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1 Vol 1 Tone wiring diagram for PJ Bass

Discussion in 'Pickups & Electronics [BG]' started by Mark Ambler, Nov 18, 2017.


  1. Mark Ambler

    Mark Ambler

    Nov 18, 2017
    London, UK.
    What I want to do is probably very simple, but I don't understand how wiring pickups work, but I can follow a diagram ok. I have a Vintage Modified Precision and I've replaced the stock P pickup (which suprisingly was Alnico) with a 2015 American standard Precision pickup and the bridge with a Vintage noiseless Jazz bass pickup. The bass sounds heaps better, and I'd like to try having a master volume and a master tone control, but I haven't been able to find a diagram. Can anyone help? Many thanks.
     
  2. Eric ER and Mark Ambler like this.
  3. Mark Ambler

    Mark Ambler

    Nov 18, 2017
    London, UK.
    Thanks for that. So to clarify, I just solder the white wire from the Jazz pickup to where the white wire from the P pickup is, and the black wire from the Jazz pickup to where the black wire from the P pickup is.
     
    Last edited: Nov 18, 2017
    Killed_by_Death likes this.
  4. Bourbongangster

    Bourbongangster

    Nov 5, 2015
    If you wire up two pickups with only one volume, then you are wiring them in series rather than parallel. It will change the sound quite a bit, but in a good way IMO. All you do is solder the positive wire on one pickup to the negative on the other pickup. Once you do that,you can think of the two pickups together as one pickup now. Then just find a basic P-bass wiring diagram and put your new "one pickup" where the P-bass pickup is in the diagram.
     
    Mark Ambler likes this.
  5. The OP has the option to wire either series or parallel. Either option is perfectly doable, and quite simple.

    I don't see any reason to wire in series, however. Most people dislike the sound of a P and J in series, and it is not the same as the way that the pickups are currently wired.
     
    Mark Ambler likes this.
  6. Bourbongangster

    Bourbongangster

    Nov 5, 2015
    Thanks for the correction Line6man. You're the man when it comes to this stuff. I never knew that you could wire up two pickups in parallel with one volume. So then you just solder the + wire of each pickup to the same lug on the volume pot?
     
  7. To have them in parallel, which is standard, yes.
     
    Mark Ambler likes this.
  8. Yeah. You just connect both hot wires together.
     
    Mark Ambler likes this.
  9. Bourbongangster

    Bourbongangster

    Nov 5, 2015
    How bout that you learn something new every day. Thanks!
     
  10. Mark Ambler

    Mark Ambler

    Nov 18, 2017
    London, UK.
    Ok, I wired both hot wires together, and it worked as expected (sort of). The volume control on full is 100% but volume falls back way too quickly. Would I be right in thinking this is because it's an audio pot? If I use a Linear pot the increase in volume should be 'smoother', or perhaps there is something else I should do?

    Edit

    In this one vol one tone configuration, should I use a 500k pot instead of a 250k?
     
    Last edited: Nov 21, 2017
  11. If you're going to change that one pot to 500k Ohm, go ahead & change the treble cut pot to 500k Ohm as well, but...

    keep the Audio taper for the treble cut, and I'm not sure Linear taper would be what you want either

    Here is the difference:

    potentiometer_taper.png

    If you change both pots for 500k Ohm, you should notice more brightness.
     
    Mark Ambler likes this.

  12. Typically the best behavior comes from a linear volume and audio tone control.

    Did you wire the volume pot properly? For a master volume, the middle terminal should be the output. This is in contrast to the "backwards" wiring of basses with multiple volume pots, where the middle terminal is the input.
     
    Mark Ambler likes this.
  13. Mark Ambler

    Mark Ambler

    Nov 18, 2017
    London, UK.
    On this diagram I have moved the white bridge lead to the where the white neck lead is attached. https://www.seymourduncan.com/wp-content/uploads/2016/05/P_JBass_Standard.pdf
    Are you saying I should swap the black and white leads on the neck pot lugs?

    Also, re different pot values, would I need to use a 500k for tone if I was using a 500k for vol? My (probably wrong) logic was as there were two 250k pots, with only one vol it should be 500k?
    Thanks everyone for the help.
     
  14. Josh Kneisel

    Josh Kneisel

    Jun 17, 2016
    Arizona
    not trying to derail or be off topic, but isn't it better to just run a pot with a middle indent and have it blend the two pickups and have a separate tone knob for each pup? Like all the way toward the neck is all P, in the middle is both at full and all the way toward bridge is J pup and tone of both pups is independent? that's how mine is anyways....
     
    Mark Ambler likes this.
  15. If the OP wanted to blend between pickups, the original V/V/T configuration would have been best for that.

    If you're working with only one volume pot, I don't think it matters (electrically) whether the output comes from the center lug or the input goes there.
    It does matter when you have 2 or more volume pots.
    (add: ok, so it can affect the taper, try switching the wires)

    If you want to experience more brightness, change both pots to 500k Ohm.
     
    Last edited: Nov 21, 2017
    Mark Ambler likes this.
  16. honeyiscool

    honeyiscool

    Jan 28, 2011
    San Diego, CA
    I may be completely wrong here, but here's now I understand it.

    Let's say we have a pickup that is exactly 10k resistance. Let's say we have a linear pot that is 500k resistance. And at 5, you have exactly 250k between the outer and inner terminals. At full on, they act exactly the same. But they act differently at other positions.

    In a regular volume knob, at 5, input to ground is always 500k, output just taps into that and gets closer to ground. So, let's say you measured the resistance from output to ground. At 10, it would be 500k from the pot combined with 10k pickup in parallel, so about 9.8k. At 0, there would be no resistance from output to ground. At 5, you have 10k from the pickup, which still sees 500k combined resistance on its way to ground, so that still reflects a 9.8k load, and since the output is halfway between the input and ground, resistance of output to ground would measure 4.9k.

    In a reversed volume knob, you have a very different situation. At 10, it's the same. But at 0, there is no resistance from input to ground, but there is still 500k resistance from output to ground, and if you stuck a multimeter, it would show that. Meanwhile, at 5, the pickup now sees a 250k load to ground in parallel, and that's about 9.6k. From input to output, you have a 250k load and that's in series, so if you measured output to ground, you'd see 259.6k. So it's a completely different reading.

    In a passive tone circuit where literally anything can change anything, a reversed volume knob can have very marked tonal changes because of the added resistance as you turn down the volume knob. And at the very least, you're not giving your pickup a constant load, so you would expect it to get darker much more quickly than in a regular volume wiring.
     
    Mark Ambler likes this.
  17. Yes, you will want to swap the black and white leads on the volume pot. This should improve your taper.

    You can use any combination of pot values you want. Just note that if you remove one volume pot, the remaining volume pot would need to be halved in value to keep the same load as you originally had with the two, if you decide that you want everything to sound exactly the same.
     
    Mark Ambler likes this.
  18. Mark Ambler

    Mark Ambler

    Nov 18, 2017
    London, UK.
    So I would need a 125k pot? I found a schematic for a 1 single coil pickup 50's Precision that used 1 250k so perhaps I will stick with that for the moment. I need to buy a simple electronics book that will explain the basics for me, any recommendations?

    I've come to the conclusion that if I want to change the vol, vol, tone setup, I need to go active, and my intention was not to spend a lot on a £300 bass. I already had a set of Fender Vintage noiseless pickups, so that was the bridge sorted, and I bought a P-Bass pickup which was from a 2015 USA standard Fender P, and the bass sounds pretty good now. I'm really liking the way the bridge pickup is nearer the bridge on my VM Squier Precision, a noticeable difference to the 'regular' positioning.

    This thread has been very informative for me and I really appreciate the info people have shared. Thanks!
     
    Last edited: Nov 23, 2017
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