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JBL 8340 Surround Glue.

post #1 of 11
10/7/12 at 3:43pm
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
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post #2 of 11
10/7/12 at 4:42pm
Got a picture?

You probably want something like this.
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post #3 of 11
10/7/12 at 4:52pm
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
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post #4 of 11
10/7/12 at 5:28pm
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 11
10/7/12 at 9:37pm
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.
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post #6 of 11
10/8/12 at 4:52am
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.
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post #7 of 11
10/8/12 at 10:12pm
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.
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post #8 of 11
10/21/12 at 10:14pm
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.
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post #9 of 11
10/22/12 at 5:36am
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 11
10/22/12 at 6:20am
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.
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post #11 of 11
10/22/12 at 11:00pm
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.
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