Pickup Volume: magnets, # of winds, gauge

Discussion in 'Just Pickups' started by youdevil, Jan 5, 2013.

  1. youdevil

    youdevil TDPRI Member

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    I'm experimenting with some new p90 pickup building approaches and wonder what the relationship is between strength of magnet, number of windings and wire gauge.

    Example: using 43 gauge wire, I wrap the bobbin x-number of times and get a reading of 8.5k. But until I drop the magnet in, the volume of that pickup is very low because the wire itself generates very little flux.

    Yet, when I DO drop the magnet in, even though the pickup is much louder the output remains 8.5k.

    We are accustomed to equating output reading with "strength" yet obviously the mag field is critical, not just in terms of tone but perceived volume.

    Is output a useful measure only within a class of pickup? In other words, an output of 9.2k for, say, an alnico v humbucker only has comparative value to another alnico v humbucker, not with a p-90 or a tele single coil, etc?
     
  2. sjtalon

    sjtalon Doctor of Teleocity Ad Free Member

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    Resistance has nothing to do with output per se, and can not be called output.

    Your dc resistance readings are just the WIRE (more wire - more resistance, less wire less resistance). Nothing you do to that environment is gonna change that, like adding a magnet in the mix.

    Read up on electromagnetism.
     
  3. djalt

    djalt Tele-Holic

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    This needs to be a sticky and stay posted at the top of this forum permanently....
    :)
     
  4. Zexcoil

    Zexcoil Tele-Meister Vendor Member

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    Except that even that is an oversimplification.

    Resistance and output are related, just not 1 to 1.

    Given the same wire gauge and bobbin dimensions (neglecting things like winding technique - tension, layering pattern, and the decreasing strength of the field at each incrementally added winding), increased resistance does indicate more turns on the coil which means increased output - with the big caveat: all other things being equal.

    But they rarely are, right?

    DCR is an easy number to get, a great number to track and can tell you some meaningful things about a pickup, but:

    resistance does not equal output (at least without some serious qualifiers attached)

    and

    there are much more meaningful metrics to define pickup character.

    With respect to the OP, there are at least two very significant things happening when you put the magnet in the core, and they both can have a dramatic effect on output.

    1) the inductance of the pickup goes up dramatically, and
    2) the magnetic field strength goes up as well (from something near zero).
     
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