P/J Bad sound when I turn both pickups up

[Enric Soler]

I play a p/j jaguar vintage modified squier (active) bass that has a vol/vol/tone/tone setup.

I changed the p-pickup yesterday (due to the fact that the old one just died) and it sounded great, the problem came afterwards, when I turn both volumes up E and A string sound bad (flatter, with no bottom end) while D and G sound well, but when I try the sound with only the P or the J pickup all strings sound ok.

I'm not sure which kind of problem it could be, (I guess it has to do with the pots) I didn't rewire anything when I changed the pickup.

Also I'm not sure if I had this problem before changing the P pickup but I reckon I would have noticed.


Does anybody know what kind of problem could it be?

[Thombas]

I'm not quite sure what you mean by saying it sounded great at first, but the problem occured when you turned up the volume? Anyways, my initial thought was pick-up hight - have you installed the new one lower than the old one? It could loose a little volume and maybe come out as "flatter".

[Zootsuitbass]

Phase cancelation, do search.

[Mogalen]

Same thing with my P/J bass. I only use the P pickup, and I'm changing the J pickup soon. I hope the new one can give me a better sound, with a freshly installed EQ.

[line6man]

Originally Posted by Zootsuitbass

Phase cancelation, do search.

Yep. This is a phase issue.

[Matthijs]

If the phase cancelation was not there before and you have ruled out stuff like pickup heigth, this might have to do with the polarity of the bass-side of the p pickup. Try changing polarity for the whole pickup first and then for just the E-A side. Is the P-pickup noisier than the pickup you had before?

[Duckwater]

Definitely phase cancellation. That's why I like P/J pickups spaced further apart.

[line6man]

Originally Posted by Duckwater

Definitely phase cancellation. That's why I like P/J pickups spaced further apart.

Pickup spacing has nothing to do with this. Pickup spacing changes the degree of phase separation, but wiring a pickup backwards creates a 180 degree shift over the entire signal, which cancels everything of equal amplitude.

[Matthijs]

Originally Posted by Duckwater

Definitely phase cancellation. That's why I like P/J pickups spaced further apart.

If the phase cancellation was caused by the pickup position alone the problem would have been there before. It sounds like the phase cancellation is mainly in the lower harmonics, so it might be a polarity issue. As far as I know p-pickups are wired much the same way as with 2 j pickups in series. The phasing for the lower harmonics should be the same for the D/G pickup and E/A pickup and for the bridge j and the P pickup.

[Denny Coon]

+1 on the 180 degree.. I installed a set of EMGs one time P/J, in small print it shows you have to flip the quick conects upside down to the P pickup to reverse the phase.. I didnt see it the 1st time around and had the same issue.

[Duckwater]

Originally Posted by line6man

Pickup spacing has nothing to do with this. Pickup spacing changes the degree of phase separation, but wiring a pickup backwards creates a 180 degree shift over the entire signal, which cancels everything of equal amplitude.

I didn't know that, thanks.

[Enric Soler]

Thank you everybody, I had done some research on it but I didn't know how it was called and my research didn't go well.

I'm gonna try and learn a bit about phase cancellation and solve it, many thanks!

[ctmullins]

It's a piece of cake to actually solve: Just swap the hot/ground wires on ONE of the pickups. Done.