Strange pot problem...twice in 2 weeks!

[capnjim]

I never ran into this problem before, and now I have 2 basses that do it. I just scored an awesome Peavey Foundation. The seller had all new pots installed, 500K alpha, they work fine, but when both PUP;s are on full, the volume drops, like they are cancelling each other out. The wiring is fine, wired like a standard Jazz bass. I had another bass do this when I tried installing a new pot. Both PUP's work fine individually, but when both pots are wide open, the sound dies. Anyone experience this before? Would switching which pot post is grounded help? The wiring looks fine according to and diagram for a jazz bass.
Thanks

[line6man]

Sounds like insertion loss.

Is the tone thin and nasal? That would indicate a phase issue.

[capnjim]

Yes..when both are on full...very thin. When I use neck PUP pot, its instant..not linear at all. Almost like it was a switch.

[SamanthaCay]

This is not a pot issue.
It's possible that your coils are out of phase.
When this is the case you will have a significant drop in volume and low end when both pickups are combined.
The solution is to reverse one of the coils by switching its ground lead for hot and its lead for ground

Another possibility is that it is simply the nature of the beast.
Two pickup basses are most often wired in series, that way when both pickups are used together you end up with a humbucking effect.
The side effect of this is a very slight drop in output when both pickups are used together.

A way to get around this is to wire them in parallel but then you lose your humbuckingness.

[capnjim]

Its not the nature of the beast as I have another Foundation that is wired the same and it sounds great. I'll try reversing the wires from the PUP's, but they are black and red so you would think red would always be hot.
I'll break out the iron and give it a try. Too bad the dude didn't save the original pots.

[mech]

Peavey Super Ferrite pickups use the same coil and magnet structure for the bridge and neck pickups but they are magnetized opposite polarity. One pickup should use the red wire for hot and the other uses the black wire for hot. Doesn't make any difference which is which.

mech

[MNAirHead]

Thanks mech - a while ago I ran into tonsof this stuff

[capnjim]

Yeah Mech..I bet thats it! Thanks.

[Ken R]

Panama Red - YouTube

Somehow I thought this what you were referring to.

[walterw]

Originally Posted by buchananbass

This is not a pot issue.
It's possible that your coils are out of phase.
When this is the case you will have a significant drop in volume and low end when both pickups are combined.
The solution is to reverse one of the coils by switching its ground lead for hot and its lead for ground

yep.

Originally Posted by buchananbass

Two pickup basses are most often wired in series, that way when both pickups are used together you end up with a humbucking effect.
The side effect of this is a very slight drop in output when both pickups are used together.

A way to get around this is to wire them in parallel but then you lose your humbuckingness.

nope, not even close.

two-pickup guitars and basses are usually wired with the two pickups in parallel, not series. two pickups in series causes a volume and low-end boost, not a drop.

neither one has anything to do with whether they cancel hum or not.

hum-canceling happens when two single coils are opposite magnetic polarity and opposite winding polarity from each other; they cancel hum whether they're in series (P-bass) or parallel (jazz bass, stingray).