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Greco p/j bass pickup strangeness

morgansterne

morgansterne

Geek U.S.A.
Oct 25, 2011
2,075
1,691
Cleveland Ohio
#1
I got this a month or so ago here on talkbass. A beautiful 32" scale passive PJ.

I like the sound of the P pickup, and the bridge J is ok. But together, they sound bad. If you have the neck pickup full, as you dial in a little of the bridge, you just lose bottom end, without gaining treble. With both on full, you have a strange sound that I can't imagine is anyone's taste.
(I've never had a PJ before, but I have a dual P that behaves as I think they're supposed to -- a little bridge pickup gives you extra treble, a lot gives you a scooped jazz bass style sound.)
I've tried lowering the bridge pickup as much as I can, to ensure I'm not getting magnetic pull deadening my strings. My only theory is that the pickups are too close together to make this sound work.
Thanks for your help and suggestions!
Screenshot_20180424-140614.png
 
#6
Recently I installed new pickups in the bass in my avatar. The P pickup sounded great solo. The J pickup sounded like a J pickup at the bridge does solo. Together they sounded thin and crappy. The single coil at the bridge had more low end than both pickups did together. So, I was about 99% sure they were out of phase.

Here's what I did, since I didn't have the proper tools to test it. It did confirm that my pickups were out of phase. I know you don't have exposed poles on your pickups, but I'd think this test would still work. Taken from another helpful forum:

Using a PC Instead of a Meter

Instead of a meter, it is possible to use a PC instead to sense the pulse.
  • Plug the guitar directly into the PC line-in, a standard (eg sound-blaster) card is fine.
  • Record the signal into a suitable audio program, eg Audacity, which works well and is free
  • Lay the tip of a screwdriver flat on each pickup pole, then lift it up sharply away from the pickup,
  • The signal trace, recorded and visible on the screen will initially jump up or down when lifting the screwdriver tip

I did this test using two pickups. The top trace has both pickups in phase, while for the lower one, I operated a phase reverse switch on one pickup. You can see clearly how they are out of phase in the 2nd trace, because one signal jumps up and the other down (as would be observed on a meter):
blips.gif
 
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#7
morgansterne said:
Aren't the two pickups in a Precision set out of phase with each other? So I would think with this pickup config the bridge is always out of phase with one and in phase with the other?

I had never thought about that before today.
Click to expand...
I'm under the impression that phase doesn't really matter for both halves of the precision pickup when the pickup is soloed. This is because each string only passes over one pickup half, so phase cancellation won't happen (someone please correct me if I'm wrong). But, with another pickup in the mix, you want to make sure that both halves of the p pickup and the bridge pickup are all in phase with each other.

When I did the screwdriver test in my post above, my precision pickup halves were in phase with each other (my signal jumped up for both halves). But, my single coil at the bridge was out of phase from them (my signal jumped down). So, I switched two wires on the bridge pickup and now everything sounds as it should.
 
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#8
morgansterne said:
Aren't the two pickups in a Precision set out of phase with each other? So I would think with this pickup config the bridge is always out of phase with one and in phase with the other?

I had never thought about that before today.
Click to expand...

Slater said:
This may be the case. @morgansterne , try swapping the hot and ground wires of one pickup only (the split-coil P is one pickup).
Click to expand...

I had the exact same problem with a brand new PJ. Do exactly what Slater said and you will be good to go.
 

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