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Pickup Impedance

Discussion in 'Pickups & Electronics [BG]' started by EricssonB, Jan 2, 2013.


Pickup Impedance

  1. Most important thing ever; will ruin bass

    5 vote(s)
    10.2%
  2. Not a huge deal; will work fine

    12 vote(s)
    24.5%
  3. You're too hungry to think correctly; go make lunch.

    14 vote(s)
    28.6%
  4. tl;dr

    1 vote(s)
    2.0%
  5. dm;hs

    3 vote(s)
    6.1%
  6. ¯( ツ )/¯; all of the above.

    14 vote(s)
    28.6%
  1. EricssonB

    EricssonB Supporting Member

    Apr 5, 2011
    CoSpgs, CO.
    (search didn't yield what I was looking for)

    I hate to ask what feels like a "yeah, stupid" question, but I'm curious as how to be certain from reading tech specs of a pickup whether or not a P pickup (say, 10.4k) will match an MM-style pickup (8.4k).

    Folks say that the impedance itself isn't a huge factor once you consider placement, current produced, magnets, etc.

    Shoot me down, reply with a link or something. Thanks.

    This is why: http://www.talkbass.com/forum/f57/jag-build-ss-ss-942628/
    [​IMG]
     
  2. The impedance of a pickup means absolutely nothing on its own. For most pickups, the exact impedance is not even known. You simply know if it is higher or lower than that of another pickup, by using the DCR as a guide.

    On the other hand, impedance has a significant effect on the interaction between pickups when multiple pickups are blended, unbuffered. P and MM pickups tend not to blend well, because the MM loads the P.
     
    iiipopes likes this.
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  4. seang15

    seang15 Supporting Member

    Aug 28, 2008
    Cary NC
    Sorry, what is DCR? Thanks.
     
  5. DCR is DC resistance, which can be obtained with a multimeter. Impedance, on the other hand, includes both a resistance and a reactance. In the case of inductive or capacitive circuits, resistance is the real part which is not frequency dependent, and reactance is the complex part, which is frequency dependent.
     
  6. seang15

    seang15 Supporting Member

    Aug 28, 2008
    Cary NC
    Many thx!!
     
  7. EricssonB

    EricssonB Supporting Member

    Apr 5, 2011
    CoSpgs, CO.
    This is what I was getting at. Looking to have P and MM blended, so having similar impedance is probably for the best?

    Is there a tolerance for that +/-xx%?
     
  8. SGD Lutherie

    SGD Lutherie Banned

    Aug 21, 2008
    Bloomfield, NJ
    Disclosures:
    Owner, SGD Music Products
    Or to make it easier to understand, impedance can be thought of as AC resistance. As the frequency rises, so does the resistance.

    @EricssonB, so like L6M said, you aren't really talking impedance, but DC resistance. The higher resistance P pickup will tend to over power the lower MM, but they will work together, just not on equal footing. Kind of like with a P/J bass.

    If you want to have them blend with no interaction, you need to do so using a preamp with active blending.

    You should also reverse the P so they aren't so close to each other. It will sound more balanced that way.
     
  9. I'm sorry if I posted on an old thread, but I was intend to do the exact things about P+MM, I will use an active preamp (ACG)
    by using an active preamp, the impedance different between P+MM wouldn't a problem, am I right?
     
  10. In order for the behavior to be any different than having a passive bass, you would need a preamp with two individually buffered input. AFAIK, ACG preamps are single input, as are the vast majority of all preamps on the market.

    A viable option, however, is a buffered blend pot. IIRC, EMG makes one.
     
    SPYD3R #9 likes this.
  11. RobbieK

    RobbieK

    Jun 14, 2003
    The trouble is that to most bassists, the sound of a MM pickup is that bright stingray, snappy treble sound. The sound of a P pickup is the traditional thumping midrange Fender Precision tone. The thing is, those tones are as much a product of the other electronic components in those respective circuits as the pickup itself. A P pickup when buffered directly with a 1meg input Z from a typical buffer pre, really doesn't sound like a P pickup anymore. Especially in the treble. And a MM pickup, when run passive in series mode through a typical pair of 250K pots sounds nothing like a stingray. Again, especially in the treble.

    I've seen this MM and P in one bass idea many times, with the idea to be able to roll from a big warm precision tone to a bright stingray tone with your blend knob. I'm afraid if you wire this as a typical active bass with blend a pre and a vol, then you will be unimpressed with both pickups.

    I think the EMG active twin buffer blend thing is a great idea. This will get your MM pickup sounding nice and snappy. (BTW, in parallel mode it will read more like 2K, not 8K.) But to get the P sounding more traditional it needs to "see" a much lower Z loading from the buffer. You can do this in a couple of ways - or some combination of these. And you will have to experiment to get it sounding about right. One is to wire a passive tone pot to the P pickup. If there's no room, on the front, you could do this with a trim pot inside the bass so you could tweak it if you need to. (Be aware that most of the tone roll-off action will be in the first quarter turn of the trim pot because these are linear, not log taper, like a traditional passive tone pot.) You can also simply add some parallel resistance and/or some capacitance across the P pickup/buffer input. This simulates a couple of pots, and the capicitance of a typical guitar cable. I would think if you used a 100K resistor and a 1nF cap you'd get pretty close to a traditional P Bass tone.
     
    SPYD3R #9 likes this.
  12. Skelf

    Skelf Supporting Member

    Apr 15, 2005
    Moffat D&G Scotland
    Disclosures:
    Builder AC Guitars.
    I combine my own PB split coil pickup with RFB MM style humbucker all the time. Both pickup inputs on my preamps are buffered. It is a dual input preamp because each pickup has its own lowpass filter so requires an input from each pickup.

    Both pickups sound as I would expect them to. Nice fat low end from the PB and the more aggressive RFB just blending from one to the other. The lowpass filter for each pickup also allows to further manipulate both pickups to reduce or increase the difference between the two pickups.
     
    Last edited: Feb 12, 2015
    SPYD3R #9 likes this.
  13. Hi Alan, I use your ACG EQ-02 and it only had one LPF for both pickup, the config are vol-blend stack, LPF stack, HPF stack, passive tone
    I want to use the ACG preamp with nordstrand NP5+MM5.2, will it cause any issue?
     
  14. Skelf

    Skelf Supporting Member

    Apr 15, 2005
    Moffat D&G Scotland
    Disclosures:
    Builder AC Guitars.
    The inputs are both still buffered. No issues that I am aware of.

    Alan
     



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