wiring on JB Bass Pickups

[PolyurethaneCow]

Hello -

I was wondering if i could get an answer to a wiring question. I just bought a set of new USA JB bass pickups0 from the G&L online store to put in my jazz bass. The bridge pickup has the expected wire colors (black for ground, white for hot), but the neck pickup wires are red and yellow. Can anyone definitively tell me which is the ground and which is the hot, the red or the yellow?

The pickups did not come with any wiring diagrams, instructions or documentation. Thanks for your help!!

[Ken Baker]

Definitively? No, as I do not have a current diagram for either the JB or JB-2. I'll get the question off to Paul to see if he remembers or has a diagram.

In the meantime, general wiring practices would have the red as the hot lead. You could try that if you want. If it isn't correct, the pickup pair with both at full volume will not hum cancel.

Edit a few minutes later.

Per Paul, red should be hot.

Ken...

[PolyurethaneCow]

OK. I tried red as the hot lead and yellow as ground. In the exact center position (i have a blend pot installed - master volume setup) I am losing a lot of low frequencies, like they are wired out of phase or something. But only in the exact dead center position. as soon as I move the blend pot even a millimeter off the dead center, all the lows come back. That's why i kind of wanted to check to see if i maybe wired them backwards.

Thanks for the help!

[Ken Baker]

Okay... I've started with a little housekeeping here and moved this to the Experimental Bass Association. Why? You're grafting G&L pickups into a non-G&L bass. It's not a problem; it's all about location, location, location.

Secondly - I don't have your bass in front of me, so this is educated guesswork.

OK. I tried red as the hot lead and yellow as ground. In the exact center position (i have a blend pot installed - master volume setup) I am losing a lot of low frequencies, like they are wired out of phase or something. But only in the exact dead center position. as soon as I move the blend pot even a millimeter off the dead center, all the lows come back. That's why i kind of wanted to check to see if i maybe wired them backwards.

Some things come to mind here:

That the lows come back when moving off center indicates a phase problem to me. As you probably suspect, one of the pickups might be connected backwards. It's now 3:45PM PDT and I just heard back from Paul again. He went digging into a bunch of docs and found that the red lead is ground. Doesn't make sense from an electrical logic sense, but that's what we've got for this one.

Did you use a traditional blend pot or a "smart" blend pot? A traditional blend pot, or "pan pot", uses a pair of bog-standard pots and adds a center detent. This means that at the center detent both pickups are seeing some resistance from the pots, which is like cutting their volumes. A "smart" blend pot is designed to have zero ohms resistance at the center detent. I understand that the Fender-branded pot is of this "smart" design.

Jazz and Jazz style basses that use a standard circuit typically have 250K pots in all locations. Using 500K pots will work, but you'll have more high frequencies come through. In your case, you'd want to make sure that the blend pot is 250K, and that the volume and tone pots are 250K audio taper. This will give you the warmest tone.

Ken...

[PolyurethaneCow]

Thank you for researching further!

The Blend pot is a 250K Bourns pot - i am not sure, but i believe the Bourns pots are "Smart" taper. According to their documentation, there is no resistance at the center position:

http://www.bourns.com/docs/ProAudioDocs/bourns_pdb182_blend_balance_gtr_pots_appnote_for_bass.pdf?sfvrsn=15

The other pots are all 250K (Audio taper for volume, Linear Taper for tone).

So it does sound like the Yellow wire is the hot, then, and should go to the blend pot, while the Red wire Goes to ground. So it woudl appear that I do have it wired backwards.

Thanks - i will try switching them out!

[PolyurethaneCow]

And that was exactly the problem. Switched the yellow and red wires and everything is working perfectly now.

Thanks Ken! and please thank Paul for me for his help in researching this!

[Ken Baker]

Excellent! Glad we were able to help, even if it took a couple tries.

Ken...