Refinishing aluminum 075 tweeter

[hifi]

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!

91177

91178

91179

[BMWCCA]

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.

[Earl K]

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;

https://www.audioheritage.org/vbulletin/attachment.php?attachmentid=64948&stc=1&d=1427281776

https://www.audioheritage.org/vbulletin/attachment.php?attachmentid=64943&d=1427234854

[hifi]

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

[Earl K]

My advice is to leave it as is.

:)

[BMWCCA]

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?

[Earl K]

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

:)

[BMWCCA]

[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.