When the magnet has shifted

[Lee in Montreal]

Well, out of the four 2225h baskets I bought, one had a shifted magnet. It was very difficult to remove the coil. So, I took it apart (what do I have to loose anyway). I now have two parts. The magnet itself, and the basket with the round aluminum support in which the basket is screwed. On the magnet's face, there are three holes. Great. Must be for centering. On the back of the round aluminum plate, nothing. Just some grey coating. Do't tell me the magnet and support plate were centered at the factory with a gig, and then glued together. And that if the glue dries up, the magnet shifts. So does it mean I have to machine a round plastic donut myself to use as a centerig tool and then glue the assembly together? Then what type of "glue" should I use? OR I might just as well machine three holes on the backing plate and make 3 dowel pins to center the parts together.

Ninja edit. Found the following thread. Yes. Just glued. Therefore I now need to samd the old glue. Determined the gap by measuring with a digital caliper the inner and outer diameters (98.50mm and 101.45 - meaning 1.475mm gap most likely made from a strip of teflon). Now looking for the proper type of adhesive.

[Eaulive]

Well, out of the four 2225h baskets I bought, one had a shifted magnet. It was very difficult to remove the coil. So, I took it apart (what do I have to loose anyway). I now have two parts. The magnet itself, and the basket with the round aluminum support in which the basket is screwed. On the magnet's face, there are three holes. Great. Must be for centering. On the back of the round aluminum plate, nothing. Just some grey coating. Do't tell me the magnet and support plate were centered at the factory with a gig, and then glued together. And that if the glue dries up, the magnet shifts. So does it mean I have to machine a round plastic donut myself to use as a centerig tool and then glue the assembly together? Then what type of "glue" should I use? OR I might just as well machine three holes on the backing plate and make 3 dowel pins to center the parts together.

Ninja edit. Found the following thread. Yes. Just glued. Therefore I now need to samd the old glue. Determine the gap by measuring with a digital caliper the inner and outer diameters. Now looking for the proper type of adhesive.

The problem is that the ferrite, plate and pole piece are assembled and glued before being magnetized.
With the magnet at it's full strength, it's gonna be very difficult to center it properly, and those drivers have a very small tolerance for errors...

I don't want to rain on your parade, but I would not risk putting a new cone in this frame now.
Maybe some shop could de-magnetize it and re-magnetize after you fix it, it's all a matter of cost.

[rlsound]

Lee,

There's a shop here in Vancouver ( http://vancouveraudiospeakerclinic.com/vasc7.html )

that fixes this! Not sure if it's worth the shipping to Vancouver, but if you want to save the basket....

[Lee in Montreal]

Maybe some shop could de-magnetize it and re-magnetize after you fix it, it's all a matter of cost.

I will have an aluminum ring machined. I will loan it if needed. The sleeve/ring will be long enough so that the round plate is easy to slide on from a 4" distance where the magnetic field is weaker. Tolerance will be within 0.05mm.

[Eaulive]

I will have an aluminum ring machined. I will loan it if needed. The sleeve/ring will be long enough so that the round plate is easy to slide on from a 4" distance where the magnetic field is weaker. Tolerance will be within 0.05mm.

That could work, but will you be able to remove it when the strengh of the magnet will close the gap on it?

[Lee in Montreal]

I inspected closely the magnet and used a dye to check for cracks. Surely there are three cracks in the magnet. It most likely has been hit bad, which could explain the separation and the magnet shift. So this one is most likely toast. :(

Lee

[subwoof]

The percentage is about right. Unless they are shipped in a REAL factory box designed for a 15" heavy speaker, 1 in 4 die an unnatural death.

I remove the backplate, untwist a section of 1/2 manila rope and tie the ends into the 3 magnet holes.

Then give it to a fab / carpenter shop as a magnetic sweep and collect a favor owed.

btw it is NOT recommended to attempt an align/remag on these ceramics due to occasional explosions. I guess the little things do matter.

:cheers:

[Eaulive]

btw it is NOT recommended to attempt an align/remag on these ceramics due to occasional explosions. I guess the little things do matter.
:cheers:

Explosions? :blink: :dont-know:

[grumpy]

...think shattering/brittle ceramic and high velocity shards... Explosion? close enough.

[Eaulive]

...think shattering/brittle ceramic and high velocity shards... Explosion? close enough.

Ok, possible, but I guess it's like everything, Use the right machinery in a safe environment and wear safety goggles :applaud: