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Wiring help - pot and capacitor values

Discussion in 'Pickups & Electronics [BG]' started by BassPuzzler, May 12, 2011.


  1. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    So I'm looking to wire a bass as follows:

    Nordstrand Dual Coil at the bridge position with a two-way switch to select series or SC. Nordstrand NP5 at the neck position. Each will have an individual volume knob. The tone knob will be for both.

    Random Questions:

    I want an on/on switch, yes?
    What values should the pots be? 500k or 250k?
    What value should the capacitor be? 0.1 uF?

    Thanks!
     
  2. Don't know re-switch. Does the pickup have instructions on how it's wired and what to use the switching options?

    Pots - 500k will be brighter sounding than 250k, take your pick
    Caps - 0.1 uF will have quite a lot of roll off, 0.047uF is the standard used these days, but use a higher value (ie 0.1uF) if you want more of a roll off, or a lower value for less of a roll off.

    Not very useful, I know, but it is really down to what you want to do.
     
  3. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    hrm. All these choices.

    From Stewmac.com: "Generally, 250K pots are used with single-coil pickups, and 500K pots are used with humbuckers."

    Would it be weird to have different value pots for each one?
     
  4. Not at all.

    250Ks are often used with single coils to tame their treble, but 500ks are used to preserve the treble and output of humbuckers.
    Some people prefer 500ks with singles for a clear output, and 250ks with humbuckers to mellow them out.
     
  5. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    One thing I don't really understand, is why shouldn't I just use 500k for all of them? Then, if I think it's too trebly, I can just turn it down. It's a variable resistor. The 500k knob can be turned down to 250k.
     
  6. You can, but for the volumes, the 250k setting will be quieter than with a 250k pot, because you would be placing 250k resistance in series with the signal path, in addition to the 250k parallel resistance.
     
  7. It doesn't work quite as simply as that.

    You have to take into account the resistance between the pickup and output, but also the resistance between the output and the ground.

    With the 500K volume on "full" you have nearly 0K between the output and the pickup, and 500k between the output and the ground. So more of the signal is preserved.

    With a 500K pot, turn to being half way (assuming a linear pot here), you have 250K between the output and the pickup, but also 250k between the output and the ground, so you loose more signal to ground (hence why the volume goes down)

    With a 250K pot on "full" you have about 0K between the output and the pickup, but you only have 250K between the output and the ground, so there is some loss to ground, not very much, and it's some of the higher frequencies.

    (If that makes sense)


    Edit - Line6mans answer is simpler :p
     
  8. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    He besieged me with science!

    Well in that case, won't the 500k pot still have a setting somewhere along its range where it ends up having the same output?
     
  9. No.

    The difference in output (volume) between the two will be minimal, the bigger effect, at equal volumes, is the loss of higher frequencies.

    However, the differences between the pots are hardly night and day, so we may be over thinking this for you :p .
     
  10. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    K I'll just use three 500k pots. :)

    What exactly do you mean by roll off?
     
  11. Reduction of high frequencies.
    Higher values have a lower frequency cutoff, and thus, more of a treble roll off.
    Lower values have a higher frequency cutoff, and thus, less of a treble roll off.

    Btw, Mohawk, you've said that both high and low capacitances give more roll off.:hyper:
     
  12. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    heh. so he did.

    K. I'm really not entirely sure, but I'll just go with 0.047 if it's the standard. Thanks guys!
     
  13. haha, so I did.

    In my defense, it was about midnight and I was half asleep at the wheel. Cheers for pointing it out, corrected!


    The higher the value, the more treble is bled off, so the tone dial will make it sound 'bassier'
     
  14. Oddly enough, while I was searching for Walterw's series Jazz wiring diagram to post in a thread, just a few minutes ago, I found a thread where I had posted while distracted, and you were the one that corrected me.:hyper:
     
  15. Haha, brilliant. 1-1 then?

    Best of 3? :p

    :bassist:
     
  16. BassPuzzler

    BassPuzzler

    Mar 29, 2011
    Nicely done guys.

    Speaking of wiring diagrams....:D

    Stewmac has a wiring diagram for a jazz bass which is basically what I am doing. Individual volume, and master tone. Except I'm gonna have a dual coil pup with an on/on switch to select series or SC. :help:

    Thanks for all your help so far.
     
  17. 4044630163_661f69db30_o.

    Pick your switching from this diagram, and wire the "output" of the switch to the wiper terminal of the pot.
     

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