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Bart J Polarity?

J. Brunka

J. Brunka

Aug 9, 2004
146
64
Mo'town, N.J.
#1
I have a MIJ Fender Jazz I bought used that came with Bartolini active pickups. The controls are blend, volume, tone. Since I have had it the bass works great when one pup is on but when blending both of them the volume dies as if there was a phase or polarity problem.

I have taken the bass apart and checked the wiring based on some diagrams I found here and at Bart's site. Everything seems fine but I am far from an expert (I play mostly upright).

The only other info I can give is that I hear a little bit of noise as I start to turn the blend pot out of full left or full right position. I don't know if this means I should replace the blend pot or is this a more common problem due to faulty wiring that I haven't been able to detect.

Thanks in advance for the help.
 
#2
J. Brunka said:
I have a MIJ Fender Jazz I bought used that came with Bartolini active pickups. The controls are blend, volume, tone. Since I have had it the bass works great when one pup is on but when blending both of them the volume dies as if there was a phase or polarity problem.

I have taken the bass apart and checked the wiring based on some diagrams I found here and at Bart's site. Everything seems fine but I am far from an expert (I play mostly upright).

The only other info I can give is that I hear a little bit of noise as I start to turn the blend pot out of full left or full right position. I don't know if this means I should replace the blend pot or is this a more common problem due to faulty wiring that I haven't been able to detect.

Thanks in advance for the help.
Click to expand...

FWIW:

It's definitely possible (especially given that would be the control configuration per Bart diagram) but it's unlikely the Barts are active 1) becuase they don't show often and 2) Bart has made very few active pups let alone active J's. If it's the current 9E J set then in fact, the neck pup in that set is actually passive with the bridge pup containing the preamp. If there's not a half dozen wires coming from the bridge pup including a red lead going to the battery, it's not a 9E J set. And if there's not a lead (invariably red) coming from the pups that runs to the battery clip they're not active at all, at least in my experience. There's a wiring diagram for the 9E set on their site.

At any rate, polarity is the issue from your description. If there's only two leads coming from each pup (probably a tranpsarent hot lead and braided ground) they're passive and the leads on pup just need to be switched.

I have read of some blends that seem to yield a similar complaint but you should get the same response from a blend as two volumes otherwise. Also there could be some screw-up in wirng of the blend - especially if those were not original, which I'm guessing they're not.
 
#3
Yes, they definitely are the 9E set. The wiring is correct as per the diagram on the Bartolini website with the exception of a blend control and one volume instead of two volumes.

Do these pickups work in blend? I am coming close to taking out the blend pot and wiring it exactly like the diagram, but would like to know if it just isn't possible or if the blend pot is faulty. Has anyone put a blend on these pups? Does it give a different sound then the two volumes?
 
#4
J. Brunka said:
Yes, they definitely are the 9E set. The wiring is correct as per the diagram on the Bartolini website with the exception of a blend control and one volume instead of two volumes.

Do these pickups work in blend? I am coming close to taking out the blend pot and wiring it exactly like the diagram, but would like to know if it just isn't possible or if the blend pot is faulty. Has anyone put a blend on these pups? Does it give a different sound then the two volumes?
Click to expand...


Blend controls are wired pickup to center lug of the respective pot. The outer lugs of the neck pot crisscross to the outer lugs of the bridge pot. One outer lug connects to ground of the bridge pot while the other lug is the collective signal output. The Blend pot works by: As you turn it in one direction the signal from the Neck pup increases while the signal from the Bridge pup decreases proportionally and visa versa. The only thing I can see is that either the blend pot is wired incorrectly or possibly even one of the pickups. If the Blend pot is correct then try reversing the Neck pickup to the blend pot. If this makes things worse then put it back as it was and try reversing the leads of the Bridge pickup to the blend pot.
Please let us know what you find.
-Gary
 
#5
FWIW:

If I had a another volume pot laying around, I would wire it with two volumes just to simply things. There's no doubt the crossovers on the blend can get screwed up, they're a pain to wire even when done correctly (and so prone to defect from the outset), there's no place for a good ground connection on them (and that could be part of the problem), blends seem more prone to manufacture defect, and they're more difficult to trouble shoot. There's a steady flow of this same complaint in this forum and that should say something. With the that pot and pup combination, you comparatively have a pair of freaks in their relative worlds.

Technically, you should get the same response with a volume you're getting with the blend. I'd stick another volume in it and if I got the same response I'd conclude the blend isn't the issue and was fine, if the second volume resolved the issue then something's going on with the blend.

You could jack with that blend for a long time and be no further down the road.

When trouble shooting, make it simple.

Another thing I would double check is that the red leads aren't crossed around. That's unlikely and I doubt it would cause this issue if it were so but there's two red leads on that pup (one preamp that should be alone outside the jacket)and connections are external so anyone could tac any of those leads wherever they wanted to. I seriously doubt these are stock pups which means somebody's been jacking with the bass in the past.
 

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