Grounded polepieces vs. closed covers?

[Stealth]

Here's something that went through my mind as I was messing around with my first bass (which I still have, a cheap Fenderoid P/J).

Grounding the pickup poles using a copper strip on the bottom seems an age-old technique for eliminating some of the hum and buzz that appears in pickups - it definitely helps in case you hit a pole-piece with your finger. However, while watching one of Billy Sheehan's clinics, I noticed him mentioning his pickups intentionally having closed covers so his fingers wouldn't hit the pole-pieces - effectively eliminating the chance of hum in the first place.

So, what the heck - I took a bit of wallpaper (the plasticized, self-adhesive kind), cut out a few sized pieces and covered up the poles on both the P and the J. The result is quite interesting - since my technique and setup take after Sheehan's in many ways, I think I can safely say the "cover-up" worked fairly well - but I'm not sure if this really solves the issue in itself or if there's another benefit to grounding pole-pieces. Eventually (as soon as I rewind the P/J to my own specs), I will get around to grounding the ones I manage to manufacture, but I'm still wondering - is there something else grounding the pole-pieces can help prevent?

[David Schwab]

A closed plastic cover is not going to eliminate noise from ungrounded magnets/poles. That only helps if you get your finger close, but potentially it can be the source of other noise too.

I see no reason not to ground your magnets. people wouldn't have been having to cover the poles if Fender had grounded their magnets in the first place.

[salvarsan]

To eliminate conducted hum, connect the bridge+strings to ground through a parallel resistor+capacitor.

270k and .02uf/400VDC does it. Either value is approximate.

Look:
Guitar cavity wiring

-drh

[Old Tele man]

To eliminate conducted hum, connect the bridge+strings to ground through a parallel resistor+capacitor.

...that combination is also called a "ground-loop" break circuit.

[David Schwab]

Look:
Guitar cavity wiring

You have an Ovation Deacon? I always wanted a Bread Winner. I might build myself an updated version at some point. They are very funky guitars.

[salvarsan]

You have an Ovation Deacon? I always wanted a Bread Winner. I might build myself an updated version at some point. They are very funky guitars.

I have a disassembled old Deacon that was the template for the neck-through on the web site.

The large mahogany body is a sustain-soak for the high notes.
If you decide to make a Deacon shaped guitar, use a maple neck
and body cap, or a brighter tonewood than mahogany-like types.

-drh