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JBL 8340 Surround Glue.

post #1 of 21
Thread Starter 
Well I just found a pair of 8340's locally. It's apparently pretty common that the surrounds on the 10" woofers deteriorate over time.
I got a good deal and want rears that can keep up with the 4Pi's (build thread coming soon!)

The pair I got are original everything, but the foam on the drivers was replaced a couple months ago.
Problem is, the edge where the foam surround meets the cone, has a very slight gap where it comes away.
This means that the drivers are not 100% airtight.

My question is, will this have a huge effect on sound quality?
What kind of glue can I use to seal these up?

It looks like the JBL tech used this black/clear-looking kind that stays sticky and malleable even after its dried.

I gave them a listen and they still sound fantastic.
For clarification the model is 127H-2.

Thanks
Edited by Thatsnasty - 10/7/12 at 4:35pm
post #2 of 21
Got a picture?

You probably want something like this.
post #3 of 21
Thread Starter 
Quote:
Originally Posted by Stereodude View Post

Got a picture?
You probably want something like this.

Yeah that looks about right.
Sorry about the bad picture.


You can just see how right near my finger it pulls away from the cone, as if he didnt use enough glue.
Edited by Thatsnasty - 10/7/12 at 4:58pm
post #4 of 21
I like those 8340's. I use a pair in my system and you are right, the foam does deteriorate. I had to replace the foam surround on one of mine a couple years ago.
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post #5 of 21
Thread Starter 
Quote:
Originally Posted by AV Science Sales 5 View Post

I like those 8340's. I use a pair in my system and you are right, the foam does deteriorate. I had to replace the foam surround on one of mine a couple years ago.

I only demoed them at the guys house I got them from... very nice sounding, and decent bass.
I'm itching to get these set up, that glue Stereodude posted looks decent.
post #6 of 21
Quote:
Originally Posted by Thatsnasty View Post

I'm itching to get these set up, that glue Stereodude posted looks decent.
I replaced the foam surround on an old JL Audio 8W6 last weekend with a kit from them. The black glue worked well. It sets up pretty fast though.
post #7 of 21
Thread Starter 
Quote:
Originally Posted by Stereodude View Post

I replaced the foam surround on an old JL Audio 8W6 last weekend with a kit from them. The black glue worked well. It sets up pretty fast though.

Good because I already ordered it! haha.
Honestly I have no idea how much having a minor air hole in the surround will effect the quality but I'm OCD when it comes to do things right, and I want it to be perfect.
If anyone else has any feedback feel free to chime in.

Coming soon > 4 PI build thread and some other goodies.... just looking about getting a cheap camera that takes better pictures then my phone.
post #8 of 21
Thread Starter 
Just repaired the 8340's and plugged the cabinet holes someone made in the back, they should be good for tomorrow!
The bad news... all of my rechargable batteries are dead (as in dead for good) so it's going to be a few days before the I get pictures and start with the 4pi thread.
post #9 of 21
A good way to make sure the gap is maintained while gluing on a new surround is to play a 40hz test tone while gluing the surround in place. This helps to keep the coil centered. A lot quicker and easier than cutting off the dust cap and shimming the coil and replacing the dust cap.
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post #10 of 21
Quote:
Originally Posted by AV Science Sales 5 View Post

A good way to make sure the gap is maintained while gluing on a new surround is to play a 40hz test tone while gluing the surround in place. This helps to keep the coil centered. A lot quicker and easier than cutting off the dust cap and shimming the coil and replacing the dust cap.
Except in cases where the spider is damaged the spider alone will usually keep the coil centered when replacing the surround. Shimming the coil is only mandatory with a full recone.
post #11 of 21
Thread Starter 
Thanks for the advice guys.
It was just "patching" a hole from the surround edge to the cone edge so that it's airtight, both weren't glued very well but it's good now.

Now that you mention coil centering... one of the 127H woofers makes a very faint "rub" noise when you push the cone in, and the other is completely silent
Me thinks the tech is to blame for this too. Hope it's not audible as I really don't want to tear the driver apart to shim it.
post #12 of 21
Guys, where did you buy the kit to replace the surrounds on the 8340 and do you know what driver it uses? Thanks!
post #13 of 21
Thread Starter 
Quote:
Originally Posted by 316 View Post

Guys, where did you buy the kit to replace the surrounds on the 8340 and do you know what driver it uses? Thanks!

The bass driver in the 8340's (Wood cabinet, NOT 8340a's) is the JBL 127h-2 .
I never re-coned them myself, just patched them because apparently the tech didn't seal them good.
You can buy the re-cone kits on Ebay, but I'd be careful as some of them tend to be junky.

The good thing is generally the recone is because of the surround rotting, so you could probably get away with a cheaper one? I'm not sure, either way, hope this helps.
post #14 of 21
Thanks...yeah I have the wood caninets and had found the driver number last night. Thank you for responding!!
post #15 of 21
I reconed some JBLs about a year ago. I got the foam cones off of ebay and it came with glue that was recommeded by the seller. Turns out the glue was your every day "white cow" glue. I applied it to the inside ring, spread it thin with a brush and let it dry a bit so it would get tacky, applied it to the foam in the same manner and then placed it and let it dry with a bunch of quarters as weight on the foam for about a day or two.

It has been a year and I have seen zero separation thus far.
post #16 of 21
One of the Eric's here refoamed 20-40 pairs so he could probably give some insight. I have 2 pairs from him and he did a great job.
post #17 of 21
Thanks" do you have a link to him? Pm me if so....thanks
post #18 of 21
I forget if it was EricH or the Eric in Alabama
post #19 of 21
Hey guys, I sold the 8340's to Jesse and quite a few other guys here in Canada. The foam surrounds can be bought from mainelectronics.com (Part# FSA0950-0712) for 6-7 bucks each. They also sell glue but you can use Aileene's Tacky or Fabric Fusion Glue.

Hope this helps,

Eric
post #20 of 21
Thank you! Did you shim voice coil? I'm picking up 8 and they all need new surrounds but I've never done the surround replacement....I like the 40hz trick mentioned that way I would not need to remove dust cap...
post #21 of 21
No need to shim... like Bill said earlier, the spider should keep things centered. I would also suggest you run a 40hz test tone while gluing the surround - you will hear it right away if the VC is rubbing.
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