Shielding Pickups

[ShortBuSX]

Hello, Im a newb! Ive been searching high and low about shielding pickups...but there isnt much reference, Ive read like 3 decent write ups(best one by Torres).

I also keep reading reference to SRV's "number one" having shielded pups...but thats it, no pics and no description of how or why. *shrug*

So thats why Im here....hoping someone could elighten me.

[Spence]

Contact AllParts for self-adhesive copper foil. You wrap it around the pickup coil and solder to earth.

That, alledgedly is what the SRV pickups were like.

[ShortBuSX]

Yeah, Ive already got the copper tape and have shielded the rest of the guitar...I guess Im just looking for some dirrection, something to copy, something to embelish upon...or even some reasons not to do it.

[David King]

Check out these two pages on the audereaudio site:
http://www.audereaudio.com/FAQ_PUNoise.htm
http://www.audereaudio.com/FAQ_PUMag_Gnd.htm

Not many pickup winders bother to shield since neither leo nor seth thought it was important.

[Joe Gwinn]

Yeah, Ive already got the copper tape and have shielded the rest of the guitar...I guess Im just looking for some dirrection, something to copy, something to embelish upon...or even some reasons not to do it.

Copper tape works OK, so long as you avoid making a shorted turn, so don't allow the tape to adhere to itself. Put some insulating tape in between.

[Ruel]

Look up guitarnuts.com. There is a section devoted to guitar shielding.

[ShortBuSX]

Copper tape works OK, so long as you avoid making a shorted turn, so don't allow the tape to adhere to itself. Put some insulating tape in between.

See, I was considering something(almost identical) like this(from the first link):


But if I understand you right, then his corners(on his pup covers) shouldnt touch? Or in my case(rounded strat covers) I shouldnt complete the circle/wind? But instead leave a gap or use something like electricl tape to keep the ends from touching?

Also, in the second link they say:

Ground the Magnets or Pole Pieces. The best way to ground the parts is to apply conductive copper foil with conductive adhesive against the bottom of the pickups and run a new wire to ground. Note: this ground wire must be connected to the output jack or cavity ground and not to the pickup common.

This kinda confuses me because I immeditaely think of Tele bridge pickups or others with metal baseplates...and they use the common on the pup Unless Im confused in what a baseplate and a sheild does.

The other example Ive got/seen contradicts all the above


And the lastly, the first link says:

Does this change the tone of the pickup?

Yes, slightly in High Z-Mode. If you look at the top illustration you will see the pickups are now capacitively coupled to the ground. A very complete shielding job, as shown above, will add approximately 90 pF of additional capacitance to the pickups. This additional capacitance will slightly lower the frequency of the response peak in the High Z-Mode. This capacitance can be compensated out by 95+% of our customers, if desired, but it is rare because most people choose a High Z-Mode C loading larger than this. The pickup's tone in the other Z-Modes will not be changed.

What is "High Z-Mode"...Im not familiar with this reference?

This whole pickup shielding is confusing...one source says "ideally youd want to shield pickups", another says "dont bother", and another says "itll affect tone" and the other says "just a little bit"...there is very little reference about shielding pups, the most common reference is to the only guy with shielded pups whos not lacking tone(SRV) and there arent any examples of what or how his were done...and now someone suggests this is only rumour

[Possum]

SRV

I have studied everything I could get my hands on about SRV's pickups in his number one guitar. Fender did an "autopsy" of his guitar in a hotel room in Austin and they did mention shielded bobbins. Probably just copper tape around them, what else could it be, the guys working for him weren't high tech geeks and copper tape shielding was known at the time.

[David King]

What is "High Z-Mode"...Im not familiar with this reference?

"High Z mode" is unique to the Audereaudio bass preamps. You can change the input impedance loading of the buffers from low to mid to high. What he's saying is that you won't hear a difference with the magnets grounded on a bass unless your input impedance loading is above 1 Megohm. I wouldn't sweat it.

The other example you showed (BTW when you rip other people's photos off the web it's nice to attribute them) where they are grounding to the pickup's common is WRONG but everyone has done it that way that since the beginning of time so who are WE to argue? It's like pitting science against the Bible, the Bible wins every time.

[Spence]

Why go to all this trouble?

Why not just slip a tiny humbucking choke in the circuit? Make it low enough in DCR to avoid any over bearing effect on the pickup tone.

[David Schwab]

Check out these two pages on the audereaudio site:
http://www.audereaudio.com/FAQ_PUNoise.htm
http://www.audereaudio.com/FAQ_PUMag_Gnd.htm

Not many pickup winders bother to shield since neither leo nor seth thought it was important.

And ground those magnets! Every metal part on a pickup should be grounded.

[David Schwab]

What is "High Z-Mode"...Im not familiar with this reference?

I'll add further to David's explanation. If you buffer high impedance (Z) pickups, you get a very different tone than when they were passive. This is because they are seeing a very hi-z load, and basically aren't being loaded at all. The load usually sets the point where the high frequency roll off starts, and you get a resonant peak at that frequancy. When you buffer the pickup you get a lot more high end, and the resonant peak is shifted higher.

Some people might not like that change in tone. So if you load the pickup at the input of the preamp with a lower Z, you simulate the tone of the passive pickup going to the "normal" loads of the controls, etc.

The Audere preamp uses a combination of caps and resistance to simulate a lower Z load on the pickups. So you can get a "modern" crisp tone, or a fat "vintage" tone.

I've been doing something similar with my pickups. EMG do something similar as well that they call "tone modeling".

[David Schwab]

This kinda confuses me because I immeditaely think of Tele bridge pickups or others with metal baseplates...and they use the common on the pup Unless Im confused in what a baseplate and a sheild does.

That doesn't mean it was the right way to do things. The reason the Tele has a large metal bridge with the pickup attached, and metal control plate, is because in the early days of electric guitars, they felt the electronics had to be mounted on metal. You see this on other early electrics... metal pickguards and stuff like that. Look at the early Jazzmasters. Aluminum pick guards and brass lined cavities. Obviously Fender was concerned with noise, especially after Gibson came out with the humbucker. Lack of noise was a selling point back then. Gibson felt it was important enough to come up with a new pickup design, even though the P-90's sounded great.

The other thing with the Tele is the base plate is magnetic, and changes the tone of the pickup. This may or may not have been intentional.

You really should run your shields separately from your pickup common if you can. Keep in mind that Fender didn't even use shielded cable. But these days when you see 4 conductor cable, they either have a separate ground wire, or you use the braided shield to connect to the pickup shielding.

In the photo of the pickup with the copper foil around them, you'll see what Joe Gwinn was talking about. They have the foil wrapped around the coil, which could affect the tone because it acts as a single turn coil. It's better to not have both ends of that foil wrap touch each other.

The foil in the covers/cavities aren't shaped like a single turn conductor.

Obviously there are a lot of pickups/guitars with no shielding at all, or old vintage style wiring. None of this stuff will stop a pickup from working. But if you are trying to get rid of some noise these are things to try.

I would take everything posted on Guitarnuts with a big grain of salt. Most of the stuff I've read there is quite nonsensical. Like the wire loop on your finger connected to the string ground!

[GlennW]

This was wrapped around the coil on a Hagstrom HIIB bass pickup. The little solder blob is where it was attached to the baseplate. Those guys were the shielding kings, especially for the '60s. They foiled the body routes and had aluminum for the bottom layer on pickguards.