Displaced Magnet

[Surtsey]

I have a subwoofer where the magnet is no longer square to the cradle. Obviously the voice coil rubs against it when the unit is driven.


(1) How could this happen?

(2) Can it be fixed without destroying the cone?

I've no idea how to upload an attachment on this site otherwise I'd post a pic.

 

[weltersys]

(1) How could this happen?

(2) Can it be fixed without destroying the cone?

1) A hard enough bump in transport can dislodge a magnet structure. Many magnet structures are placed using adhesives only, and those adhesives may loose integrity with age, doesn't take much for the magnet to stick to the pole piece, pinching the voice coil.
2) It is possible to re-align the magnet using a hydraulic jig, then re-glue in place, but very difficult (as in nearly impossible...) as the tolerances are very tight. Since the pinch may have damaged the voice coil, even if you could re-align the magnet, the speaker still might not be worth saving.

If you have more of the same type of driver, re-gluing the exterior with JB Weld or similar epoxy may save the speaker from future destruction.

 

[Disco-Pete]

You can do it in a jig using shims like in a door jamb install. Just fix the basket in place first.

 

[Disco-Pete]

I have a subwoofer where the magnet is no longer square to the cradle. Obviously the voice coil rubs against it when the unit is driven.


(1) How could this happen?

(2) Can it be fixed without destroying the cone?

I've no idea how to upload an attachment on this site otherwise I'd post a pic.

How did you come to notice it?

 

[weltersys]

Just fix the basket in place first.

How do you "just fix the basket in place" ?

 

[Surtsey]

How did you come to notice it?

I heard it.

 

[Disco-Pete]

How do you "just fix the basket in place" ?

In a jig. You have to hold it in place on a board using supplied holes. Then construct a simple framework to support the magnet against the shims.

 

[Disco-Pete]

I heard it.

Had you been using it when it happened or immediately on installation? I'm asking because it's possible it came loose from heat from abuse

 

[Surtsey]

No. I believe it was a transit issue. I will attempt to fix it using a vice and some Superglue.

 

[Disco-Pete]

No. I believe it was a transit issue. I will attempt to fix it using a vice and some Superglue.

Make sure it's in a gel form