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Remagnetize old speakers

Discussion in 'General Electronics Chat' started by legac, Jun 5, 2005.

  1. legac

    Thread Starter Well-Known Member

    May 4, 2005
    Hi friends
    I would appreciate if you could tell me how to remagnetize an 12 inches old loudspeaker without detaching the magnet from its iron frame.
    Thank you
  2. pebe

    AAC Fanatic!

    Oct 11, 2004
    You cannot. You would need to remove the cone and voicecoil. Then strip the magnet and its polepieces from the frame. Then dismantle the polepieces to get the magnet on its own.

    It would then be possible to remagnetise it, but it's not a job for an amateur because specialised equipment is required.

    Assuming you could get that done, you would need to reassemble without the voicecoil 'scuffing' the polepieces in their anular gap. I would not try.

    Why do you think it needs remagnetising, anyway?
  3. legac

    Thread Starter Well-Known Member

    May 4, 2005
    Thank you for your promt reply. I have just bought a pair of old speakers- very old- It does not have any sign to identify the trademark. However It looks like the Bell&Howell speaker using for 16mm movie projector. Both moving coils are original, but one speaker sounds better than the other. I use a screw driver to check the magnetic and "feel" the stronger one sounds better.
    I think the loudspeaker producers do not magnetize the magnet before assembling. Perhaps they do the magnetising after assembling by using a very strong electric magnet?
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    The magnets are magnetized prior to assembly. One magnet geometry can be used for different speaker geometries while requiring only one set of fixtures for the magnet type. Otherwise, more fixtures would be needed.

    For remagnetizing, try forming your own coil and putting the speaker in (after checking poles with a compass). It probably won't work, but why not try? It does work for tiny speakers.