DC Resistance or Millivolt (mV)

Discussion in 'Pickups' started by scozz, Oct 4, 2017.

  1. scozz

    scozz Senior Member

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    I've noticed a lot of folks measure a pickups DC Resistance and equate that with the output of the pickup. From what I've read DC Resistance is only one of many things to consider when determining the output of a pickup. And that using the millivolt reading, (mV) is a much more accurate way of measuring the output.

    For example...a Dimarzio Super Distortion, (listed as a HIGH output PU) has a DC Resistance of 13.68k and a mV of 425...

    ...while a Dimarzio AT-1, (listed as a MEDIUM output PU) has a DC Resistance of 16.50k and a mV of 320.

    What's the consensus here?
     
  2. DarrellV

    DarrellV Likes > Posts Silver Supporter Premium Member

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    Hey scozzy! :cheers:

    The winders in here will all tell you that DCR is a waste of time at best, and only used by MFRS because consumers demanded something they could use for buzz words.

    DCR changes with the length of wire, true, more wire, more resistance.... but also with gauge, or wire thickness.

    Thicker wire used for an equal length will still give lower resistance.

    Less of thinner wire and more of thicker wire also equal in resistance. So it's futile.

    Add to that you amp does not see resistance. Resistance impedes current, it doesn't actuate anything of itself. So it cannot drive the front end of your amp.

    mVolts, now THAT is a motive force that can and does drive the front end of your amp.

    Voltage, or Electromotive Force is the invisible stuff that pushes electrons down the wire.

    More voltage, more push, more current flow. it's the same at the mV level as it is in the kV level.

    So in a pickup, more mV = more push, what we call 'hotter' hitting the preamp with more force. Less amp gain is needed to reach breakup.

    Less mV = lower output usually cleaner and takes more to get it to break up.

    Makes sense because the pickup is hitting the front end with less juice, so we crank the pre amp knob for more boost.
     
  3. Antigua

    Antigua Senior Member

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    The DC R just suggests how many winds of wire are on the coil(s), but you have to know, or be able to guess the gauge of the wire in order to make much sense of it. The only truly useful value is the inductance, because the actual output voltage is dependent upon the impedance of the coil(s). The other factor, which is harder to quantify, is how much flux change can be seen by the pickup as the strings move around, as pickups operate based on Faraday's Law. This is why ceramic produces more output, because the ceramic magnetically charges the strings more strongly when the strings come closer to the pickup, so there is greater flux change, hence a higher voltage output. So there is potential that change when you swap out the magnets, and other parts, that is hard, or maybe impossible, to express as a single number. You'd need something like an internationally agreed upon standard, then you can say, under conditions X, the pickups produces output Y, and then that value could be meaningfully exchanged.

    The thing about DiMarzio's mV output is that we have no idea what methods they use to gather that data, and we have no ability to be certain that they use precisely the same method for every pickups tested. If they were just making these numbers up, we'd have no way to prove or disprove it. They have no incentive to be precise or consistent, considering they can't be held to account. If ever you disagreed with their values, they could just claim you didn't set the pickups to the correct height, or used guitar strings that were too thick or too thin, etc.
     
    Last edited: Oct 4, 2017
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  4. ARandall

    ARandall Senior Member

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    And then if you were to get a certain consensus on output, that might change with the amp and speaker used.....as amps are not linear or flat in their boost, and neither are speakers.
     
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  5. scozz

    scozz Senior Member

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    Thanks Darrell! :thumb: Great info!

    BTW...did you see this thread...

    Hey Darrell...Check this Out!
     
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  6. darthphineas

    darthphineas Senior Member

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    mV. always Mv.

    except that there's no 'industry standard', so that if all companies used the mV system, it wouldn't translate from one company to another. however, it should be a good scale among the products of a specific company that does offer output rating in mV.

    going with DCR is a fallacy that's gone on way too long and it should be an embarrassment that one of the big companies fed in to that for as long as they did (and sorta still do).

    for a quick example of how DCR does NOT equal output go to the DiMarzio site and look up the DCR and mV specs on the Super D, the Super 2 and the Super 3.
     
  7. scozz

    scozz Senior Member

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    Right.

    That's what I was referring to....

    ...a Super 2 has a DCR of 8.7k and a mV of 400 (high output)...

    ...a Super 3 has a DCR of 25.00k and a mV of 435 (high output)

    ...a PAF 59 has a DCR of 8.5k and a mV of 215 (vintage output)...
     
  8. darthphineas

    darthphineas Senior Member

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    :thumb:


    ...a Super 2 has a DCR of 8.7k and a mV of 400 (high output)...
    ...a Super 3 has a DCR of 25.00k and a mV of 435 (high output)

    a Super D has DCR of 13.68 and a mV of 425

    all output in the similar mV range with DCR ranging from 8.7 (what some would call vintage) to 13.68 (what some would consider medium-hot) to 25.00 (what everyone would consider scorching).

    some players don't care for DiMarzio for all sorts of reasons, but they deserve a bit of credit for doing their part to dispel the "DCR = output" myth



    still, it's all moot if there's not a common method that all pickup companies use to measure mV. it'd be cool if it happened, but there's little realism in the hope that it might. ;)
     
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  9. ehb

    ehb Chief Discombobulator Premium Member

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    What Darth said... :)



    DCR just gives a general 'idea' about the coil itself. It does not take into account the magnet which can make a helluva lot of difference in how that pickup sounds in a guitar... There are sites out there where the pickup guru changes mags in the same pickup and records the difference... It can be VERY surprising....

    Measuring R is simply the R of a length of wire using DC voltage and measuring the resultant current on some scale representing voltage. It is DC voltage, so all the neato whizbang inductor Θ magic does not apply after a very very very short time at the instant DC is introduced to the circuit. After that time, the coil is not in the circuit electrically speaking, just a long wire.... It can give you a general idea of magnitude of turns kinda sorta... You could also have a shit solder connection and/or bad hookup wire and all that is out the window... Fixed many bad solder joints over the years that janked the output of a perfectly good pickup... Some folks should never be left alone in the same room as a soldering iron... :cool:

    Also for future reference and a laugh at a good dumbass moment, a close bud that knew damn better, nuked a perfectly good badass vintage single coil bridge pickup playing with a freaking moly magnet... I recharged it for him and told him next time I'd choke him down for being stupid... Coil would have measured fine.... You should have heard that guitar though.. Weirdest damn sound I've heard...

    Never hold a magnet in your hand around a guitar. You will get to wondering "what if", dick up a pickup, and I'll want to choke you...
     
  10. cooljuk

    cooljuk Transducer Producer Premium Member MLP Vendor

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    Darth pretty much nailed it.

    Milivolts are meaningless unless you have all pickups in a similar test bed. How hard you hit the strings, much less what type of strings, how far they are form the pickup, how far the pickup is form the end of the strings, what the scale length is, etc. will all screw up mV measurements so you have to have a test jig to induce an identical signal mechanically into the pickup (induction signal would not work, as it doesn't take the magnet into consideration, which is a huge part of pickup output) from an exact distance and angle away.

    Here's an article I wrote given great detail and specific examples to why DCR is not only minimally informative about it pickup but can actually be outright misleading. http://www.mylespaul.com/threads/th...-resistance-in-regard-to-pickup-coils.369099/


    What Antigua misses, is that two coils can be wound with the exact same spool of wire, onto the exact same bobbin, with the exact same tension, and even with the exact same turn counts, and STILL result in different DCR figures. An experienced coil winder from any background will know why, as it's quite simple.
     
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  11. ehb

    ehb Chief Discombobulator Premium Member

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    Quoting cooljuk's referenced page with great info and NOT to steal his fire in any way, rather to repeat things commonly overlooked by the regular popcorn munchers:

    <quotimoto>
    This is scraping the tip of the iceberg. Steel alloys, mass and shape of pole pieces, coil patterns and shape, turns per layer, wire tension, wire type, insulation thickness, charge level of magnets, magnets of the same type and charge from different foundries and lots - all of these are just some examples of variables that significantly alter the sound of a guitar pickup
    <nomoquotimoto>

    The magnetic properties of the entire system can have much more effect on how a pickup sounds than mere number of turns.... "Turns" is just one component in the system.... There is a lot going on in a pickup/string system....

    Even string alloys can jank with a pickup's tone...

    Guy came in my shop a few months back with a bass acting real weird on one string's output...other strings inconsistent at best.... Damn chinese bulk bass strings... Put a set of NYXL strings on it and it immediately went from puke factor to righteous... I told him there was a reason the chinese bulk strings were under four bucks a set... He came in thinking he was gonna have to buy new pickups... Left as a happy camper for the cost of a good set of bass strings....


    Great info, cooljuk, and spelled out nicely!

    edro.
     
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