Pickup pole piece shielding

[eutgard]

I've found a article about pole piece shielding at Audere Audio site.

http://www.audereaudio.com/FAQ_PUMag_Gnd.htm is the link.


I've also found out that 'modern' line bass pickups of Nordstrand have pole piece shielding on them.

http://www.nordstrandpickups.com/bas...rn/modern.html

But someone around me tried this method by himself previously and experienced severe degradation of tone and output volume.

Now he claims that this pole piece shielding is band aid solution to serious underlying problem and should not be tried.

What could be gone wrong shielding pole pieces?

[Searcy]

Originally Posted by eutgard

I've found a article about pole piece shielding at Audere Audio site.

http://www.audereaudio.com/FAQ_PUMag_Gnd.htm is the link.


I've also found out that 'modern' line bass pickups of Nordstrand have pole piece shielding on them.

http://www.nordstrandpickups.com/bas...rn/modern.html

But someone around me tried this method by himself previously and experienced severe degradation of tone and output volume.

Now he claims that this pole piece shielding is band aid solution to serious underlying problem and should not be tried.

What could be gone wrong shielding pole pieces?

Your friends bass has a coil that is shorted out against the magnets. It's very common on Fender pickups because they don't insulate the magnets. Your friend is wrong and is generalizing from the specific. It don't work dat ways.

[Audere]

So Fender does not use any insulating tape?
Thanks for the info...

When do/did they use a plastic bobbin on a jazz pickup?

[DavidRavenMoon]

Originally Posted by Audere

So Fender does not use any insulating tape?
Thanks for the info...

Nope. It's very common for the coil to get shorted out on the magnets too. This is probably why Fender never grounded their magnets.

Crazy, huh?

I have a 5 string Jazz Bass pickups here with steel poles and ceramic magnets that's made with the fiber flatwork. Peering through one of the small holes with a loupe and a flashlight, I can see what looks like the back of black paper tape. So it seems they might tape some pickups, but traditionally they didn't.

Originally Posted by Audere

When do/did they use a plastic bobbin on a jazz pickup?

Some of the newer pickups use plastic bobbins, which of course insulate the coil from the magnets. But it also places a space between the coil and the magnets, and the pickups don't sound the same either!

The plastic bobbins are easier to make, so it's only a cost cutting measure on Fender's part. Instead of assembling the pickup from a top and bottom flat, help together by the magnets, they just push the magnets, or often steel rods, through the molded holes. For the steel pole pickups they use two ceramic magnets on the bottom.

[DavidRavenMoon]

Originally Posted by eutgard

But someone around me tried this method by himself previously and experienced severe degradation of tone and output volume.

Now he claims that this pole piece shielding is band aid solution to serious underlying problem and should not be tried.

What could be gone wrong shielding pole pieces?

If you have a metal part in a pickup, it should be grounded.

As Clint mentioned, likely he experienced a short between the coil and magnet.

Another thing that can cause a degradation of tone is when you shield your pickups with copper foil, and you wrap a piece of foil completely around the coil. This creates a closed loop around the coil, and that will usually cause a loss in high end. You should always either leave a gap in the shield so the two ends don't touch, or insulate the ends with electrical tape.

[DavidRavenMoon]

And people took me to task for saying Fender's standard pickups are not very good!

[#include <MK>]

Originally Posted by DavidRavenMoon

And people took me to task for saying Fender's standard pickups are not very good!

lol, that's it. I think we laid it out plain and crystal clear but still got flack. No problem there, it had to be said.

[eutgard]

BIG thanks for all the valuable advice!

Now I can see it clearly

[DavidRavenMoon]

Originally Posted by #include <MK>

lol, that's it. I think we laid it out plain and crystal clear but still got flack. No problem there, it had to be said.

I swear, sometimes I wonder why I bother! I just read these things and think "wait a minute.. that's not right!" and really just want to do a service by giving what I believe to be valid info.

But people are happier to live in their own world.

[eutgard]

Originally Posted by eutgard

I've found a article about pole piece shielding at Audere Audio site.

http://www.audereaudio.com/FAQ_PUMag_Gnd.htm is the link.


I've also found out that 'modern' line bass pickups of Nordstrand have pole piece shielding on them.

http://www.nordstrandpickups.com/bas...rn/modern.html

But someone around me tried this method by himself previously and experienced severe degradation of tone and output volume.

Now he claims that this pole piece shielding is band aid solution to serious underlying problem and should not be tried.

What could be gone wrong shielding pole pieces?

After I said to him the worsening of tone/output is due to the magnet/coil short, he said already mentioned 'underlying' problem is actually short of magnet/coil.

So, if there is no short of magnet/coil, there will be no noise when touching pole pieces and if there is already short, pole piece shielding will worsen the problem... he said.

I'm confused now...

[DavidRavenMoon]

Originally Posted by eutgard

So, if there is no short of magnet/coil, there will be no noise when touching pole pieces and if there is already short, pole piece shielding will worsen the problem... he said.

No, that's incorrect. If there is NO short, and there shouldn't be a short, and the magnets/poles are not grounded, you will get noise if you touch them.

David Meadows correctly and clearly explains why on his web site. If your friend knows more than David, I'd like to hear his explanation!

This is also why if your strings are not grounded, you get noise. Metal parts act as an antenna. Grounding the metal parts shunts that noise to ground.

If your magnets are shorted to the coil... well you have a problem. And that has nothing to do with grounding the magnets. grounding the magnets just makes the problem show up. Even without grounding the magnets, an internal short in a pickup can cause issues with the tone.

I tape off my poles before I wind, and the poles are indeed grounded.

I get no noise, and no degradation of tone either.

Originally Posted by eutgard

I'm confused now...

Your friend is the confused one!

[eutgard]

He says pole piece is signal part, so if it is grounded there will be loss of signal...

Hmmm...

At http://www.audereaudio.com/FAQ_PUMag_Gnd.htm David says 'When pickups are wound with the magnetic wire directly against the magnets or pole pieces, i.e. no thick bobbin, then there will be strong capacitance coupling in between the magnetic parts and the wire'

So if there is no actual contact between coil and pole pieces, will there be some kind of 'coupling' between the two?

[DavidRavenMoon]

Originally Posted by eutgard

He says pole piece is signal part, so if it is grounded there will be loss of signal...

Hmmm...

At http://www.audereaudio.com/FAQ_PUMag_Gnd.htm David says 'When pickups are wound with the magnetic wire directly against the magnets or pole pieces, i.e. no thick bobbin, then there will be strong capacitance coupling in between the magnetic parts and the wire'

So if there is no actual contact between coil and pole pieces, will there be some kind of 'coupling' between the two?

Some makers use the inside of the coil as hot, and some use the inside as ground. If you make a humbucker and wind both coils in the same direction, which is very common, you get one coil done both ways.

The amount of capacitance is very low and is probably swamped by the cable capacitance anyway. Also shielding the pickups with foil will raise the capacitance. You don't hear the change in most situations.

Also that coupling gives the pickup its tone. I make pickups with blade poles, and I prefer to wind right on the insulated blade. I think it sounds better.

From my own experience winding pickups, If I disconnect the ground to my poles, the only difference is added noise.

I'd wager if your friend was to sit and listen to pickups done both ways, he wouldn't be able to tell the difference.

Some people worry needlessly about small details.

[Searcy]

Tell our friend to check his pickups like this and see if they are shorted to the poles.

http://sixstringbliss.proboards67.co...ead=1180126762

Better to know what's going on than assume.

Ohhh and like Dave said. Don't worry too much about it. The groove is what matters.