Pearly gates, cover vs no cover
- Thread starter gimmieinfo
- Start date
freefrog
Well-known member
That's because you've never pulled off a bad cover.
Stock humbuckers of an Ibanez AS73 are an example of that: covered, they are muddy. Uncovered, they become different pickups, much clearer. Same thing for some Epiphone transducers.
As shown in the pics that I've shared above, it can make differences of 3 to 12dB, depending on the frequencies involved. That's more than one would obtain from 250k vs 500k pots. It would be impossible not to hear it (except through a Boss Metal Zone of course). ;-)
Stock, Duncan products are obviously not fitted with this kind of bad covers. But the quality of aftermarket ones is rather random and doesn't always depend on their price... IME. YMMV.
That's because you've never pulled off a bad cover.
Stock humbuckers of an Ibanez AS73 are an example of that: covered, they are muddy. Uncovered, they become different pickups, much clearer. Same thing for some Epiphone transducers.
As shown in the pics that I've shared above, it can make differences of 3 to 12dB, depending on the frequencies involved. That's more than one would obtain from 250k vs 500k pots. It would be impossible not to hear it (except through a Boss Metal Zone of course). ;-)
Stock, Duncan products are obviously not fitted with this kind of bad covers. But the quality of aftermarket ones is rather random and doesn't always depend on their price... IME. YMMV.
That's probably true. I never needed to take off a cover of a pickup I didn't like. I just got a new pickup.
Artie
Peaveyologist
Hey freefrog; Do you think these covers would be decent quality, to put over a "Duncan Designed" JB/Jazz set? (I'll airbrush them my desired color.)
https://mojotone.com/products/humbu...8&_fid=70019108b&_ss=c?variant=41689603997792
freefrog
Well-known member
Hey Artie,
The text mentions they "are not made out of brass like most covers". And their bare finish excludes the thin buffering coat of copper often present under nickel plating... So these covers should be magnetically transparent, at first glance.
(As long as you don't airbrush them heavily with pigments containing magnetic materials, I suppose... I measured eddy currents once through plastic covers that I had sprayed with grey paint).
Side note: dipping in vinegar covers with copper under plating is a good way to give them a bicolor steampunk look...
marcello252
Well-known member
this
marcello252
Well-known member
STR-1 tele rhythm, day and night
Artie
Peaveyologist
Thanks. I'll be cognizant of that when I choose a color. Some of the "metallic" colors I looked at do contain metal particles.
Not my favorite pickup, so I'd respect your experience.
gimmieinfo
New member
Heres a question. This is purely out of curiosity, i already decided not to try removing them from the replies. But this thought hit me and i'm just curious. I think i know the answer, but the question is if you isolate the cover from ground, which you COULD do with tape and not soldering it not in the case of a tele pickup not soldering the tab, would that cause any difference a cover usually makes from happening?
freefrog
Well-known member
The cover would still touch the screw poles, passing through the keeper bar, itself in contact with the grounded baseplate... and mainly, it would still form a closed loop around the pickup, causing Foucault currents.
There's a way to diminish these eddy currents from covers but it's cosmetically "discussible": https://kenwillmott.com/blog/archives/246
Now, your idea of tape is still interesting IMHO : separating a magnet from the baseplate with tape has effectively a subtle effect IME. It's a first step toward lamination, as used in transformer cores to minimize eddy currents...
gimmieinfo
New member
The cover would still touch the screw poles, passing through the keeper bar, itself in contact with the grounded baseplate... and mainly, it would still form a closed loop around the pickup, causing Foucault currents.
There's a way to diminish these eddy currents from covers but it's cosmetically "discussible": https://kenwillmott.com/blog/archives/246
Now, your idea of tape is still interesting IMHO : separating a magnet from the baseplate with tape has effectively a subtle effect IME. It's a first step toward lamination, as used in transformer cores to minimize eddy currents...
Well, i can see how it can easily be done. For one, the slugs just need tape over them and the screws can be adjusted a bit lower so as not to touch the cover and IMO that doesn't really affect the tone. But that aside, the point was assuming you can, would that change the effect a cover normally has. Does it HAVE to be grounded to cause the change a cover normally causes? If the only reason is the cover affecting the magnetic field i would think it would do that grounded or not. On the other hand, i find shielded guitars lose highs but if i detach any wire and cover any points that ground the shielded cavity i find it no longer dulls the highs. So maybe a cover thats not contacting ground would have no effect.
freefrog
Well-known member
Sorry to repeat myself (and Ken Wilmott) but: Eddy currents are there as soon as the cover forms a closed loop around the coils, grounded or not.
Even a simple ring around them does that (as confirmed by tests with our own lab gear). You could saw the whole top of a cover, keep it shaped as a ring like around a DynaSonic single coil, and it would still generate eddy currents.
But once this loop open, thx to some vertical slot(s) in the ring, eddy currents are no more there or become subtle enough to be indetectable.
To me, your finding about shielding loosing high has to do with parasitic capacitance, and not with eddy currents.
Now, Foucault currents are not necessarily bad: in the "case" of a Dynasonic, for instance, they contribute to make the tone smoother and more open. So, many pickups are actually designed to promote a reasonable amount of eddy currents (like most DiMarzio's). But as a matter of fact, this factor limits the amplitude of resonant peaks + transients and makes attack slower (a cover on a pickup works somehow like a very subtle compressor always on, wether players hear it or not).
marcello252
Well-known member
I don't pretend to put a definitive sentence but I'm quite sure about the STR-1, with the cover on it's pretty dark on my teles, especially if you use brass bridge, when you take the cover off it gets clearer, I do like it much more that way
KNUCKLHEAD
New member
Marcello , do U have a Brass nut on that Tele ? if not that's another way to counter that Neck pickup ( of course There Aren't many Ax's I Dont like a brass nut on
marcello252
Well-known member
No, I have bone at the moment. I had a brass nut once in a strat and I actually didn't like it at all
