voice coil repair

hay guys! i am new around here, and in the middle of a project. hoping you guys might have some advice.

i am trying to repair 2 blown 12" subs from my car. i blew them when i bought a new car. i had to build a new box (or boxes). and when i had finished the first one i couldn't wait so i installed one of the subs and my amp. the amp (1200w) blew up the single sub before i could finish the second box. so i put the other one in and it also got blown up.

that was a few years ago now, but i have been so busy with other stuff i didn't have time to look at them. well i have some time now and have been doing lots of research. this will be my first attempt at any kind of speaker repair. i should add that i am a certified electronic technician. so i know my way around some stuff, just never done any speakers.


so from my research i have found the proper "magnet wire" for the voice coil. i have dismantled the speaker. and removed the old coil. i am ready to wrap the new one. i have a few ideas on what to use as a spindle to support the center while i wrap the new coil. but i would like any and all suggestions. also i am trying to figure out what kind of glue to use to attach it to the center. again looking for input.

heres some pics of where im at.

pic of subs in box. keep in mind this is right after i pulled it out of the basement, where it sat for a few years.



one of the subs



opend up



the voice coil removed.



now i know they are not the best speakers in the world. and most people would just buy some new ones but i want to fix them for several reasons.

even tho they were under $150 new with the box, i still think they sounded good, and i also think they are a good quality speaker.

they were the first set i ever bought, and they were installed in the first car i ever owned.

i still think they look FANTASTIC. these things are really beautiful in real life, the pictures dont do them justice. and the finish, matches my computer. which is another one of my babies! (my computer if you are interested. http://s168.photobucket.com/albums/u166/Zygoat_D/comp/)

last i want to learn more about how all of it works!

hope this wasn't too long of a read. and i appreciate any input you guys have.

Welcome to AK Zygoat!

That looks like an interesting project. I don't have the expertise to offer any help, but I wish you luck with it.

Tell us your ideas on how you are going to wrap it. They are not speakers that I'd be putting a lot of effort into, but at the same time, it's a great project, IMO. The woofers aren't going to put you out a lot of money if things go awry and you will get a better understanding of how it works in the process.
:thmbsp:

Whatever you can get that fits and is round will work as a former. You just have to make sure it's solid enough that wrapping the wire won't deform it and take your coil out of round. Last time I was on a coil line we used custom turned aluminum mandrils.

Wrapping will be very time consuming as you have to make sure each turn lays properly. In the industry the winders use a counter and high speed motor to get the number of turns right and there is a keeper to hold the wire in place. By hand it's just slow. Did you check to see if the coil you took off the former was 2 or 4 layer? A lot of car type subs use 4 layer for more mass.

As for adhesive, I'm not really sure what we used as I didn't spend much time down there. It was heat curing and we had a cyclic oven to cook them but I don't know what the active ingredients were. Application was done by running the wire through a set of sponges damped with the adhesive just before winding. I'll have to ask by buddies back at the plant what it is.

Some bad news...in order to get the whole assembly centered once you get it rewound (assuming you can get it done), you'll have to cut out the dust cap to put shims in around the core. Some people refoam without cutting the cap and just use a low frequency test tone. That won't work in your case because the spider is also loose. You'll have to get everything centered up and glue it at once. Depending on what adhesive was used on that cap you might be able to use an exacto knife and cut through the glue without killing the cap. Hope so.

Ray

well guys thanks for all the info. much appreciated.

ideas for wrapping.

first is to custom turn an aluminum mandrel on a lathe.

the second was to use an old toilet paper roll (the cardboard) as a base and then apply layers of fiberglass on top to get the correct thickness. the fiberglass and resin can be had at local auto parts stores for cheap.

it was a 4 layer. i am sure it will take quite a while but thats fine with me. its a labor of love anyhow. still looking for the proper adhesive so id appreciate anything you can find out. (at this point i am actually kinda waiting on that).

i knew the center cap might be an issue. all the reading i have done has told me that you have to take it off to center it as you say. i am probably going to sound crazy here, but i think i might just give it a whirl free hand. i have been building stuff since i was old enough to hold a tool, and i am pretty good by now. and worst case, i just have to cut it back off and do it the right way.

near as i can tell all of the adhesives they use look alot like black rtv silicone. i dont know for sure if thats what it is, but its the closest thing i know of.

Zygoat said:

it was a 4 layer. i am sure it will take quite a while but thats fine with me. its a labor of love anyhow. still looking for the proper adhesive so id appreciate anything you can find out. (at this point i am actually kinda waiting on that).

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Email has been sent. I'll let you know what I find out.

i knew the center cap might be an issue. all the reading i have done has told me that you have to take it off to center it as you say. i am probably going to sound crazy here, but i think i might just give it a whirl free hand. i have been building stuff since i was old enough to hold a tool, and i am pretty good by now. and worst case, i just have to cut it back off and do it the right way.

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Your choice. Think about this...if you screw up cutting the cap out you risk damaging the dustcap. If you glue it together, get a rub and have to cut it open again you risk damaging the surround and the spider.

near as i can tell all of the adhesives they use look alot like black rtv silicone. i dont know for sure if thats what it is, but its the closest thing i know of.

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If you mean for gluing the dustcap in, then that's probably pretty close. Worst case would be that they used CA (superglue) for a quick set. The black stuff comes off ok.

thanks for your help.


i was referring to the stuff that glued the surround and spider to the frame.

and i know about ca, long story short got some in my eye. i blinked when it shot in there and that was all the time required to glue my eye shut. i had to rip it open with my and. ended up having to wear an ye patch for a week. and put antibiotics in my eye (was alot like petroleum jelly). not fun. ive also glued fingers together and to other things a few times. (i work with it alot)

http://www.repairfaq.org/REPAIR/F_Speaker.html

http://www.mwaspeakerparts.com/

thanks for the links, the first one ha some good info.

the second one is for businesses only. i had come acrossed it before (in my research) but i am not a business.

the first page referred to "q dope" anybody know what that is? also they said it is not as good as the original epoxy that the factory used. anybody know of a good substitute for the original epoxy? i know ray is looking in to it for me.

I use the "Service Cement" part no 10-302, to fix a voice coil to the cone. It still work.

http://www.gcelectronics.com/order/SubCatPDF/adhesives Epoxy cements 50-53.pdf

Wow. I'd like to see some pictures of this project if it works out... I was thinking www.partsexpress.com for some replacements.

Here's the reply from my buddy:

I was told the glue we coat the wire with is our one secret.


He should buy some "bondable" wire that is pre-coated and he can wet
wind it. You re-activate it with either alcohol or acetone.

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If you've already got the wire then I guess this won't help much.

Ray

thanks ecluser, ill look into that stuff.


i do already have the magnet wire so, that is a no go, thanks anyway ray.

I don't know if I missed it but what are you using for the former? It looks like the old one is warped.

I'm wondering also where you got the coil wire from?

i looked into that stuff from gc electronics. man thats pricey stuff $15+ for 2 oz.

i will either be using fiberglass reinforced....toilet paper tube. or a custom made mandrel out of aluminum. probably the latter. i already started work on it.

i got the wire from bulkwire.com. looks to be good stuff, especially for the price.