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Metal pickguards and inductance

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  • Metal pickguards and inductance

    Hey all,

    I just managed to find a Fender chrome on brass pickguard. It looks fantastic, but there is a top end roll off, plus the voice of the pickups changed a bit. Doing a little reading I’ve read others suggest that non-magnetic but conducive pickguard alter the inductance of pickups. With that in mind, would applying coats of clear over the guard (making it non-conducive eliminate this effect? The Chrome guard is just too cool looking to give up on.

    I know, odd question. Figuring a pickup forum is a good place to ask though

  • #2
    Re: Metal pickguards and inductance

    If you notice top end roll off and an alteration of the inductance, it's due to Foucault currents/ eddy currents.

    If there's eddy currents, the problem is magnetic. Putting clear coats on the pickguard won't change anything, exactly like putting adhesive tape on a mag woudln't change its magnetism.

    If eddy currents bother you, you could rise the resistance of your pot(s) and/or use some no load tone pot(s). It would bring back the dampened high frequencies.

    FOOTNOTE - In the early 80's, I had a Strat copy with SSL1's in... a brass pickguard. It didn't harm the brightness because I had made the tone pot switchable. Not that I was understanding Foucault currents 4 decades ago but intuition or luck had helped me to take what I decipher nowadays as the right decision.

    FWIW (my 2 cents). Good luck in your tone quest. :-)
    Duncan user since the 80's...

    Comment


    • #3
      Re: Metal pickguards and inductance

      Originally posted by freefrog View Post
      If you notice top end roll off and an alteration of the inductance, it's due to Foucault currents/ eddy currents.

      If there's eddy currents, the problem is magnetic. Putting clear coats on the pickguard won't change anything, exactly like putting adhesive tape on a mag woudln't change its magnetism.

      If eddy currents bother you, you could rise the resistance of your pot(s) and/or use some no load tone pot(s). It would bring back the dampened high frequencies.

      FOOTNOTE - In the early 80's, I had a Strat copy with SSL1's in... a brass pickguard. It didn't harm the brightness because I had made the tone pot switchable. Not that I was understanding Foucault currents 4 decades ago but intuition or luck had helped me to take what I decipher nowadays as the right decision.

      FWIW (my 2 cents). Good luck in your tone quest. :-)
      Thanks! Great observation. I’m using the psychedelic set with 250K pots. I’ll swap out the volume for a 500K and see where that takes me. That’s easier than painting and the rest for sure.

      Thanks again

      Comment


      • #4
        Re: Metal pickguards and inductance

        Eddy currents occur in a conductor in the presence of a magnetic field. The currents produce their own magnetic field which opposes the magnets in the pickups. This causes the high frequency loss.


        Sent from my iPhone using Tapatalk

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        • #5
          Re: Metal pickguards and inductance

          Originally posted by DavidRavenMoon View Post
          Eddy currents occur in a conductor in the presence of a magnetic field. The currents produce their own magnetic field which opposes the magnets in the pickups. This causes the high frequency loss.
          Glad to know that you seem to get well in these complicated times, David - and thx once again for sharing generously your knowledge of winder for decades, here and on other forums.

          Originally posted by RockinProf View Post
          Thanks! Great observation. I’m using the psychedelic set with 250K pots. I’ll swap out the volume for a 500K and see where that takes me. That’s easier than painting and the rest for sure.

          Thanks again
          You're welcome. May I suggest you to swap the tone pot instead? Reasons: it would be even easier (if the "ground bus" is soldered on the housing of your volume), you could change it again for a no load model if necessary AND your original 250k volume might seem preferable when you lower it - since a 500k pot @6/10 puts more resistance between the pickup and output, changing the taper of the control.

          Good luck again. :-)
          Duncan user since the 80's...

          Comment

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