MIMF

This probably falls under the "It ain't broke, so spend hours and $10.00 fixing it" heading on my part. Case in point:

I'm wiring up my hybrid Steinberger bass. I'm re-using all the electronic guts from the original source bass, which was a Steinberger XP2, and not notably noisy to begin with. It has two EMG passive humbucking soapbar pickups. There is no pickguard, so the two pickup cavities are not connected other than both having wire channels to the control cavity.

I have lined both the control cavity and two pickup cavities with copper stick-on foil, maybe that was complete waste of time for humbucking pickups, but I figured it can't hurt anyway. I also foiled the back of the control cavity cover, which will be in contact with the cavity foil at the screws that hold the cavity cover on.

My plan was to solder wires to the foil in each pickup cavity and run them to the blob of solder already serving as ground on the back of the volume pot. The volume and tone pots will be in contact with the control cavity foil where the pot shafts pass though it to exit the body, so I assume I don't have to solder a wire from the control cavity foil to the pot.

There is a ground wire running to one of the bolts for the bridge.

I have read through all the conflicting opinions on "star grounding", and the consensus seems to be that it is a waste of time, since the only path to ground in a guitar is through the output jack, which the volume and tone pots are daisy-chain grounded to anyway.

Any suggestions, am I missing something here? I admit I'm essentially clueless when it comes to electronics. I can wire stuff up and solder well in pure "paint by the numbers" fashion, but the theory of what is going on eludes me, particularly when it comes to how grounds work.

You do not need to shield the pickup cavities, as these pickups are internally shielded. But since you did add foil, just make sure it's all grounded.

I do not rely on the contact between a pot and the shield to maintain continuity. The best example I can bring up is the old Stratocasters which used the aluminum shield to ground the pots (and the pick-ups) and did not have a wired ground to the output jack. After some playing and sweating, the guitar would start to snap crackle and pop. Tying the pots to the ground side of the output jack made everything right.

In your case I would solder the shield from the pick-ups along with the wire from the cavity shield to its volume pot, tie all the pots to the ground side of the output jack, and tie the shield to the ground side of the output jack, as well.

The pots are all daisy chain wired to the output ground with wire soldered to the pot backs. Couldn't I just solder a wire to the control cavity and pickup cavity foil and wire to the back of the volume pot?

You could, and that would leave just two leads going to the jack. If you leave a bit of slack in those two leads, it will be easier to remove the jack when (and if) it needs repair.

Nice to see you post again, David.

I just had friend take his guitar in to a repair shop (he does not live in may state I did not do the work) because he has humbuckers but he though it was just a little bit to noisy and he had the shielding work and now he said it is much quieter. I don't if it was placebo effect or not but the recording of the before and after was quiter.

When in doubt ..........shield............ too much will not hurt anything. I have worked as a electronics technician for 39 years so I speak from experience.