+ Reply to Thread
Page 1 of 3 123 LastLast
Results 1 to 10 of 26

Thread: Kit to re-magnetise speaker drivers

  1. #1
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 856
    I'm Chris.

    Default Kit to re-magnetise speaker drivers

    Has anyone in the UK come across the sale of kit to (re)magnetise drive units.
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB I Signature
    SW1X DAC III Special
    SW1X Open Baffle Speakers containing both vintage and modern alnico drivers and paper cones. All silver wired and crossover-less where possible - 4" vintage Siemens Klangfilm tweeters, 8" SEAS exotic W8 midrange drivers and vintage 15" Altec VOTT 416 bass drivers
    DRD 45 single ended, 45 triode, monoblocks,
    Silver mains cables, interconnects and speaker cables by SW1X

  2. #2
    Join Date: Jan 2009

    Location: Essex

    Posts: 21,420
    I'm openingabottleofwine.

    Default

    First of all you would need to remove the magnet from the speaker basket and cone/voice coil assembly, which will be difficult.

    Second the gap flux (the strength of the magnetic field in the voice coil gap) is very large. Magnets are made by placing a magnetisable material into a large coil of wire and passing a heavy direct current through the coil. This requires specialist equipment, normally only possessed by magnet manufacturers, though some speaker manufacturers may have the necessary equipment.

    The only manufacturer of magnets in the UK that I know of is Eclipse, https://www.eclipsemagnetics-shop.com/ , though at work we used rare-earth magnets made by a German company called Vacuumschmelze. https://vacuumschmelze.com/

    Probably the best bet is to contact a speaker manufacturer to see if they could do the work, or if they don't do it themselves, to send your magnets away to be re-magnetised.
    Barry

  3. #3
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 856
    I'm Chris.

    Default

    Quote Originally Posted by Barry View Post
    First of all you would need to remove the magnet from the speaker basket and cone/voice coil assembly, which will be difficult.

    Second the gap flux (the strength of the magnetic field in the voice coil gap) is very large. Magnets are made by placing a magnetisable material into a large coil of wire and passing a heavy direct current through the coil. This requires specialist equipment, normally only possessed by magnet manufacturers, though some speaker manufacturers may have the necessary equipment.

    The only manufacturer of magnets in the UK that I know of is Eclipse, https://www.eclipsemagnetics-shop.com/ , though at work we used rare-earth magnets made by a German company called Vacuumschmelze. https://vacuumschmelze.com/

    Probably the best bet is to contact a speaker manufacturer to see if they could do the work, or if they don't do it themselves, to send your magnets away to be re-magnetised.
    Thanks Barry. I have found it very difficult to find someone that will do it, so for that reason I thought of buying the kit and offering the service myself. From my enquiries it seems that if your magnetising coil chamber is big enough then you can place the whole driver in there without having to dismantle it. In reality it only needs to be deep enough to accommodate the driver magnet. The basket etc can stick out the top.

    Do I have this right.
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB I Signature
    SW1X DAC III Special
    SW1X Open Baffle Speakers containing both vintage and modern alnico drivers and paper cones. All silver wired and crossover-less where possible - 4" vintage Siemens Klangfilm tweeters, 8" SEAS exotic W8 midrange drivers and vintage 15" Altec VOTT 416 bass drivers
    DRD 45 single ended, 45 triode, monoblocks,
    Silver mains cables, interconnects and speaker cables by SW1X

  4. #4
    Join Date: Jan 2009

    Location: Essex

    Posts: 21,420
    I'm openingabottleofwine.

    Default

    I'm not sure.

    I would have thought the original magnet was made by magnetising the outer part first (the part external to the speaker), then the magnet is assembled with the centre coaxial pole piece to create the strong gap flux experienced by the voice coil.

    If you re-magnetise by placing the whole magnet assembly into the magnetising coil, you will end up with a magnet having one pole at the speaker cone end (including the centre pole piece) and the other pole at the back of the magnet. There will be no (or very little) field in the voice coil gap.
    Barry

  5. #5
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 856
    I'm Chris.

    Default

    Quote Originally Posted by Barry View Post
    I'm not sure.

    I would have thought the original magnet was made by magnetising the outer part first (the part external to the speaker), then the magnet is assembled with the centre coaxial pole piece to create the strong gap flux experienced by the voice coil.

    If you re-magnetise by placing the whole magnet assembly into the magnetising coil, you will end up with a magnet having one pole at the speaker cone end (including the centre pole piece) and the other pole at the back of the magnet. There will be no (or very little) field in the voice coil gap.
    Thanks Barry. That seems a fundamental issue. I will do some googling.
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB I Signature
    SW1X DAC III Special
    SW1X Open Baffle Speakers containing both vintage and modern alnico drivers and paper cones. All silver wired and crossover-less where possible - 4" vintage Siemens Klangfilm tweeters, 8" SEAS exotic W8 midrange drivers and vintage 15" Altec VOTT 416 bass drivers
    DRD 45 single ended, 45 triode, monoblocks,
    Silver mains cables, interconnects and speaker cables by SW1X

  6. #6
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 856
    I'm Chris.

    Default

    Found this so far.

    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB I Signature
    SW1X DAC III Special
    SW1X Open Baffle Speakers containing both vintage and modern alnico drivers and paper cones. All silver wired and crossover-less where possible - 4" vintage Siemens Klangfilm tweeters, 8" SEAS exotic W8 midrange drivers and vintage 15" Altec VOTT 416 bass drivers
    DRD 45 single ended, 45 triode, monoblocks,
    Silver mains cables, interconnects and speaker cables by SW1X

  7. #7
    Join Date: Jan 2009

    Location: Essex

    Posts: 21,420
    I'm openingabottleofwine.

    Default

    Have no idea of the size of the coil windings (or the number of turns), but judging by the size of the current carrying cables feeding it and the size of the power supply, a pretty heavy current is used. I couldn't see if the amount of current was indicated on the power supply.
    Barry

  8. #8
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 856
    I'm Chris.

    Default

    Quote Originally Posted by Barry View Post
    Have no idea of the size of the coil windings (or the number of turns), but judging by the size of the current carrying cables feeding it and the size of the power supply, a pretty heavy current is used. I couldn't see if the amount of current was indicated on the power supply.
    I have seen other magnetisers working on smaller drivers and I believe they charged the magnet at 600v. I am not looking to build the kit, just buy it
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB I Signature
    SW1X DAC III Special
    SW1X Open Baffle Speakers containing both vintage and modern alnico drivers and paper cones. All silver wired and crossover-less where possible - 4" vintage Siemens Klangfilm tweeters, 8" SEAS exotic W8 midrange drivers and vintage 15" Altec VOTT 416 bass drivers
    DRD 45 single ended, 45 triode, monoblocks,
    Silver mains cables, interconnects and speaker cables by SW1X

  9. #9
    Join Date: Mar 2017

    Location: London N2

    Posts: 1,741
    I'm Edward.

    Default

    Chris, interesting idea of re-magnetising speakers. Not really come across this much before so did a bit of googling.

    Interesting article about how speaker magnets lose their quality etc here.

    Do you have any research which shows improvement that can be had after re-magnetising? Are you thinking of providing a service?

    A related subject are speakers with field coils (eletromagnets). I purchased an item from a guy who had a pair of Wolf von Langa field coil speakers. Unfortunately it was not possible at that time to have a listen but from what I read the sq has a naturalness not generally found in 'normal' speakers.
    Main: Tidal/Roon > MiniITX > Metrum Hex > LDR > either Radford STA25 V or Trilogy 968 > Tannoy (Eaton or Berkeley).
    2nd: Tidal/Roon > Roopio on Pi > Chevron Paradox > Firebottle Buffer > Sugden Masterclass IA-4 > Kudos Cardea


  10. #10
    Join Date: Jan 2009

    Location: Sheffield - UK

    Posts: 6,715
    I'm Mark.

    Default

    Is it Alnico magnets you are thinking of (if not I wouldn’t bother). As for magnetising, I’ve seen two videos from manufacturers (ATC and Harbeth as I recall) and both showed the magnets being magnetised once the whole speaker (the drive unit that is) had been built.

    100% Analogue

+ Reply to Thread
Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •