Thunderbird with Lull - Ground Issue Wiring Questions

[stiles72]

I put a Lull TB pup in the bridge of my Epiphone Thunderbird, and for the longest time I couldn't figure out why when I turned both pickups up, the volume dropped in half and sounded weak and tinny. Roll one or the other volumes off slightly, and the other would jump to life.    I was looking at the TV Jones site (makes of the Lull pups) and read that:

"If you buy a TV Jones pickup and combine it with another pickup on your guitar and the resulting sound is thin or "banjo-like" with no lows, your pickups may be out of phase.  TV Jones pickups are reversible. You can simply reverse the black & white wires (black=hot white/shield=ground)."



So I tried this, swapping the black and the white - and voila - you can now turn both pickups on full and the combined sound is as it should be.  However, in order to get it to work - I had to leave the bare/shield disconnected. When it's connected as it should be to the pot - no sound. But otherwise - it works just fine. The problem I'm having, is that when I play the Bird through amps that have an old school 2-prong cord, if you touch the Lull pup, it buzzes like crazy. Throwing the polarity switch on the amp helps but still buzzes badly. On my modern amps with three prong cords, there is no buzzing issue.  Any idea what can be done? I tried connecting that shield wire to different locations - but everytime the signal cuts out.

[jumbodbassman]

put the lull pickup the original way and switch the other Artec?

[Psycho Bass Guy]

I suspect you've actually wired your pickups OUT of phase, which with basses with large distances between the pickups, can sound better. Try wiring the shield to the reversed "hot," the black wire.

[stiles72]

Thanks -

Tried putting the Lull back to original, and reversing the Epi pup. That just made the Epi pup not work.

Put the Epi back to stock, then put the Lull back to Black to hot, white to pot, and shield to hot terminal with the black. That didn't change anything - it still buzzes when you touch the pickup.

Seems like anytime the shield wire touches the pots, all signal is lost. Touch it anywhere else (such as a post) and the pup works, but you get buzz if you touch the pup itself.

I'm at a loss - maybe I should just put a piece of clear tape on the Lull where it gets bumped/touched to keep it from buzzing and just live with it?

[Lightyear]

Tried taking the Epi out of the circuit altogether?   I would be tempted to wire the Lull straight to the jack and make sure the pickup is OK - you could just have a bum pickup.

[Daniel_J]

I think the shield is somewhat connected with the ground wire. Maybe inside the metal cover both shield and ground wire (black) are welded together with the cover. That would explain why connecting the shield with a grounded pot kills the sound, because you are actually grounding the reversed hot wire (black) since black and shield are connected together.
It also explain why touching the metal cover creates a buzz, simply becasue it means you are actually touching the hot wire (black) that is connected with the actuall cover.

To be sure about it, disconnect both wires and shield, and if you have a multimeter you can measure the original ground wire (black) and shield to test if there's a short. If you don't have a multimeter you can just swap the black wire with the shield. Meaning you have to disconnect the black and swap for the shield. If it works the same, then it means that ground wire (black) and shield are connected together inside the cover.
If that's the case, then you have to take the pickup apart and swap the wires inside the cover.

[dadagoboi]

If it helps, original TBird pups have both the "black" and the braided cable (ground) soldered to the outside of the bottom plate...  Ditto for ThunderBuckers.

[ThunderBucker]

Yes it sounds as if your Lull pickup has an internal connection between the black wire and the can, meaning that you can't reverse the phase connections without leaving the can connected to the pickup hot output.  That would cause all kinds of buzzing when you touch it.  Confirm this with the ohm meter, that one of the output wires is in fact permanently connected to the case of the pickup.  If that is so, then the pickup must be connected so that the case side is ground. 

And the other pickup must be phase reversed so that it sounds good.

[stiles72]

Thanks - I'll check that out and report back...

[jumbodbassman]

any luck???