Hi, I recently reconed a set of 2245's. Looks like I did not seat one of the spyders in the glue well enough and it came apart. When it did, it bent/cracked a 1 1/2" section of the cone along the surround. I suppose I'll have to try and reglue it and hope I can keep the voice coil centered, but before I do, I thought I would solicit advice about it and the cone.
Mike
I would (not seeing the damage of course) cut the dome off carefully, and get the VC shimmed and centered in the gap. Then with whole cone assembly excurted outwards to gain access to the spider/glue joint, apply a bead of glue to both mating surfaces, let it tack up then gently press the cone down into it. The jbl glue I have used in the past needs a couple of minutes tack time, and then it adheres on contact. (I believe that is, in fact, a contact cement and behaves the same) Remove shims, test with sine wave test tone sweep and if satisfactory reglue dome.
I have done this repair before, and if you catch the lifted spider glue joint in time, the rubbing of the VC winding may still be okay; but if the uncentered VC rubbing in the gap was too intense, the protective enamel coating on the VC winding will be compromised electrically. Then its recone time.
Scotty.
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC² ±3db
Originally Posted by SMKSoundPro
Thanks Scotty, Just like replacing a surround for shimming! I looked at the voicecoil and there is a pretty good blackish rub on it. Remind me, what indication will there be if the voicecoil is damaged. I don't have a test tone, so i will have to make due with music.
Thanks, Mike
Evidence of blackish rub is not good. It indicates the voice coil rubbing against the top plate, and if it has abraded through the protective enamel coating on the individual strands of wire that are coiled to make up the voice coil. I would use a good digital test meter and do a simple test for DC resistance of the voice coil at rest. The reading should be 5.8ohms and here is the link: http://www.audioheritage.org/vbullet...hp?10654-2245H
If the resistance is very close, then I would carefully lift the cone and apply some clear nail polish to the voice coil windings in an attempt to seal the copper wire.
Then your back to cutting off the dome, shim the voice coil perfectly centered, and reglue the spider and when the glue tacks up, drop the cone straight down, let dry, remove shims, replace dome....
I know there are cd's available with different test tones, and what you're looking for is a simple audio sweep from 20hz up to about 500hz. Play the cd and make sure the there is no rubbing in the vc, or mechanical buzzing from the 2245, but be careful not have your volume set too loud. Remember the driver is sitting on the bench face up, the vent is probably blocked and there is no baffle board working for you. (I melted a smaller vc on a refoam job by pumping to large a voltage into it, and now it is fubar.) Just make sure that the tone is clean and clear.
The dc resistance test seems like your best evaluation of the condition of the vc at this point. If you visually inspect a portion of the vc and don't see any excessive burning of the coil, or blistering of the vc coatings, or burned smell...you might be just fine.
Scotty.
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC² ±3db
you may be able to find a test tone download online, if you so desire...
just burn it to a CD after download, if you can't feed files into your system
You may choose to contact a verified JBL Service Center and have this driver reconed by a pro. There are many on here and their knowledge, experience and wisdom may save you allot of grief in the long run. Without seeing your driver, I can only offer some insight into your particular problem and its remedy. The 2245 is a fantastic extended low frequency driver and worth every penny of the JBL Service Center's recone cost. They will only go up in value, IMHO, and only if reconed with genuine JBL parts by a pro.
Scotty.
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC² ±3db
You may find yourself behind the frame of a large JBL subwoofer.
You may ask yourself, well, how did I get here?
You may ask yourself, where is that large JBL subwoofer?
You may ask yourself, where does that voicecoil lead go?
You may say to yourself, my God, what have I done?
(apologies to Mr. Byrne, et al)
Yeah well, that's just, ya know, like, your opinion, man.
Thanks for the flashback
One step above: "Two Tin Cans and a String!"
Longtime Alaskan Low-Fi Guy - E=MC² ±3db
Good one, thanks Grumpy. Neither here nor there but, if I can be of any help to others never do what I did.... I let my nephew (19) help me recone the set because I thought it would be a good bonding experience. That's the spyder that came apart. it was also cocked off center a good inch making soldering the wires fun. I'm not blaming mind you, I am just saying $150 lesson. My woofer on the other hand is holding up fine
Or not!: I thought it would be a good bonding experience.
If we knew what the hell we were doing, we wouldn't call it research would we.
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