JL Audio 12W7 magnet "core" dislodged

[StarMan7]

Hello to all; noobi on the loose.
I bought a closure, real, I mean REAL cheap knowing the speaker was toast. I am not a audiophile and I knew not what a JL Audio 12" W7-3 was till I got it home and opened it. I know someone who reconed a mid-range once so I thought I might give it a try. I thought I might watch youtubes to figure out how to proceed, but this issue was not addressed in any vids and now I don't know if I can proceed. The cone would not budge, the surround was torn, but other than that, no prob, right. After gentle persuasion failed to extract the voice coil from the frame/motor or whatever the term, I cut the spider and gave a mighty tug on the cone with all my might and finally got it out so I could see what was wrong. The center "plug" that the coil slides over is up against the magnet! That is why the coil was impossible to remove. Is this even repairable?
Please be kind, I am a noob.
Jim@MilkyWay

 

[shadyJ]

It sounds like the pole piece has been banged out of alignment. Not sure how that could happen. Yeah, it sounds like that driver is toast, since the motor structure is damaged. That is a shame, the W7 is a nice driver.

 

[StarMan7]

Thanks ShadyJ for the reply. This is the first forum I have joined but I may not be on the right page/site. I need a technical/repair type forum in my case, as opposed to a forum that discusses equipment matching and selection. Do you subscribe to any other forum? I am interested in solving/resolving my dalima because, if I am not mistaken, these things have to be assembled, new at a factory, so there must be a way to re-center the pole piece.

 

[annunaki]

If the pole piece is not aligned it tells me that driver has had some serious physical abuse. Guessing it was dropped. If the pole is out of alignment the motor is junk, you will not be able to repair it.

 

[TLS Guy]

Thanks ShadyJ for the reply. This is the first forum I have joined but I may not be on the right page/site. I need a technical/repair type forum in my case, as opposed to a forum that discusses equipment matching and selection. Do you subscribe to any other forum? I am interested in solving/resolving my dalima because, if I am not mistaken, these things have to be assembled, new at a factory, so there must be a way to re-center the pole piece.

We do have people here who have a lot of experience repairing drivers including myself.

You have a very difficult problem. Attempts to repair this driver will probably fail for multiple reasons.

The driver has been damaged by being dropped.

Magnets are actually usually glued on using loudspeaker magnet glue. The fact that the magnet has shifted means that you can probably break the magnet loose.

Bolt the driver to a large heavy board and clout the magnet with a large heavy impact soft hammer.

If you can't break the magnet loose it is game over, same if it distorts the chassis.

If you break it loose, you will need to make a jig with plastic pipe to realign the magnet and glue it back in place.

Now the next problem is that JL drivers are not built like others and this makes assembly difficult. JL do not provide parts.

Now usually a new cone comes with attached VC, JL audio drivers do not. So you need a VC on the former. There are eBay sellers, how good the products are I don't know. You will need a generic spider of the same dimension with the lead in wires to solder to the VC. The spider will almost certainly change the Thiel/Small parameters, so you won't have the same driver when you are done. So you will have to measure them and recalculate box and port dimensions.

Now you will need to make shims to center the VC in the gap after gluing the spider to the VC with loudspeaker glue. You will need to glue the spider to the chassis with the same glue. Now you need to have a new cone with surround. Again there are eBay sellers. Now you need to glue the cone to the VC collar with loudspeaker glue.

Now glue the surround to the chassis with loudspeaker glue and let the glue cure for at least 24 hours. Hopefully you will not have gap rub.

Now measure the T/S parameter to see if you have a driver that is any good.

Even if you are experienced the chances of a successful repair are not good. If you have not rebuilt a driver before, your chances of success are slim to none. You have nothing to loose so if you want to invest the time and money go ahead.

 

[StarMan7]

....Magnets are actually usually glued on using loudspeaker magnet glue. The fact that the magnet has shifted means that you can probably break the magnet loose....

Thanks for the reply TLS Guy. I am pretty sure it will be a losing proposition to invest time and money into. Just to be clear, the magnet(s) has not shifted; the pole piece/plug in the center is the issue. The only thing I might be willing to try is to clamp the frame down and see if the pole piece can be pressed out from the back. If I can push it out, then I'll see what is next.

 

[TLS Guy]

No the magnet has shifted. The pole piece is one pole of the magnet.

Look at this diagram.

So you can see the bottom/rear plate has shifted with respect to the top/front plate. So since opposite poles attract, the center pole is held fast against the front pole with extreme magnetic force. So the south pole has actually become detached from the North pole and is held by magnetic force. If it were not for the opposite poles attracting then the back of the magnet would have fallen off.

 

[StarMan7]

No the magnet has shifted. The pole piece is one pole of the magnet....

Thanks TLS Guy! And please excuse.
I can't believe, after reading your post that I failed to investigate that before clicking send. I laid there and thought about it after I logged off and hit the sack. Everything is not as it seems to a noobi! I will try to open my eyes and ears before opening my trap for future responses.

 

[TLS Guy]

Thanks TLS Guy! And please excuse.
I can't believe, after reading your post that I failed to investigate that before clicking send. I laid there and thought about it after I logged off and hit the sack. Everything is not as it seems to a noobi! I will try to open my eyes and ears before opening my trap for future responses.

Not to worry. That was a teachable moment. We are used to that here. You do seem teachable though. You now know why you had to tug on that cone with all your might!

Unfortunately this is a next to impossible task. The other thing I should have mentioned is that the magnets are energized after assembly. In all honesty that chassis is a bin job.

 

[StarMan7]

Not to worry. That was a teachable moment...., .... In all honesty that chassis is a bin job.

Done; and thanks again to you and all the others for taking time/interest to respond. I also clicked on the hyper to your studio and looked at all the pics. Nice telephone, man! At least that's one component I understand.
Umm, is there any justification for buying a like speaker to go in the sub box? I don't know what I could get one for, used. If I could get a good speaker I wonder if I could hope to resale it and get my money out of the deal and have some fun learning.
Perseid meteor shower tonight, guys/gals, and no moon! Might be a good show after midnight.
Jim@MilkyWay

 

[TLS Guy]

Done; and thanks again to you and all the others for taking time/interest to respond. I also clicked on the hyper to your studio and looked at all the pics. Nice telephone, man! At least that's one component I understand.
Umm, is there any justification for buying a like speaker to go in the sub box? I don't know what I could get one for, used. If I could get a good speaker I wonder if I could hope to resale it and get my money out of the deal and have some fun learning.
Perseid meteor shower tonight, guys/gals, and no moon! Might be a good show after midnight.
Jim@MilkyWay

The Minnesota sky is full of smoke, and has been for days from the fires in BC and Alberta. So it is a bust here.

I really can't answer your question, as I don't know the particulars of the box. If it is a box built from the JL website then the designs are almost all wrong with the boxes seriously undersized. The reason is that the JL product line has been based on in car audio.

So the box dimensions would be critical. The design of the box is critical and determined by the Thiel/Small parameters of the driver.

Assuming you could find a driver, you would have a DIY sub, and properly done there is nothing wrong with that. It is just hard to realize much cash from the sale of them. Basically due to inexperience you have paid money for a sub driver worth only the scrap metal value which is pennies, if that. I can not comment on the value of the box as I have no idea what it is. For instance I have no idea of the box dimensions, and if it is sealed or ported. If ported I have no idea how it is ported. In addition I have no idea of the build quality and mechanical integrity of the structure.

I have a feeling though you are itching for a DIY project. More likely than not this project is unlikely to be suitable. But I need the box details and pictures to give you an informed opinion.