Another "would this work?" thread

[birminghambass]

I have a Fender PJ with Duncan QP pickups. Sounds good but since the J is single coil it hums constantly and it's driving me nuts! I was thinking about routing under the pickguard for a "dummy" jazz pickup. I would wire the dummy jazz series or parallel (not sure which would work better) with the bridge jazz to eliminate the hum. Would this work? Would this change the tone of the bridge J?

[StonewallValent]

You theoretically could do that, but I seriously recommend against it. It would be much simpler to get a split-coil J pickup. You wouldn't need to route anything out, it would be just like tossing different shaped P pup in your bass.

[birminghambass]

Simpler yes. I really like the tone of the QP P pickup and I've yet to find a split coil J that could even come close to it in volume.

[R. Laevinus]

You could do that, yeah. It might change the tone a little, but probably not much. Another QP would probably be your best bet. If you porked the magnet off the dummy pup before installing it, it would help keep extraneous noise down.

[Shoewreck]

This will work. Series connection seems more reasonable to me (you won't lose volume this way). The tone would get a bit thicker.
You may try degaussing the dummy pickup (by approaching a repelling rare earth magnet to it's pole pieces, works extremely well with AlNiCo) to further minimize it's effect on sound, since degaussed pickup won't sense string vibration. Hum cancellation would remain.

[4StringTheorist]

Duncan Hot Stacks J, maybe?

[line6man]

I would definitely recommend just opting for a humcancelling J pickup.

[walterw]

yeah, traditional dummy coils extract a pretty significant price in tone loss in exchange for their hum-canceling.

i'd recommend a side-by-side hum-canceler, like a dimarzio ultra jazz. the QP P pickup is still gonna be stronger, but side-by-side designs are inherently louder than stacked designs, so the balance will not be quite as far off.

[line6man]

Originally Posted by walterw

yeah, traditional dummy coils extract a pretty significant price in tone loss in exchange for their hum-canceling.

Well, I tried a dummy coil on my bass the other week, and I was pleasantly surprised at how close it sounded to my original tone.

Of course, placing the dummy coil parallel to your audible pickup drops the output impedance, which means you lose some volume, but once I adjusted the gain on the preamp I play my bass through to compensate, it sounded fine to my ears.

My next project (And I have a habit of starting projects and not finishing them.) might be to try buffering the pickups and summing them together to both lower the total output impedance, and prevent any changes in the audible pickup's LCR.

[walterw]

Originally Posted by line6man

...once I adjusted the gain on the preamp I play my bass through to compensate, it sounded fine to my ears

this is the usual answer to the dummy coil "problem", to pair it with a preamp to make up the loss. everybody from alembic to music man to EMG does it this way, and it works just fine.

i think of the bottom coil of a stack as a dummy coil, and note that most of the time these get addressed the same way; for example, fender almost always pairs their stacked jazz pickups with onboard preamps.