P bass copy with humbucker - wiring issue

[JACK250]

Hi all, picked up this Session by 'Riverhead sound research' P bass copy, which while only being a cheap 80's copy actually plays really nicely and I'm happy with it. Only issue being the knob set up has got me a little confused - it seems that each knob is a control for a pickup, as below:

My issue is, that if either pick-up is on completely I have no issue, but if I try to blend them, it sounds as if certain frequencies are being blocked, for example a g on the e string would come through loud, while an open g would be less than half the volume. is there a way I can perhaps rewire it so that I have 1 knob to control volume and one that is one of those pots that in the middle is blend, and you can turn it toward the bridge or neck?

 

[gunlak]

try to adjust the pickup height.

 

[JACK250]

I doubt it's related to the pickup height, because if I was on either the neck or bass pick up only, say an open g string as opposed to the exact same note on the 10th fret of the a string it will be the same volume, and if I blend the 2 pickups the one on the a string will be loud and the open string not.

 

[Stealth]

First off, the pickups might be out of phase - that is, one of them has the swapped lead and ground, which causes more frequencies to get cancelled. If the sound is very thin when they're both on, that's the problem. The solution is to take the hot and lead of one of the pickups and swap them by unsoldering the pot ends of the wires and switching their places.

Yes, it can be turned into a vol-blend setup. Use [Invalid or Expired Link Removed] as a guide.

 

[SGD Lutherie]

It sounds like half of the P pickup is out of phase with the bridge humbucker. So when you have the pickup at equal volume, the top strings have their volume and low end diminished, while the low strings are fine.

To fix this, you need to reverse the two leads coming off just the treble coil on the P pickup.

You will one of two scenarios.

If it's wired up like a real P bass, i.e., two wires from the pickup, you will see that one wire is going to the low string coil, and the other to the volume pot or ground. You will need to disconnect the wire from the other coil. This could be tricky and there is potential to damage the pickup. On a real P type pickup the lead is soldered to a brass eyelet on the bobbin. The very thin magnet wire from the coil also goes to that eyelet. You wold either have to unsolder the lead, or cut it off leaving enough wire to splice on the other wire.

Either way if you are not comfortable doing this, you might want to bridge it to a good tech.

The other scenario is that they used 4 conductor wiring, like DiMarzio does. If that's the case, disconnect where the two coils connect together, and swap the two wired from the treble string coil.

That would be a lot easier.

You might also want to just replace the pickup.

But, this is assuming that they are out of phase.

 

[Stealth]

I wouldn't say that's the issue, as in the first post the OP mentioned it happened on the G string, then in another post that the same happens on the A string, so those are definitely different P coils, yet they both sound thinner. It still sound like the P-pickup as the entire unit needs to have its leads swapped (or the JJ).

Also, SGD, if the P pickup as a unit by itself sounds fine, can half a pickup go out of phase with the other pickup, humbucker or not? That sounds like it'd make PJs sounding much worse than they do.

 

[SGD Lutherie]

I wouldn't say that's the issue, as in the first post the OP mentioned it happened on the G string, then in another post that the same happens on the A string, so those are definitely different P coils, yet they both sound thinner. It still sound like the P-pickup as the entire unit needs to have its leads swapped (or the JJ).

Hmmmmm... This is what he said that I was going by:

for example a g on the e string would come through loud, while an open g would be less than half the volume.

But if the entire pickup were out of phase, all the strings would sound thin.

But then, playing a note up on the neck, on a thicker string, like an A, will be louder than an open G.

Before we think pickups, when were the strings changed last?

 

[JACK250]

Hmmmmm... This is what he said that I was going by:



But if the entire pickup were out of phase, all the strings would sound thin.

But then, playing a note up on the neck, on a thicker string, like an A, will be louder than an open G.

Before we think pickups, when were the strings changed last?

Yes I should have been clearer, it is definitely on the D and G strings that the problem is obvious, the point I was trying to make is it seems more like a string thing than a frequency related issue.

Brand new fresh strings on it.

Thanks a lot for the responses guys, I'll most likely swap that wire and see what happens..