PDA

View Full Version : Coil repair



hardtime
08-24-2008, 05:57 PM
Can an open voice coil be replace on an otherwise good cone?
I have a JBL 122 that I would like to repair.
It goes in L166.
Thanks

speakerex
08-26-2008, 11:08 AM
Can an open voice coil be replace on an otherwise good cone?
I have a JBL 122 that I would like to repair.
It goes in L166.
Thanks

The voice coil will be replaced during the reconing process. Reconing replaces all the moving parts in the speaker frame: voice coil, spider, cone, surround, dustcap, leads and sometimes gaskets if applicable. Sometimes with certain hard to find or odd shape/size cones, an attempt is made to recoil only. It is much harder to do than a complete recone because the original cone must be saved and the orig adhesives removed, all without damaging the cone. Usually the spider will be replaced with the voice coil because it is almost impossible to save one.
Options are aftermarket recones or factory JBL recones. I can give you more info if you need it. cathy@speakerex.com

hardtime
08-27-2008, 06:48 PM
The voice coil will be replaced during the reconing process. Reconing replaces all the moving parts in the speaker frame: voice coil, spider, cone, surround, dustcap, leads and sometimes gaskets if applicable. Sometimes with certain hard to find or odd shape/size cones, an attempt is made to recoil only. It is much harder to do than a complete recone because the original cone must be saved and the orig adhesives removed, all without damaging the cone. Usually the spider will be replaced with the voice coil because it is almost impossible to save one.
Options are aftermarket recones or factory JBL recones. I can give you more info if you need it. cathy@speakerex.com
Thank you for your response.
The reason for the request is an attempt to salvage the original 122 cone with its aquaplas. I thought the replacement is a lighter assembly and of course would change a lot of numbers.
Do you know where an exact replacement can be found?
Thanks again.

speakerex
08-28-2008, 01:53 PM
Thank you for your response.
The reason for the request is an attempt to salvage the original 122 cone with its aquaplas. I thought the replacement is a lighter assembly and of course would change a lot of numbers.
Do you know where an exact replacement can be found?
Thanks again.

I spent alot of time today trying to determine the quality of the aquaplas on the current recone kits. Originally (maybe 30 + years ago) the L166 woofers used a C8R122 recone kit. For at least the last 20 years, the C8R129H recone kit has been used. It is possible that the aquaplas on the 122 kit was different from the 129 kit but I can neither confirm or deny this. I can tell you that in order to replace the voice coil, the woofers should be reconed. If they are reconed with factory JBL recone parts, then they are returned to current JBL standards. Actually, I'd be surprised if more than 1-2% of the population could hear the difference between two woofers with the different kits in them even if in an anechoic chamber. I hope this helps you with your decision. cathy@speakerex.com

ReEdger
08-29-2008, 06:19 PM
I replace the voice coils ONLY on many JBL speakers because the original cones are unobtainable.

So, the short answer is yes. You can replace just the vc. It's a bit of a ticklish procedure but I've done it many many times.

If someone convinces you to go with a total recone on your speaker, well, you can offset the cost by selling me your old cone!

I have an L166 pre Horizon that has a bent and messed up cone, but the vc is still good.

Shoot me a PM

GordonW
08-30-2008, 06:24 AM
I can tell you- I've weighed the assemblies, and the 122A is heavier than the 129H assembly. Can't remember the exact figures, but it was by around 10 grams or so... that order of magnitude difference.

So, I would agree with keeping the original cone... especially when high-quality edge-wound coils are now available in the aftermarket. In the old days, it was a choice between a factory kit (with a proper edge-wound coil) or an aftermarket kit with a round-wire coil... this is no longer a hard-and-fast limitation...

Regards,
Gordon.