Just completed a K120 recone based on this thread. Great info!
Just completed a K120 recone based on this thread. Great info!
Did my first re-surround on a set of L46s. These little buggars sound great. Thanks for the info, It costs more to recone them than to replace them. What a waste! Now they're good for 15 more years. i don't think I would have done it if not for this thread,
I know this is an old thread but I thought I'd give it a bump for those new to LH looking for excellent instructions on refoaming/reconing woofers. Also, an "attaboy" for Bo for the good pics and instructions. I am watching the glue dry on a pair of L111a's , out of 4313's. At least I have that 30 hz tone to keep me company .
I found a little trick doing these. An 8" wire tie is just the right width to press down the foam into the frame when gluing. Grasping the wire tie about an inch from the end and lightly pressing the foam down, while turning my lazy susan , made for a very efficient placement. No glue on the fingers, as well.
First and foremost, huge thanks to Scott Koeller (SMKSoundPro) for helping me through my first attempt at this.
Scott – thanks for your immediate replies to my PMs, your clear answers to my questions and your expert advice.
Secondly, big thanks to Rick Cobb, who supplied a ‘Beta’ surround, free of charge - then the complete kit (Foam Surround JBL 125A/127H, 116A/H) for the refoaming job. He then followed up with post-purchase support and immediate replies to a few questions that I had. Since the surrounds for the 125A are a tad smaller than the L56 woofer dimensions, I was hesitant at first. Scott’s post and Rick’s ‘Beta’ surround, as well as GordonW’s post gave me the confidence to do this job to the degree of success that I achieved.
I now have two vintage woofers that sound and appear to be brand new. If I didn’t know that these were refoamed, I wouldn’t be able to tell, sound-wise and appearance-wise. The job went perfectly.
In a nutshell, with some gentle stretching and patience, the 125A kit works beautifully for the L56 woofers (and any other speakers that use the L56 woofers).
I took pictures of all steps from start to finish, if anybody is interested.
thx for letting us know about your source & success, ordering stuff righht now
oh and a question, what to do with expired glue from genuine JBL cone kit? I have one 2007, and another 2008 feb..
Golly, I'm floored! (speechless)
I am so glad everything worked out for you! Please know, that with a little patience, anything can be achieved!
Please post the pictures, if you choose. I am sure someone else will benefit from them. The moderators will make sure they are in the right catagory.
Question to the Moderators:
Is there a catagory of recone, refoam, rediaphram, resetting polepieces... anywhere here on LH where forumites can learn from others. A basic how-to for these wonderful tranducers and their supporting parts?
Regarding tubes of glue. I throw them in a box with all of my reconing stuff, and will use what ever tube is not dried out. No reason to chuck it if it is not all dried out. I use it on other electronic repairs.
I even convinced Lisa to ALWAYS carry a small roll of solder in her handbag at all times.You never know when you might need it!
Bottom line, I am very humbled to be thanked so beautifully for something that is so basic in my life.
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC˛ ±3db
So, here’s how it went:
After getting this pair of L56’s I realized that the original surrounds were brittle and one had developed a hairline crack in it (which quickly spread 1/2way around the roll).
Apparently the surrounds in these woofers is different from many in that it’s more of a non-porous rubber material than a foam. Since the material had hardened from age considerably, I’m guessing that even if the surround weren’t yet cracked, woofer performance would have been hampered due to lack of flexibility of the surround. Anyway, the second was obviously on the way out as well.
In doing a search here in the forum for suitable surrounds; and seeing that Rick was recommended as a good source for resto. surrounds in this forum, I looked at his auctions in eBay. Rick didn’t have any specific surrounds for the L56.
Scott and Gordon had mentioned their success in refoaming L56 woofers using the surrounds for 125A woofers, and I asked Rick about that. Being as that he had never done an L56 refoam, he was hesitant to sell me 125A surrounds with an endorsement that they’d work in my case. What he offered was to send me a test surround – free of charge - to try the fit before buying his 125A kit. I took him up on his generous offer, and tried the test surround.
Using Scott’s post as a reference, I warmed it and gently stretched it by putting the material between my thumb and fist.
I worked around the entire surround, and test fit it to see if it was getting close to the right diameter. It still wasn’t quite big enough, so another stretch around the diameter, and the second time was a charm.
One thing that I noticed about these foam surrounds is that they have a memory and a moderate stretch will return back to the original diameter in a day or so. That’s a good thing. So the stretch should be done just prior to the install/glue.
After buying the complete kit and following Rick’s directions (which are very well written, clear and very easy to follow), I removed as much of the old surround as I could, using a sharp utility knife, a good, clear work area, plenty of light and patience. It’s best to start by freeing the cone from the old surround. This way, the remainder of the surround can be cut away without disturbing the cone and risking damaging the coil.
A couple things to mention: the trim ring/gasket on these woofers is in 4 pieces. It’s the first thing you’ll remove and the last to re-install. If you’re concerned about aesthetics of your speakers, take your time in removing these. They’re soft and easy to damage, so use a new, sharp utility knife so as not to shred them up too much, because you’ll need to reuse them. Secondly, the portion of the original surround that’s adhered to the underside of the cone was glued in so well, and was still strong and very evenly adhered, that trying to remove it would have been a mistake. Figuring that the adhesive has held up for 20+ years, I can’t see it failing anytime soon. The remainder of the surround was smooth, very even and very secure. With a quick consult w/Rick, I decided to leave it and glue directly to it.
The adhesive that Rick provides w/his kit works well and 10+/- Q-Tips help to get it spread evenly throughout the job. This adhesive looks much like Elmer’s glue, and has a very workable setup time. It’s easy to work with. Plus it dries clear so any visible glue isn’t too apparent when it dries.
Rick includes a 30 second test-tone CD that puts a low frequency through the woofer to helps to align/seat the voicecoil and test for misalignment. Following the instructions, the cone bounced silently, indicating that it was properly aligned. This is a nice test for peace of mind – allowing for adjustment prior to the adhesive setting up if needed.
All in all, this was a huge success in my mind, figuring that this was my first attempt at anything like this.
<<<(the glue hadn't fully cured in this pic.)
I was able to remove the old Lansalloy by soaking it with a Q-TIP wetted with MEK. I used a fresh x-acto blade to angle cut through the old surround down to the cone, then gently started to work under it and peel off the surround.
That sucker was stuck on pretty good, even with the MEK soaking (not so much it ran into the cone) but I was able to peel the entire surround off in pretty much one piece. Any time it started to resist, I just applied a little more MEK and used A LOT of patience. The old glue was probably well broken down as the Aquaplas underneath was yellowed and likely gave up the fight due to that sparkly coating the older Aquaplas'd drivers seem to have.
I had one or two tiny spots of the Aquaplas lift off with the surround, but after the full cleanup, sealed the offending areas with Rick's glue. There's one spot still showing that I'll touch up with a paint pen or whatever I can figure out. The cones aren't as yellow as the shots would indicate. I like to avoid the flash and let the DSLR do it's thing, but I had the white balance stepped down a bit from taking some black gear shots.
The trim ring was another story altogether. What a bugger! The old yellow, rubbery glue was a biotch to get off using liberal amounts of MEK, scraping, rubbing and ragging. The glue was much easier to get off the frame using MEK and my flat x-acto chisel blade.
First up, the test fit using the retainer ring and Rick's 30Hz test CD. Nearly a perfect center, but the surrounds seem maybe 1/16 too small on the outer dia. at rest.
I applied the glue to the cone first in a continuous bead, then spread it using a small artists brush with my finger propped against the frame and turning the driver to get a nice even curve.
While it tacked up, I attacked the new surround using the same method. I notice the glue sets up a little quicker on the surround so doing only 1/4 or 1/3 at a time - lay a bead, spread, repeat seemed to work best to get edge-edge even and smooth coverage.
I laid the surround into position and carefully started to apply even pressure around the edge, ensuring the surround edge and concentric rings on the cone are nicely aligned, increasing pressure and area, always supporting the back of the cone with my finger(s) as I worked my way around several times. I did not have a turntable, but always protect the backs with blue painters tape, and this moves rather well on a smooth work surface. Once satisfied it was perfectly centered and stuck, I moved onto the next one and repeated the process.
After leaving them to setup for several hours, I laid down a bead of glue on the frame and spread it out a little. I prefer this to a single bead or I tend to apply too much and get spotty drips. Performed the 30Hz centering procedure and then installing the ring to hold it in place (important not to use so much glue it will seep out and stick the ring.) After another 15 mins or so to let it stick up well, I carefully pulled the ring and applied a bead of glue where the horiz and vert of the frame meet each other and pressed the ring back into place, cleaning up any excess that oozed out with my brush and a wet rag. Again, a rinse and repeat on the other and they're done!
Sorry I didn't take any WIP pics... Here's the finished product before remounting in the cabs. LH limits the pic attachment size but the hi-res is avail if anyone would like them via e-mail, just PM me. These low-res, low quality pics don't do them justice.
They sound significantly better. They do "play to the knees" to quote Zilch, but I'm fairly impressed with the bass response of these hooked up to an old Yamaha CR-1020 receiver. The LE20 certainly need help... But that's another project.
And as we all know, this driver had the Lansalloy attached to the front of the cone, and the cosmetic preference should be to do the same with the refoam.
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