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Humbucker cover vs No Cover

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It depends on the type of cover. The three main types are chromed steel, Nickle and chromed brass.

Brass will have the least effect because its non magnetic. Steel has lower iron content so its not as magnetic as Nickle. Nickle is noted for the best tone because it bends the magnetic fields of the poles.

I justy did another post on this topic so I'll copy and paste it here instead of typing it all over again. .

Brass is non magnetic. The only metals that are magnetic are called feromagnetics and they mainly consist of iron, nickel, cobalt and manganese, and a few other exotic elements. These 4 items can be blended into different combinations, or have non magnetic metals added like alluminum. A popular magnet type is Alnico which contains Alluminum which is non magnetic and Nicle and Cobalt which are magnetic.  

 All brass will do to the magnet field is weaken it slightly. It may add some warmth from the bodies vibration by adding more mass. It will not shape the field in any way. The magnet field passes through brass the same way as it would a piece of paper the same thickness. It will however shield the pickup from stray EMF like AC hum very well.

A body does vibrate and therefore the pickup to a small degree under the strings which adds some sound to the pickup. A pickup with soft foam under it will have more string tone and less body tone than a pickup bolted down hard against the body.

Steel on the other hand contains iron and will change the magnetic field. Instead of having 6 indivudual poles on each string the iron in the steel will bend the fields into one larger field like a blade magnet depending on how much iron is in the steel.

It acts like a "Keeper" Some may know what a keeper is. Its a metal bar that is placed across the poles of a horse shoe magnet to keep it from loosing strength.

Dont know if they teach any of this basic stuff in school any more but you can buy iron filings and lay it out thin on a piece of paper. Then place the pickup under the paper and see the fields with your own eyes. Where the fields project out from a pole, the iron stands straight up. You would see six of these pole ends with an uncoverd pickup. If a steel cover is put on, you'd see less iron standing straight up and more iron connecting between the poles to make it look more like a single pole or blade type pickup. 

Brass looks the same as the uncoverd pickup just a little weaker. What you hear as a result is mostly what you'd get from an weaker uncoverd neck pickup combined with any microphonics the brass adds to the coil pickup up tones from the body itself. 

Nickle is another cover type used on Humbuckers. It has different magnetic permiability than chromed steel does. To many its a key item in vintage tone because its more magnetic than steel and bends the magnetic flux into a blade type pickup. This can have less dropouts bending strings and the two coils and 12 poles will sound more like one large pickup. 

Besides affecting the magnetic field, the cover acts like a faraday cage and keeps magnetic hum from getting into the coils. Humbuckers null this hum due to their opposing winds, but in noisy electrical enviornments, the added shielding can be added protection. They also keep dirt and dust and small bits of iron and nickle that get flaked off guitar strings as they are picked. It may take years for it to be visable but its there none the less.

Pickups that have metal covers should also be potted in wax. Non potted pickups can have the covers act like a microphone diaphram and pickup sound from the room instead of from the strings. These can also feed back like a microphone does when it faces a loud speaker setting up a feedback loop. The wax deadens the covers so they can't vibrate and therefore it quiets them and prevents them from going microphonic.

In general, uncoverd pickups are well portected from physical damage and from getting dirt in them. The bases are pften times different than your coverd pickups so trying to put a cover on them may not work. Also pickup covers may have different hole spacings and hole sizes and are best suited to that kind of pickup to begin with. Adding covers to non coverd pickups is quite pointless. If you do try it go with covers without holes so you dont get burned with pup holes that dont match the pickups poles. Be sure to pot them, if you can get them to solder to the base to begin with. Not all covers fit over the uncoverd pickup bases.


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 What WRGKMC is basically true, but there are definite advantages to brass covers, in that it "softens" the tone for a nice jazzy response by spreading out the magnetic waves. I put a brass cover over the fingerboard p/u on my tele recently, in place of the original nickel-silver one it came with, and really like the change a lot, so have ordered one for the fingerboard p/u on my 'bucker equipted SG Special, to see how it will sound.


Covers are fairly inexpensive, so try different ones, and see what tickles your ear!


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  • 6 years later...
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That's 99% bad information-basically misinformed imagination ;-)   

-no such thing as "steel" humbucker covers

-brass , (or any conductive metal) definitely affects the magnetic field-and sound of guitar pickups. (Pickups are high-Impedance AC devices, not DC.) that you don't understand that fact, or it's implications, is the basis of most of the misinformation posted above..

-in short: so-called nickel-silver covers exaggerate treble and cut bass, while brass covers roll-off treble.  (and "chrome-plated steel" covers don't exist.)

the sonic effects are more clearly shown on a single coil pickup: -try changing a brass tele cover for a " transparent" nickel-silver cover, and you'll find exactly the differences i describe above. ;-)   the traditional brass tele cover creates the traditional dark/dull treble,  the newer nickel silver covers create  hyper-treble with no bass. 

these  same effects are reduced  in humbuckers because the two opposite-wound coils interact, with each coil's eddy-current  losses adding to the other coil's output> diminishing the overall effect of the cover.

-the only 'transparent' covers are non-conductive (magnetically or electrically). I.E.  plastic covers, etc

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