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Good vs bad pickup cover: an example of what it can do.

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  • Good vs bad pickup cover: an example of what it can do.

    Quick testimonial about two chrome covers meant to be made of correct materials and visually identical. The "bad" one is not even thicker. But it brings a considerable amount of eddy currents and trims the high range accordingly.

    Result: changing the cover made much more difference than changing the magnet. :-P

    Pic below. Electrically induced response in the upper part of the screen. Other lines under it show the phase response (dotted curves) and THD. The pickup was a boutique P.A.F. clone.

    One can see how ceramic vs UOA5 magnets under the bad cover make a hardly noticeable difference in the measured response, albeit the inductance was clearly affected (falling of 0.2 to 0.4H with the ceramic bar). The bad cover, conversely, shifts up the resonant peak and lowers it of 5dB...

    Note - The pickup ended uncovered. It's an unpotted model and there was no way to avoid it to squeal with gain whatever was the cover tried.

    FWIW. Might be useful for some players, who knows? ;-)

    Click image for larger version

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    Duncan user since the 80's...

  • #2
    VERY interesting.
    Again, thanks for sharing your knowledge and experience with relevant topics. I knew that a metal cover makes a difference, but I would have never guessed that it would make this much difference especially relative to a magnet change.

    At this point it might be good to define "good" cover and "bad" cover.
    Originally Posted by IanBallard
    Rule of thumb... the more pot you have, the better your tone.

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    • #3
      Originally posted by GuitarDoc View Post
      VERY interesting.
      Again, thanks for sharing your knowledge and experience with relevant topics. I knew that a metal cover makes a difference, but I would have never guessed that it would make this much difference especially relative to a magnet change.

      At this point it might be good to define "good" cover and "bad" cover.
      Hey, I was replying to your topic while you were answering to mine... Thx for the kind words. :-)

      I'd like to be able to define and recognize good and bad covers in a simple way ... Both of those used above came without label from a part bin and I've been forced to do electrical tests to check if they were magnetically transparent. What this test revealed is explained above...
      I can certify that Gibson chrome covers are "good" as are most of the parts sold by well-known brands. But I've already got non transparent covers from reputable sellers and even found a couple of "bad" covers above "good" pickups.

      To know if a cover is good or not (IOW: magnetically transparent), it would be necessary to sand them in order to see how many layers are under the finish and which materials they involve. "Bad" covers typically include an excessive amount of materials causing eddy currents (like copper / brass)...
      Duncan user since the 80's...

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      • #4
        freefrog is a gift to this forum.

        Sounds like:

        1) Going uncovered eliminates another variable if you want to simplify things.
        2) If you're going covered, go with a good brand.
        3) If you're uncovered and you want to cover it yourself, it's best to get a good quality cover from a well known brand instead of the cheap ones you see online.

        I rarely use covers unless it suits the aesthetic of the guitar. I have one with covered pickups, both chrome/nickel and Gibson (57+ and 498t), and I have one with a covered chrome/nickel SD in the neck and an uncovered bridge pickup (A2PB and Custom 5).

        I seem to like a covered A2 in the neck for a more vintage sound (A2PB), but covers do seem to make things sound a little more nasally to my ears. In the bridge I left the other pickup uncovered because it was supposed to be fairly open, aggressive, and thumpy anyway (Custom 5). It was also the only one I had. Pretty sure it's a trem spaced Custom 5 that I put in an EC256.

        I thought the LTD's bridge spacing might have been slightly wider than Gibson's to avoid litigation, but a regular spaced humbucker looks better in the bridge. I haven't noticed any tonal issues like notes dying out on bends. It's mostly just looks--the trem spaced C5 looks too wide for the EC256 bridge. The mismatch kind of works in this case since covered/uncovered gives it a bit of a pawnshop/partscaster look.

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