Shielding pickups

[stratovani]

I just recently got a hold of some 1/4" copper tape, and I'd like to try shielding the pickups on my Strat. All the inner cavities are already shielded, but there's always a bit of residual hum in the background, and I'd like to try shielding the pickups as a last resort. Anyone know how to do this? Do I just shield the windings or do I encase the entire pickup with the copper tape, and punch holes for the pole pieces?

[sumgai]

stratovani,

I would not recommend this, but since you asked so nicely......

A pickup is susceptible to electromagnetic hum from all directions, so yes, the more material you cover, the better. But be aware that I've done some comparison testing, and without a set of measurements other than what my ears told me, I can say that shielding the pickups at all will only reduce the background hum an additional 2 or 3 percent..... at the best. But as the weasels lawyers like to say, YMMV.

What you most want to do is make d@mn sure that you insulate the coil wires from possible contact with the shielding tape. Standard electrician's black tape would work here, if you've already got some. The one thing you don't want to do is rely on the shielding tape's stickiness to hold it against the inside of the pickup cover..... eventually that stickiness will become null and void, and at that point, the shielding material may fall against the coil(s). If that happens, your sound will be in for a world of hurt. Talk about Tone Suck!

HTH


sumgai

[UnklMickey]

interesting question.

personally, i think that shielding a pickup in an overzealous manner could have an undesireable affect on tone.

as luck would have it, John Atchley has a "coming soon" section on shielding pickups.

this link:



is contained within the QTB instructions. followed by this:

it doesn't go anywhere.................YET.

but i'm sure it will be an interesting read, when it is in place.



unk

[ccoleman]

yeah u dont want to 'sheild' the pickups from the moving strings in their normal course of disturbing the pickup's electromagnetic field in the desirable way that we want them to...

[sumgai]

Well, we have covered this topic before.

Indeed, one can over-shield a pickup, thereby preventing some of the string's vibrations from being, well.... picked up. Which is another good reason not to do this mod unless all else has totally failed to cancel objectionable hum.

I've got two flourescent lights in my work area, a dimmer on the few remaining incandescent lights, and both legs of the main supply running to different parts of my work room. If that isn't a case for introducing hum, I don't know what is. The before and after "pictures" of doing a QtB to any guitar is amazing. (Hmmmm, perhaps I should keep an un-Quieted beast on hand for demo purposes. Memo to self: Make more money by showing what a shielded guitar can do.) The one time I enclosed the pups (inside the covers, up to the top of the bobbin, but not over it), there was possibly a very tiny difference. But that may have just been wishful thinking, it was so small a difference.

And you know what? It just now occurred to me that there is a better way to test this scenario for effect - shield just the pups first, then do the QtB operation! Wow, what a concept!! Maybe later this year, if I get another shielding job on something that isn't a pile of balsa wood to start with.



sumgai

[ccoleman]

sumgai....... Can you post MP3's of the unshielded and shielded single coils then add the QTB mod and post an MP3 of that too ??!!??

[sumgai]

cc,

Be happy to, once I get a guitar repair job in the door.

A Post-It note has been stuck to the lid of the toolbox! ;D


sumgai

[mikesr1963]

When the Fender guys pulled SRV's number one apart, to measure the exact copy, the only shielding was wrapped around his pickups.

[sumgai]

mike,

When the Fender guys pulled SRV's number one apart, to measure the exact copy, the only shielding was wrapped around his pickups.

Yes, we've heard that one before, but thanks.

If the story is true, then what it shows is that:

a) Stevie's tech(s) didn't know the full story about shielding, or;

b) They were lazy about the job, or;

c) Stevie didn't care, he was satisfied with what he heard/didn't hear (according to his ears).

It's a fact that while the pickup coils do indeed receive the majority of objectionable hum, they account for no more than 75 or 80% of all the hum coming out of a guitar. The fastest way to demonstrate that fact is to simply disconnect one coil of an HB, observe the total hum in the system, then hook that coil back up. Now how much hum is there? It's not all gone, is it. (Rhetorical question, I know there is still some hum present.) That's why the vast majority of the GuitarNuts here have performed JohnA's "Quieting the Beast" operation, whether they be single coil lovers or HB Nuts! ;D


sumgai

[vonFrenchie]

Noiseless pickups.... there isnt any false advertising that is less true than this. No pickup is noiseles. humbuckers arent noiseless. I can hear the noise in my guitar, but its quiet. The best you can do is avoid things that have an electromagnetic field (i hope im right). This will GREATLY reduce hum. If I'm two feet away from my computer my humbuckers arent humbucking. If I'm outside... my humbuckers are well... humbucking.

Id say cover only the part of the pickup that is under the pickguard and make sure that it is connected to the cavity shield.