Re: Covers or no?

Tony Done wrote on 29/12/2008 :
On Dec 29, 6:40 am, Arlowe <bare.ar...@xxxxxxxxx> wrote:
DeeAa presented the following explanation :





On 28 joulu, 08:36, devon.dej...@xxxxxxxxx wrote:
Humbuckers here. A lot of people tell me there's a difference in sound
between buckers with covers and not. But I've never been in a position
to be able to test the theory out.

Anyone?

I've never removed Gibson PU covers and tested, but I've *added*
chrome covers to pickups thinking it'd look cool.
That did change the sound some; it turned a little darker, or less
raw. I tested a few different ones, and not surprisingly, with a cover
that also covered the pole pieces, the sound was very clearly quite
different. A dead herring would have detected the difference, it
simply killed all highs and clarity. But covers that left them pole
pieces  visible...very small difference in comparison. But definitely
some.

It also led me to experiment with pickups and adding various bits of
metal on, around and under 'em and yeah, basically anything does
change the sound a little but the biggest difference by far comes when
you add metal on (and touching) the pole pieces.
I might actually have some sound clips of my tests, I'll try and look
for them.

Cheers,

Dee

If your pickup cover is made from a material with a high magnetic
permeability  (nickel,stainless steel or ferrite)there would be a
difference.

The higher the permeability the less magnetic field for the strings to
break, thus less effect the strings will have on the field.
 The aluminum covers they use on pickups have a very low magnetic
permeability so they have no more of an effect the field than air does.

If the covers you tried were not pure aluminum then it is possible that
they were effecting the field.

It could also be caused by the chrome plating on some covers...if the
plating has a high nickel content then it could be having a shielding
effect.- Hide quoted text -

- Show quoted text -

Who makes aluminium covers? All the metal ones I've seen have been
german silver, chrome plated brass or nickel-plated brass. You might
expect anything with nickel plating to have a marked effect because it
is ferromagnetic (chrome isn't). However, other electrically
conductive materials would be expected to have some effect, at least
in theory, due to induction effects. Whether you can hear it is, of
course, another matter.

Tony D

The only pair I have ever removed were anodized aluminum, but it doesn't matter.
Silver, aluminum, platinum, manganese, copper, zinc, gold and chromium all have a relative permeability of roughly one or less so they will have no effect on the field.

I don't understand how electrical induction could have anything to do with the cover...electrically it should be at ground potential and can not effect the voltage or current flow in the coils. In fact, this should offer ideal shielding from EMF and prevent noise from entering the circuit through the coils.


.

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