the outer horn next ( this means, removing the 4x wax seals ).

    [C] While firmly holding the phase-plug to prevent it from turning ) remove the central screw/bolt.

    [D] Carefully lift phase-plug ( straight-off ) of the central clamping-ring of the diaphragm

    [E] Diaphragm is now ready to be un-soldered


  8. #8
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    Quote Originally Posted by Earl K View Post
    [A] Remove the rear decal hiding the through-bolt that holds the phase plug in-place ( here; the "phase-plug" = bullet-shaped nose-cone .

    [B] Remove the outer horn next ( this means, removing the 4x wax seals ).

    [C] While firmly holding the phase-plug to prevent it from turning ) remove the central screw/bolt.

    [D] Carefully lift phase-plug ( straight-off ) of the central clamping-ring of the diaphragm

    [E] Diaphragm is now ready to be un-soldered

    Thanks again. Once more JBL hides the goodies under a foil-cal!
    Mine are about 65-years-old. I think I'll leave them be.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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