• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Dented dome on JBL L96 tweeter

gonzothegreat

gonzothegreat

Super Member
Found a pair of JBL L96 at GW with foam issues and a dented dome tweeter. The tweeter dent has me puzzled as the dome is protected by a fairly heavy metal grill and there don't appear to be any dents in it.

What's the easiest way to pop the dome back into shape? I scoured AK and painters tape and vacuum cleaners seem to be the top methods. I suspect the vacuum cleaner trick might rip the dome and the tape might not get all the creases. One AKer suggested a syringe with a suction cup but I need details on the correct cup.

Finally, how do I remove the protective grill from the L96 tweeter? I'm a little gunshy about ripping open a tweeter and possibly tearing the leads off. I've killed a few tweeters this way and I don't want another casualty...
 
Register to hide this ad
might try a drop of glue and a piece of string, let it dry ,pull it out gently, and cut off the string.
 
Unscreq the three allen hex screws carefully. Carefully remove the diaphragm (glued on) being careful of the voice coil. You will be able to push it out from the back...you may crease it though.
 
Unless the dent compresses the damping material behind it, I don't believe the actual shape has that much to do with how it sounds. If you can't hear a problem, let it be. I know that looks are sometimes as important as function, but if the repair doesn't work, you're stuck with a tweeter that looks AND sounds bad.

-Ed
 
Take a toilet tube and place it over the tweeter and suck gently back on the tweeter until you hear it go pop! It should be back in the original position don’t heavens above use a vacuum cleaner the pressure is too much and you might make the damage worse that it already is.

troll.jpg
 
The screen is held in by the rubber O-ring around its perimeter. Once you carefully remove that, the screen will come off.

The dome is hard phenolic with a vapor-deposited (or painted, depending upon vintage) aluminum coating.

It MAY pop back out with CONTROLLED application of vacuum. If not, you'll have to remove the diaphragm and push it out from behind, as described above.

Re-installing the diaphragm will require the use of a signal generator to achieve optimum voice coil alignment.

Repaint the aluminum, if necessary, with modeler's aluminum paint.

The dome is a hemispherical radiator of the VHF. Yes, it matters.

Factory replacement diaphragms are NLA.

The O-rings are available.

L96s are highly prized JBLs.

[Let a pro do it; the resurrounds, too....]
 
Just to wrap up this thread and let everyone know how it turned out - Mission Accomplished. :)

Once the late Zilch chimed in, I went to the local home improvement store for a suction cup and syringe. I poked a hole in the center of the suction cup so I could mount it on the syringe. The mesh was carefully removed to expose the phenolic dome. I licked the cup to provide an airtight seal and applied it to the dented dome. A slow pull on the syringe popped it back out. It wasn't absolutely perfect but damn close. The mesh was reinstalled and the o-ring was carefully poked back into the groove (although it had to be trimmed down due to stretching).

The L96 sat in storage for the better part of two years before I decided to dig them up last summer so I could put them on Craigslist. I put them in my bedroom system to test them out again and I couldn't stop listening to them. They're still hooked up as I type this.

Damn - I miss Zilch's posts...
 
My 96s were in storage as well. About a month ago I brought them out of the basement. Wow! Now I remember why I fell in love with them six years ago.

cubdog
 
I bought a pair of Celestion 1's on Ebay...the guy packed them with one facing up with the grill off...needless to say one tweeter was crushed in shipping... I took the tweet apart ...using a round handle from a screwdriver and pushed out 98% of the crushed dome..think it is titanium...cause I figured it was ruined...it made crackling noises everytime the screwdriver rounded it out!!...but it works perfect!.... looks 98% perfect! small creases...not very noticable now with the plastic ribs crazy glued back in place.
 
You must log in or register to reply here.
Back
Top Bottom