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Long vs Short pokepieces

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  • #16
    Re: Long vs Short pokepieces

    Originally posted by freefrog View Post
    Yep: see for example Wade Westbrook from Motor City Pickups (@ Detroit; one of the finest artisans in USA from my European POV). :-)

    And FWIW, tuning already existing pickups can save money by avoiding an expensive swap. I'm periodically upgrading pre-existing PU's by manipulating their magnetic and LRC specs for this reason.





    A same set of HB’s has been tried here in a semi hollow, a Flying V then a double neck guitar with bolt on necks.
    Same scale, same pots, same strings, similar hardware.
    In the last guitar, on both pickups, the screw poles below the G string had to be elevated of several mm (!).

    In my understanding, such differences are due mostly to a “comb filtering” effect caused by the physical structure of the guitars and their vibrational modes.

    Now, it doesn't deny the role of screw poles and their complex interaction with other parts of the pickups. Even plated vs non plated pole pieces can make a (slight but noticeable) difference IME. :-)
    Thanks, good input

    Just an hour ago, I pulled a long polished A2 magnet from a humbucker and replaced it with a short, rough A5. Besides the fact that this humbucker now sounds awesome (which was the sole purpose of the operation) I'm surprised it doesn't require nearly as much staggering as before...
    Same guitar, same coils, same pickup height (meaning about the same output), same everything including the pole screws. The only difference is the magnet. Go figure.

    Sure the pickup now has a different frequency response, but remember that each pole screw, each string covers up to 2 octaves, hereby overlapping the adjacent strings. So pole screw adjustment is first and foremost about compensating the difference in magnetic pull.

    (I don't mind adjusting pole screws, that's the reason they exist...in most buckers..., I just like to better understand why some pickups behave the way they do and what can be done to tune them when required.)

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    • #17
      Re: Long vs Short pokepieces

      Originally posted by Al Nico V View Post
      Just an hour ago, I pulled a long polished A2 magnet from a humbucker and replaced it with a short, rough A5. Besides the fact that this humbucker now sounds awesome (which was the sole purpose of the operation) I'm surprised it doesn't require nearly as much staggering as before...
      Same guitar, same coils, same pickup height (meaning about the same output), same everything including the pole screws. The only difference is the magnet. Go figure.
      An A5 diminishes the inductance compared to an A2 and even more so if it's a short one. But it's magnetically stronger. These parameters suffice to explain your experience in my humble understanding. :-)

      Now, there was long RC A5 bars in the set mentioned in my previous post... but it still needed some serious pole staggering in the last guitar fitted with it.

      Regarding screw poles in general: for the record and ironically, Seth Lover hadn't included this feature in his first HB design (!)... :-)) But he did know what kind of effect it has, of course. :-)

      In June 1978, Seymour W. Duncan visited Seth E. Lover - inventor of the Gibson ‘Patent Applied For’ humbucking pickups - at his home in Garden Grove, California. Here is that discussion for your reading pleasure.


      ... and a post scriptum regarding magnets, generally speaking: when I test bar mags with our teslameter, I'm often fascinated by how uneven is their magnetism. Some bars are stronger in the middle, others are strong at both ends with a weaker zone in between, others are strong on one side only, and so on... Granted, these strong and weak spots fade in one common field but IMHO & IME, uneven magnetism is one more random parm to take in account here (not to mention the somehow counter-intuitive shape of a typical mag field, as illustrated by the pic named "screw poles for a humbucker" here: http://www.skguitar.com/SKGS/sk/Imag.../Magnetics.htm ).
      Last edited by freefrog; 02-26-2020, 09:10 AM.
      Duncan user since the 80's...

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      • #18
        Re: Long vs Short pokepieces

        Originally posted by freefrog View Post
        An A5 diminishes the inductance compared to an A2 and even more so if it's a short one. But it's magnetically stronger. These parameters suffice to explain your experience in my humble understanding. :-)

        Now, there was long RC A5 bars in the set mentioned in my previous post... but it still needed some serious pole staggering in the last guitar fitted with it.

        Regarding screw poles in general: for the record and ironically, Seth Lover hadn't included this feature in his first HB design (!)... :-)) But he did know what kind of effect it has, of course. :-)

        https://www.seymourduncan.com/blog/t...ith-seth-lover
        Yeah I've heard that before. Seth Lover would have used a wound G, that's the only way he could get away without pole compensating an A2 magnet like the one i took out...his pickups probably were lower wind...Anyway, they were smart enough to launch the PAF with pole screws. Clever move.

        Here's the tall tale coming from the man:

        "I wanted them to sell it without any adjusting screws because I found that with this there was much difference between the first and second strings like there is on most of the old non adjustable type there was quite a difference in the first and second string but this didn’t seem to have that major difference, and I thought it was not necessary to have pole pieces… well when you take away a talking point from a salesman it’s like breaking off your arm… The first thing I came up with an idea was just fake some things there so I stamped them on the cover, that didn’t please them either, by that time we already made the patent application… that’s why it went through that way, so they finally decided they wanted screws in there, so I put adjusting screws in it for them, then the question they asked me then was which way should those screws set? Should they set up or down? Well you’ve got to give them an answer so I decided to take the one closest to the fingerboard and put the screws facing it and the one closest to the bridge towards the bridge! [Laugh] that made them happy, they had a set way that it should be set, it only amounted to turning the pickup around…" (Seth Lover)

        I call baloney . I believe some of those "salesmen" were actually guitar players.


        Originally posted by freefrog View Post
        ... and a post scriptum regarding magnets, generally speaking: when I test bar mags with our teslameter, I'm often fascinated by how uneven is their magnetism. Some bars are stronger in the middle, others are strong at both ends with a weaker zone in between, others are strong on one side only, and so on... Granted, these strong and weak spots fade in one common field but IMHO & IME, uneven magnetism is one more random parm to take in account here (not to mention the somehow counter-intuitive shape of a typical mag field, as illustrated by the pic named "screw poles for a humbucker" here: http://www.skguitar.com/SKGS/sk/Imag.../Magnetics.htm ).
        Yes, yes, I think this is the answer. Good info.

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