Speaker Repair Voice Coil Spider

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I just got ahold of some pretty wracked woofers. They are 10" alnicos by Altec. The braided leads to the contact points on the cone were disconnected. The cones were stuck in a retracted position. I pulled off the cone to reveal the voice coil, the cone came right off. The inner paper of the voice coil is warped due to heat and the cone will not move up in down in the magnet slot. The spider is now permanently misshapen. Both woofers are in this condition. The coils seem intact, though, they read 7.2 DC ohms. Is it just a matter of finding a coil of the proper diameter for the slot in the magnet? I see matelectronics has some voice coils, but I doubt if any generic would work, doesn't it have to be custom for a particular woofer? Pretty close, though at 1.5". They also have spiders, same with those, don't they need to be the exact right shape? The ones on the woofers are 106mm and theirs are 110mm, would work, OD at least. Could I just cut off the cone, glue on a new spider and voice coil and resume rocking? What kind of glue? Help me here, I've re-surrounded a couple of dozen speakers, want to expand my expertise. Willing to break things along the way if necessary...
 
diyAudio Moderator Emeritus
Joined 2001
On the issue of whether those voice coils would work in your Altec speakers, because the Altec speakers seem to require a 1.5" voice coil and that is what matelectronics is selling:

I don't know. However, I would point out that the clearance between a voice coil and the pole piece is something like five thousandths of an inch, so the voice coil has to be exact.

I do not know whether American manufacturers make their 1.5" voice coil exactly 1.5", or if there is some slight variation between manufacturers and they are all called 1.5 inch voice coils for the sake of convenience. I would assume that foreign manufacturers use metric sizes so I doubt if the voice coils would fit with the precision necessary.

Perhaps someone who has tried to transfer a voice coil from one make of speaker to another could enlighten us. All I can say is that if you were planning to buy some other stuff from matelectronics, (their minimum order is $25), go ahead and order a pair of 1.5 inch voice coils and see if they fit. I don't know if they will or not, but at the price nobody can call you nuts for trying. :)
 
diyAudio Moderator Emeritus
Joined 2001
On the issue of spiders, now we have a different story. The spider determines the stiffness of the suspension, much much more than the surround. I do believe the spiders matelectronics sell would fit and work in your Altecs, but the parameters of the speaker will likely be different from the original manufacturer's. But there is no reason they should not work.

One thing about the Alnico magnets, though. I believe over time they lose much of their strength. Perhaps there is some shop around that might charge them up for you-it couldn't hurt to ask.
 
"On the issue of spiders, now we have a different story. The spider determines the stiffness of the suspension, much much more than the surround."

Not always. My 15" Altecs have more spring in the surround than the spider. The surrounds are shot. The cone doesn't hang on the spider,
it falls to the shelf it is sitting on.

Great Plains Audio may be able to help out with vcs and spiders.

Good luck.

Geoff.

edit: The magnets should be OK if they haven't been dismantled. The fact they have alnico magnets means they are worth repairing with the correct parts.
 
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