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subway train affecting pickups?

Discussion in 'Pickups & Electronics [BG]' started by brooklynbassguy, Oct 19, 2005.


  1. brooklynbassguy

    brooklynbassguy Supporting Member

    Feb 8, 2004
    maplewood, nj, usa
    Years ago, when I first moved to nyc. A famous, nerdy bassist told me that the magnets on subway motors can hasten the demagnetizing of bass pickups. Any truth in this?
     
  2. fookgub

    fookgub

    Jun 5, 2005
    Houston, TX
    Doubt it. You would have to be very close to the magnets, and they would have to be aligned properly to demagnetize the pickup. Also, this would only work with Alnico... neodymium magnets are very difficult to demagnetize with an opposing field.
     
  3. brooklynbassguy

    brooklynbassguy Supporting Member

    Feb 8, 2004
    maplewood, nj, usa
    I did say years ago, almost 20, when alnico was the norm...
     
  4. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    If it would demagnetize pup magnets, why would it not demagnetize anything else? All telephones rely on magnets to operate. Speakers use them as well as the coupling force in automotive speedometers etc..

    My guess is that it would be completely impossible for that to be true.
     
  5. brooklynbassguy

    brooklynbassguy Supporting Member

    Feb 8, 2004
    maplewood, nj, usa
    How many telephones or automobile speedometers have you seen on the nyc subway system? I'm talking about if you're a regular subway rider, and you have your gigbag resting on the floor, which is right above the motors.
     

  6. carry a compass...if it points towards the floor...you've got a problem...

    otherwise....**in my best NY accent** FORGET ABOUT IT!
     
  7. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    It won't hurt your pickups and may improve the upper midrange response of your cables.

    If you really want to protect your bass from magnets don't let it get near your amp or speakers ;)
     
  8. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    OK, your friend is absolutely right. If that's what you want to believe.
     
  9. fookgub

    fookgub

    Jun 5, 2005
    Houston, TX
    Try alternating your bass on each ride. Leave it face down on the way out to the gig to "over magnetize" your pickups for a fat, cutting sound. Then leave it face up on the way home to demagnetize the pickups back to the way they were. ;)
     
  10. brooklynbassguy

    brooklynbassguy Supporting Member

    Feb 8, 2004
    maplewood, nj, usa
    Sorry, I thought this was a serious forum!
     
  11. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    Did you think I was kidding about keeping your bass away from speakers?
     
  12. First of all, they're frequently upgrading the trains all the time. You would not only need an expert in the subway cars of today but also an expert of cars in the time period you're suggesting. It's possible that back then, in the worst case scenario, the powerful electric motors could somehow weaken the magnets in your pickups but I rather doubt it.

    Now if this was something that truly "hastened" demagnetization, you would probably hear about it, right? I mean lots and lots of folks ride and have ridden the train every day with their electric guitars and basses and I've never heard of anyone noticing a change in their instrument. However, small changes can be hard to immediately detect and remember that the magnets already weaken slowly just from regular use.

    As far as the new trains go, who knows. Now with everyone being so cautious you can't really go around asking questions about how the car works and where the motors are, can you?! Haha. I wonder if any MTA or Bombardier employees are TBers?
     
  13. +1

    I remember this guy in college that thought it would be fun to see the inside of his cabinet. He took out the woofer and set it on his hardshell case, right on top of the pickups of course, and it took him about a day to figure out what had happened. :rolleyes:
     
  14. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    this thread's title has the makings for a blues song if ever there was one.

    From what I've gathered, it takes either an extremely powerful brief exposure to demagnetize mags or prolonged exposure of a somewhat lessor degree. Both being more or less direct contact. So my guess is, if it's not sucking everybody's handguns to the floor, it's not an issue.

    What you don't want to do with alnico's is expose them to excessive heat by grinding or forcing like poles together. Ceramics and Neo's are fairly impervious.
     
  15. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    I remember a science experiment as a kid where you could rub a nail on a magnet and it would magnetize the nail. So I won't let kids rub nails on my bass.
     
  16. jgsbass

    jgsbass

    May 28, 2003
    Floral Park, NY
    Having used the subway's within the aforementioned time frame, I assure you that nothing ever happened to my pickups. Or to the hundreds of other string friends, both bass and guitar, from having a demagnetizing moment. The strip on everyones credit card would probably be the first victim as it has magnetically coded info.
     
  17. brooklynbassguy

    brooklynbassguy Supporting Member

    Feb 8, 2004
    maplewood, nj, usa
    I have said this was described as a gradual effect from repeated exposure-regular subway riding. Ever hear of anybody getting their pickups remagnetized?
     
  18. pkr2

    pkr2

    Apr 28, 2000
    coastal N.C.
    It actually takes a rapidly collapsing magnetic field to degaus (demagnetize) a magnet. Your monitor (if it uses a crt) has a degausing coil around the screen very close to the shadow mask inside the crt. Each time the monitor is turned on tne coil of wire has an AC voltage applied through it, very effectively demagnetising the shadow mask. It takes several amps of current to remove the VERY weak residual magnetism in a shadow mask. It is more likely to enforce the magnetism of a magnet by exposing it to a permanent magnetic field than it is to remove the residual magnetism.

    The magnetic field that is created around a MRI machine in a hospital is dangerously strong but it creates no problem with the multitude of magnets used in the machine itself.

    IT would take an extremely long time to demagnetize one magnet with another permanent magnet, if it ever did. Forcing opposing fields together could never do more than equalize the strength of the two magnets.

    If there was any risk from the magnetic fieild around the motors in a subway application, the motors would definitely be shielded with mu metal which very simply and effectively blocks a magnetic field.

    I don't mean to come sounding like I know everything there is to know about magnets but everything I've said is very basic electrical theory.

    :) :)
     
  19. luknfur

    luknfur

    Jan 14, 2004
    DIXIE
    FWIW:

    Magnets can be remagnetized - apparently fairly cheaply when paying to have it done - with controlled exposure to an intense magnetic field (which apparently is the way it's done) or by current flow - as in the nail/friction/electrostatic example. The process polarizes the charge so there's a dominant orientation of the natural north/south charges within the material.

    A magnet's intensity is measured in gauss while oerstads is the materials capacity to resist demagnetizaton (reluctance). The ALuminum/NIckel/CObalt combination is popular because it's properties are conduscive to magnetism but has poor reluctance. That is why you don't want to force like alnico poles together. Opposing poles naturally attract and require force to pull them apart while like poles repell and require force to push them (and keep them) together. I was astounded by how much force it takes to pull two MM alnico 5 pups apart that had inadvertantly sucked together when they got in close proximity.

    On the surface it would seem a good way to store pups would be to have them "suck face" as it it would seem to strengthen or at least maintain polarity. Sometimes poles are staggered in a way that the a pair could not be aligned with all poles oppposite. That's usually pretty apparent becuase they will suck up but twist to one side or the other when placed face to face and allowed to attract. When they suck tight in alignment, all poles should be opposite. That is not how manufacturers ship their pups however and I've never seen such practice recommended.
     
  20. Moo

    Moo Banned

    Dec 14, 2002
    Oakland, CA
    Ever hear of healing magnets?

    http://www.health-magnets.com/

    You asked a question but seem to be upset with people not giving you the answer you want to hear.