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Volume only effects one pickup

Discussion in 'Pickups & Electronics [BG]' started by askgianni, Mar 3, 2014.

  1. askgianni


    Mar 3, 2014
    Let me start by saying that I'll pull the pickguard off my bass tonight and post some pictures of the wiring. But until then...

    I'm having trouble with my bass, a PJ setup by Samick:


    The knob setup is pretty standard: volume, mix, tone. When I have the mix knob turned all the way to the bridge (P) pickup, the volume works just fine. When the mix is towards the bridge (J) pickup, the volume knob doesn't affect the volume of the bridge pickup. So if I have mix knob right in the middle and turn the volume all the way down, I get the sound of the bridge pickup at half volume. Does that make sense?

    Any thoughts about what might be off with the wiring that would cause this behavior? Like I said, I'll post a picture of the wiring tonight if that helps. The bass isn't worth enough that I want to pay to have this looked at. I'm willing to get out the soldering iron and go at it myself if I can get an idea of what the issue might be.
  2. That behavior would be explained by running the P pickup to the wiper terminal of a volume pot, and then running one of the outer terminals to the P pickup's input on an A/C taper blend pot. The volume only works for the P pickup, because it's wired for the P pickup only, rather than as a master volume. If the P pickup is muted, and you go to the center detent on the blend, the volume drop there is caused by using a cheap A/C taper blend that attenuates the pickups at the center detent, rather than running both pickups directly to the output.

    What you need to do is follow a standard VBT wiring diagram, and get an M/N taper blend, for the best performance.
  3. askgianni


    Mar 3, 2014
    Thanks for the reply line6man, your response made me stop and think, maybe this bass is simply wired VVT not VBT :) So I looked up the specs and ta-da! that's what it is. So it's clearly a lack of understanding of how to operate my equipment. Interestingly enough, I've been playing this bass for two and a half years and I realized that when I first started playing it, I knew that it was set up VVT -- not sure how I lost track of that.

    Anyway, thanks for helping me get my thoughts back in order.