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JBL 12" Refoaming - How hard is it really?

brhalltx

brhalltx

Active Member
I'm pondering, especially after a $400 quote to refoam two 128Hs and two PR300s.
Heat and humidity and garage aside (it's hell living in the heat and humidity capitol of Texas; can't glue inside, due to she-who-thinks-she-must-be-obeyed and asthma and allergies), it doesn't look too hard, other than making sure everything is aligned.

Is it better to use the test tone or shims? Or both?

And, does the 128H have foam under the dust cover that should be removed/replaced?
 
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I bought the kits for 4 10 inchers on ebay, followed the instructions, and had them done in a little over an hour. They came with a test tone CD, but my player was down, so I just laid them on a flat surface and did it by 'feel'. Didn't even remove the dust caps.

Came out perfect. Use Aileen's glue if you run out of what comes in the kit.
 
Hi brhalltx.

I've never touched the JBL woofers you speak of however I get the feeling you haven't refoamed a woofer before, correct?

If this is the case then take it from me it's far easier than you think :) Very daunting at first and if in fact you haven't refoamed a speaker before and are paranoid of stuffing something up I suggest you try doing it on a sacrificial woofer first just so you can prove to yourself how easy it is. You'll finish the job wondering why you hadn't done it sooner... seriously. It's so easy you might even start thinking of opening up your own speaker repair business :P

Take your time and it's a breeze... oh and the larger the cone the easier it is. I've done quite a few over the last couple of years and find the larger drivers a lot easier to do. The smaller cones I've done (4") are a lot fiddlier and far more difficult to align. Trust me, after refoaming all 18 fullrange drivers in a pair of Bose 901s I know :yes:
 
I did a pair of JBL L150's that have a 12" woofer and 12" passive radiator in each cabinet. Not hard at all except the surround mounts under the cone and is a little harder than the ones that mount on top. I got my surrounds from Rick Cobb. As you can see, they fit so perfectly that you could not misalign them if you tried.
 
SteveAndBell said:
Hi brhalltx.

I've never touched the JBL woofers you speak of however I get the feeling you haven't refoamed a woofer before, correct?
Click to expand...

I haven't, but it certainly wouldn't be the most difficult thing I've done (I've worked on cars and electronics most of my life, not to mention computers). ;) Much better than fixing the *@#E# swimming pool equipment...

I'm glad to hear the bigger drivers are easier. I'd start with the passive radiators, but I do have other speakers I should check. Now what did I do with those ARs and B&Ws? Or my 8216A that I use for a center channel speaker...
 
HTHMAN said:
I did a pair of JBL L150's that have a 12" woofer and 12" passive radiator in each cabinet. Not hard at all except the surround mounts under the cone and is a little harder than the ones that mount on top. I got my surrounds from Rick Cobb. As you can see, they fit so perfectly that you could not misalign them if you tried.
Click to expand...

I've seen that picture before. ;) And your mention of how well the surrounds fit; I'm leaning towards leaving the dust caps alone.

Did you have to use MEK to remove the remnants of the old surrounds?
 
bentpencil said:
I bought the kits for 4 10 inchers on ebay, followed the instructions, and had them done in a little over an hour. They came with a test tone CD, but my player was down, so I just laid them on a flat surface and did it by 'feel'. Didn't even remove the dust caps.

Came out perfect. Use Aileen's glue if you run out of what comes in the kit.
Click to expand...

Impressive. And I'll probably pick up some Aileen's to have on hand.

And then there's recovering the grills...
 
Comment - Passive radiators have no voice coil, so alignment not a problem.

My preference is to use shims, especially with JBL (close tolerance gaps) If you have a well ventilated area, the glues used by JBL are solvent based, and the caps can be removed after softening the glue with MEK. MEK (like acetone) is highly flammable and should used with great care (or not used) YMMV
 
sregor said:
Comment - Passive radiators have no voice coil, so alignment not a problem.

My preference is to use shims, especially with JBL (close tolerance gaps) If you have a well ventilated area, the glues used by JBL are solvent based, and the caps can be removed after softening the glue with MEK. MEK (like acetone) is highly flammable and should used with great care (or not used) YMMV
Click to expand...

That's exactly why I'd do the passive radiators first; get a little practice...

I'm aware of MEK (I've never set any on fire in 35+ years of using it...), but certainly a good reminder, especially the well ventilated part. Any work with solvents will certainly be outdoors.
 
Prepping the cone and basket is super important. The outcome's only as good as the prepping.
Take your time. Some of the YouTube videos are sloppy. Still worth a look.
You may see what you shouldn't do.
 
jblmar said:
Prepping the cone and basket is super important. The outcome's only as good as the prepping.
Take your time. Some of the YouTube videos are sloppy. Still worth a look.
You may see what you shouldn't do.
Click to expand...

I'll take a look; I did see a YouTube from one of the big speaker repair places...

As for prep, has anybody used MEK substitute for cleaning the cone and basket? I doubt I have any real MEK, and it seems to be hard to get...
 
brhalltx said:
And, does the 128H have foam under the dust cover that should be removed/replaced?
Click to expand...

I believe the JBL L112 used the 128H woofer, right? I refoamed a set of L112s a couple years ago, and indeed the foam pole vent covers inside had dried up and were working themselves loose. I replaced the foam with small circles of grill fabric which I figured was acoustically transparent like the foam, would keep dust, dirt and spiders out of the voice coil, and would not degrade over time like the foam.

If I remember right, I used some mineral spirits for cleaning left over adhesive from the baskets. The remnants of the surrounds came off the woofer cones with just some gentle rubbing with my fingertips.

Here's a link to a photo of the deteriorating foam that I posted in an old thread:

http://www.audiokarma.org/forums/attachment.php?attachmentid=264272&d=1300897491
 
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brhalltx said:
I've seen that picture before. ;) And your mention of how well the surrounds fit; I'm leaning towards leaving the dust caps alone.

Did you have to use MEK to remove the remnants of the old surrounds?
Click to expand...

Don't remember exactly what I used on the JBL's but usually I start by rubbing the adhesive off with my finger and thumb. Next I try denatured alcohol and if that fails, I move to acetone cautiously-that stuffs melts about anything. I use Aileen's tacky glue for everything and have never had it fail. I am in the "do not cut the dust cap off" camp. With a little practice, you can feel if it is right. A test tone is a good alternative. I believe if you shim, you can stretch the surround to one side and you will not know it until you pull the shims and the cone shifts. People have success with all three methods. Do what makes you feel comfortable.

If you contact Rick Cobb directly instead of his eBay store, he will sell surrounds without the kit.
 
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I refoamed a pair of those woofers last week using a kit from Rick Cobb which included a test tone CD. This was my second pair of 128H woofers and maybe my 25th pair of speakers refoamed. I've always used the test tone with no problems. I also use clothespins to keep the surround from shifting once it's in the right spot.

If you are nervous, get a $5 pair of crap speakers from Goodwill and practice on them. I've always used a tool that can be found on eBay under the title "Scotty Peeler Set of 2 Metal SP-2 Price Sticker Label Removers NEW". This is a great tool that I love so much, when the first one I had broke after years of use, I looked around until I found some identical ones on eBay.
 
I've done the woofs on both the L80t3 (10") and the L100t3 (12") JBLs and used the test tone method. Worked fine for me. For cleaning the metal part I used a hardwood dowel shaped into a chisel and also cleaned the cone with a little rubbing of the fingers. You really don't have to get every trace of glue off but you'll need to get rid of as much of the old foam as you can. I wouldn't use MEK, laquer thinner or acetone. You don't need them for this job. A little bit of mineral spirits is OK.

Another satisfied customer of Rick Cobb's surround kits here. They're right and contain all you'll need to do the job.
 
Thanks for the answers and suggestions, everyone. I'm gathering the bits and pieces, and may have time to start on this next week.
 
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