Shielding a Rick Bass

[Gilmourisgod]

I searched through old threads, and as seems typical with any subject, found a lot of conflicting information and opinions on best practice to reduce 60 cycle hum inherent to single-coil pickups. I realize this has probably been flogged to death, but is there a clear consensus out there on what actually works? I found some old threads where John Hall weighed in on it, but he didn't seem to think it was worthwhile. Other than the bit of foil tape on the back of the pickguard, is there any attempt at shielding included in stock factory production? I've shielded Strats before with mixed results using conductive copper foil tape, "star grounding", etc., which improved but did not eliminate hum. After reading through all the threads, the closest thing I found to a common approach would be as follows:

1. Line pickup cavities and wiring routes with shielding paint or conductive adhesive copper foil, leaving "tabs" of foil lapping up onto the body at pickguard screw locations to contact pickguard shielding.
2. Tack solder copper foil joints at seams and test for continuity throughout.
3. Wire soldered connections between each area lined with copper tape and test for continuity.
4. Cover back of pickguard with copper foil.
5. Wrap pickup leads in copper foil or change t shielded cable (not sure how that would be possible without damaging pickups).
6. Bring all ground wires to one common ground lug (not soldered to back of pots) and wire to ground on output jack (mono jack).

John Hall said something about NOT letting the control pots contact the shielding on the back of pickguard or inside the cavities to avoid "ground loops". I will admit that my understanding of guitar wiring is rudimentary at best, not even sure what a ground loop is. Has anyone done a comprehensive tutorial or real world analysis of this subject? If it's worth doing, why hasn't Rick or Fender included shielding as part of standard manufacturing process? My Strat had a little strip of aluminum foil on the back of the pickguard that did nothing to shield it, as far as I could tell.
Advice or links to good info on this subject appreciated.

[aceonbass]

My Ricks have never been particularly noisy, but if you're having issues, you could try steps 1 and 4 with copper foil. This worked really well on a Fender Jag bass I had that just wouldn't shutup with the 60 cycle hum. If you do the pickguard, do the whole thing and not just part, otherwise it shows through on white acrylic. The pickup leads are shielded cable so no need there. One of the possible reasons I never get much hum is that at home and when playing out, all my gear goes through a Monster Pro 950 power filter/conditioner.

[Gilmourisgod]

Dane,
Thanks for the reply. I was kind of hoping you might weigh in as the resident electronics guru. I'm strictly a bedroom hobby player these days, and the wiring in my house must not be well grounded, I get awful hum and buzz with any single coil instrument. My G&L L2K has a big copper plate at the back of the pickup cavity, and all the grounds appear to be soldered to that. That bass does not hum at all, but the pups are humbuckers. Is there any use to the star grounding technique vs. ground wires soldered to pots? it seems like as long as everything ends up grounded to output jack it achieves the same effect? Depending on where you read, star grounding is either crucial or useless, hence my confusion. Is it OK for the pots to touch the pickguard foil via the nuts and washers, or should they be isolated with tape or plastic washers? If anybody has good gut shot photos of a well shielded rick, I'd really like to see them. I had not realized the pickup wires were shielded, more ignorance! I've read some arcane stuff about adding a "dummy" single coil under the pickguard to add a humbucking function, anybody tried that?

[aceonbass]

I remember reading JH's comments regarding shielding once. I don't know if insulating the wiring from the "Faraday cage" of shielding is necessary or not. When I build a harness, I use two pieces of wire with the insulation split in the middle from the switch around to the neck tone pot. After assembly, I test all the connections with my multi meter. None of my Ricks are shielded, and none of them hum, unless I stand right in front of the amp facing it.

[jps]

...I'm strictly a bedroom hobby player these days, and the wiring in my house must not be well grounded,

If that's the case, you should take care of the house wiring first before you shield the bass.That is most likely a possible safety/code violation issue which should be more important to fix than a bit of 60Hz noise from a bass, perhaps.

[Gilmourisgod]

If that's the case, you should take care of the house wiring first before you shield the bass.That is most likely a possible safety/code violation issue which should be more important to fix than a bit of 60Hz noise from a bass, perhaps.

I don't have the technical expertise to know if the house is properly grounded. The house was built in 1985, so I assume it's up to modern electrical code, but it's wired oddly, outlet groupings oddly circuited, etc. Your basic 80's slap-it-up construction typical of the era on Cape Cod. I do have a lot of dimmers in the house, maybe that's the culprit. My desire to shield the bass stands however, I'm not the first person to have trouble with single coils.

[ram]

florescent lights?

[cjj]

Light dimmers are huge sources of electrical noise. They work by chopping the normally sinusoidal AC wave part way through the cycle to essentially lower the voltage. This chopping creates high frequency components which radiate like hell. Many dimmers never completely stop chopping and so will create noise even when at full brightness.

As for checking proper wiring, go to a hardware store and pick up one of those little 3 light outlet testers:

They are cheap and can tell you if you have problems, which can be a serious safety issue. I've seen a fair number of houses that were wired wrong even though they were done by professionals and signed off by inspectors...

[jps]

We have been v e r y s l o w l y renovating our 1930 house and so far have about half the house up to modern 3 wire grounded circuits (the rest is still knob-and-tube 2 wire). After the first rounds by a supposed commercial electrician i found a few thing done improperly. I would expect a 1985 house to be 3 wire grounded, but do as CJ suggested and get a tester; I keep one in my gig bag and and found lots of bad wiring in venues, indoors and out.

[Gilmourisgod]

I've seen those testers before, you plug into an outlet and it tells you if it's grounded? I'll pick one up. I have one fluorescent fixture in the basement, but it's rarely on, haven't noticed any correlation with bass hum. How about distance to computers? My playing space has a flat screen monitor and PC. I've been tempted to buy a noise gate, but I've read that are a tone suck.

[jps]

I've seen those testers before, you plug into an outlet and it tells you if it's grounded? I'll pick one up.

It also tells you if there are swapped wires and other nasty things. They are cheap and can be a lifesaver, literally.