So - yesterday morning I removed the 112A midbass drivers from the cabinets. After work I peeled off the "O-rings" that held the surrounds in place. I had already ordered and received the Surround kits from Rick Cobb, and have done many larger JBL surrounds in the past, so I figured it would be no big deal. I clean the bad surrounds and glue with MEK, which need LOTS of venting as its quite toxic stuff. I usually do the clean ups on our back porch, which is an open, screened in space. Its December, and its cold - about 30 degrees when I started to rub off the old surrounds, scrape the frames and wipe the surfaces thoroughly with MEK. Its messy, the MEK evaporates fast, and IT WAS COLD!
Once cleaned, I was eager to get back inside to do the glue work - no real fumes from that. I brought the "cores" in, popped them on my bench, and dropped the new surrounds in place just to confirm they were a good fit. I laid a clean bead of the glue on the inner edge of one of the new surrounds, slipped it around the cone, and pushed it against the back of the speaker cone. I went around it a couple of times to be sure it was fitted as the glue set up. Once that was done I started with the second speaker. But as I was working it around the cone I notice that moving the cone made a rustling sound. The Other One had NOT made any sounds and had floated free. This one rubbed and did not move freely. OMG - one driver is bad - and these drivers were rare when new and have been out of production for years! Parts have been NLA (No Longer Available) for years as well. Unobtainium!
Picture from yesterday, before I cleaned up the old surrounds -
amazing 8 inch Alnico drivers with 3 inch voice coils! Vintage JBL quality.
Emma suggested i make a video to show the seller that there was a problem, so I grabbed the camera as she gently moved the speaker cones.
Pretty easy to hear the rub
https://www.youtube.com/watch?v=69_mDMH0gSI
The seller refunded some of my money so I could get the driver reconed - (actually, if I go that route, I'd get both of them reconed so they stay matched)
- but for now, I'm taking a couple days off for the holiday and will consider other possibilities. I did post a WTB ad in the marketplace, if anyone has a working spare 112A.
And - I dragged my vaccuum upstairs and tried to pull out the pushed in silver domes on the 066 tweeters - no success so far -
it's very stiff and feels more like a metal foil of some kind, instead of metallized silk as I expected.
But I'll haul the shop vac up in a couple days and try again. Maybe heat the domes up with a blow dryer (?) so they can pop free easier.
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Originally Posted by hjames
