Post by antigua on Oct 29, 2022 21:49:25 GMT -5
A few months ago I had a lot of pickups from AliExpress, and it was set of humbuckers that had mishmash of nickel silver and brass covers. It's possible to tell them apart with the "network analyzer bode plotter", using the Velleman PCSU 200 and Ken Willmott's integrator, as the brass covers will dampen the resonant Q in a visually obvious way, but to save time I was able to figure out the difference in Q factor at 1kHz for brass versus nickel silver covers, and quickly separate them out using a DE-5000 LCR meter, and it saved tons of time, not to mention than a person might have a DE-5000 on hand, but not all of the bode plotting equipment.
So I wanted to see if the same thing would work with Tele neck pickups, I gave it a try with a couple test pickups and some brass and nickel; silver covers. The results seem promising, with the caveat that the values seem to come different depending on whether the pole pieces of the pickups are "steel slugs" or AlNiCo pole pieces.
This is the I have using two Fender Japan Tele neck pickups, one AlNiCo the other steel with a ceramic magnet, and four covers, two brass and two nickel silver:
Test AlNiCo Pickup
Fender Japan AlNiCo 5 pole pieces
L @100hz: 1.929
C @100khz: 156pF
R: 6.681
Uncovered Q @ 1kHz: 1.728
Q @ 1kHz w/ Nick Silv #1: 1.665
Q @ 1kHz w/ Nick Silv #2: 1.678
Q @ 1kHz w/ Brass #1: 1.448
Q @ 1kHz w/ Brass #2: 1.441
Test Ceramic Pickup
Fender Japan steel pole pieces
L @100hz: 3.335
C @100khz: 157pF
R: 5.981
Uncovered Q @ 1kHz: 2.34
Q @ 1kHz w/ Nick Silv #1: 2.09
Q @ 1kHz w/ Nick Silv #2: 2.12
Q @ 1kHz w/ Brass #1: 1.605
Q @ 1kHz w/ Brass #2: 1.566
The strange thing I that I'm unable to explain is that the pickup with the steel pole pieces has a higher Q factor than the one with AlNiCo pole pieces, but maybe that has to do with the inductance being a lot higher for the pickup with the steel slugs. But aside form that, the nickel silver predictably retains a higher Q factor, while the brass results in a lower Q factor.
A downside I see to this is that if you don't know the Q factor of the pickup in question without a cover, there's no way to measure a percentage in Q factor drop, so it might be necessary to remove the cover, and get the Q factor without the cover, and from there, you could say, if the Q factor dropped by less than 10%, it's likely a nickel silver cover, but if it drops by ~20%, that's more indicative of a brass cover. Removing the cover of Tele neck pickups is a bit hazardous because the bent feet that fold in and hold the cover on and brush against the coil and instantly destroy the pickup if you're not very careful.
Another potentially less destructive way to tell the metal type is to file / sand away the plating on one of the three feet holding the cover onto the pickup, and if the underlying metal is a bluish silver, that would be "nickel silver" where as if it's a yellowish copper color, it's probably brass, but both in both cases I believe they use copper substrate as a catalyst to apply the chrome plate, so you have to file / sand aggressively enough to get past that down to the base metal of the cover.
Here's how they feet appear with the chrome platting grinded away:
The setup:
So I wanted to see if the same thing would work with Tele neck pickups, I gave it a try with a couple test pickups and some brass and nickel; silver covers. The results seem promising, with the caveat that the values seem to come different depending on whether the pole pieces of the pickups are "steel slugs" or AlNiCo pole pieces.
This is the I have using two Fender Japan Tele neck pickups, one AlNiCo the other steel with a ceramic magnet, and four covers, two brass and two nickel silver:
Test AlNiCo Pickup
Fender Japan AlNiCo 5 pole pieces
L @100hz: 1.929
C @100khz: 156pF
R: 6.681
Uncovered Q @ 1kHz: 1.728
Q @ 1kHz w/ Nick Silv #1: 1.665
Q @ 1kHz w/ Nick Silv #2: 1.678
Q @ 1kHz w/ Brass #1: 1.448
Q @ 1kHz w/ Brass #2: 1.441
Test Ceramic Pickup
Fender Japan steel pole pieces
L @100hz: 3.335
C @100khz: 157pF
R: 5.981
Uncovered Q @ 1kHz: 2.34
Q @ 1kHz w/ Nick Silv #1: 2.09
Q @ 1kHz w/ Nick Silv #2: 2.12
Q @ 1kHz w/ Brass #1: 1.605
Q @ 1kHz w/ Brass #2: 1.566
The strange thing I that I'm unable to explain is that the pickup with the steel pole pieces has a higher Q factor than the one with AlNiCo pole pieces, but maybe that has to do with the inductance being a lot higher for the pickup with the steel slugs. But aside form that, the nickel silver predictably retains a higher Q factor, while the brass results in a lower Q factor.
A downside I see to this is that if you don't know the Q factor of the pickup in question without a cover, there's no way to measure a percentage in Q factor drop, so it might be necessary to remove the cover, and get the Q factor without the cover, and from there, you could say, if the Q factor dropped by less than 10%, it's likely a nickel silver cover, but if it drops by ~20%, that's more indicative of a brass cover. Removing the cover of Tele neck pickups is a bit hazardous because the bent feet that fold in and hold the cover on and brush against the coil and instantly destroy the pickup if you're not very careful.
Another potentially less destructive way to tell the metal type is to file / sand away the plating on one of the three feet holding the cover onto the pickup, and if the underlying metal is a bluish silver, that would be "nickel silver" where as if it's a yellowish copper color, it's probably brass, but both in both cases I believe they use copper substrate as a catalyst to apply the chrome plate, so you have to file / sand aggressively enough to get past that down to the base metal of the cover.
Here's how they feet appear with the chrome platting grinded away:
The setup:
