Pickguard Shielding
- Thread starter Lazarus1140
- Start date
uOpt
Something Cool
Eddy currents are why humbuckers with covers sound a little different. Same concept as getting shielding too close to a Strat pickup.
GuitarStv
Sock Market Trader
A faraday cage is what you're building when you shield a guitar pickup cavity - that's why the shielding should help reduce noise.
Effect of the closed conductive loop around your pickup. Measured.
beaubrummels
Well-known member
Except it doesn't show what the coils measured without it.
White line is the closest one, where the loop effect is minimal.
Not exactly the same since a metal pup cover covers/surrounds the entire pup. The pickguard shielding on a Strat doesn't cover the pup.
The cover on a humbucker pup interferes with the wave transmission from the string to the pup magnet/coil by allowing some of the wave energy to be picked up by the cover and to go to ground through the baseplate. That effect doesn't happen in a shielded Strat. I admit that I'm not an electrical engineer so I could be way off base here, but I don't think that's the same thing.
The practical/real world effect on the tone of the guitar with shielding is minimal enough to exclude any theoretical/calculated values. I'm not saying that eddy currents don't exist nor that faraday cages can't be designed to block certain frequencies/wave lengths getting to or from a pickup, just that we don't really need to worry about it in regards to playing guitar in the world that I live in.
Hey, we're just guitar players in a world of performing for fun and money. When we are performing,. any electrical interference/static is amplified and can be very annoying. I just want to make guitars that keep it to as minimal as possible. I've never heard any negative affect on my tone in any of my 5-6 dozen guitars in that setting...and most of those have P-90's or other single coils.
Chistopher
malapterurus electricus tonewood instigator
Man, y'all are a bunch of nerds. If it bothers you that much, buy a noise gate and get back to practicing. You're never gonna win Battle of The Bands and the heart of that alt girl you've been talking to if you spend all your time on the internet debating electricity. If you can't tell me how to go from the time to the frequency domain, or what Ke represents, you do not need to be telling me about eddy current.
uOpt
Something Cool
For the amount of eddy currents you generate (and hence the effect on the amplitude of the resonance peak of the pickup) that doesn't matter. All that matters is how much conductor is in the oscillating magnetic field at which field strength.
That is also why a standard Telecaster bridge has a strong influence although it is not between pickup and strings.
Are you saying that the telecaster bridge diminishes the high frequencies the same way a humbucker cover between the pup and strings does?
uOpt
Something Cool
It does, although probably less so since there is less conductive material toward the center of the magnetic field.
And it isn't some kind of random treble rolloff. It reduces the amplitude of the resonance peak. Very specific.
beaubrummels
Well-known member
Where's the test that measures having a gap in the loop showing it does nothing compared to a coil with no loop in the first place?
Sorry, I couldn't screenshot the whole article.
https://kenwillmott.com/blog/wp-content/uploads/2016/11/Pickup_Cover_Geometry.pdf
ErikH
Well-known member
I used Reynolds heavy duty aluminum foil to shield a Strat pickguard and the cavity some years ago. It worked great.
beaubrummels
Well-known member
We're making a leap from the covers to what affect shielding has without any real testing to verify. The strongest and most significant magnetic fields and interference effects are pretty close to the top of the coil, so covers would have a greater effect, but shielding is a different geometry, nowhere near as thick as those wires nor the thickness of a pickup cover, further from the top of the coils, and if you cut it, it loses some of it's noise rejection properties. The article noted that those wires were thicker and more conductive than covers and the losses were about half with an actual cover; the losses showing were already in the 3-6db range with the wire, which is the smallest increment the human ear can detect as a difference. If you take a reading with 14 ga wire, then divide for shielding that is on the order of fractions of a millimeter, I would expect the effects to be minimal; I'd certainly question whether they would be audible given the results of the article. The article doesn't discuss what happens to noise rejection when introducing a gap, which is the purpose of a cover and shielding.
Am I reading this right - "3-6 dB range is the smallest increment the human ear can detect as a difference"?
Can I see the tests?
beaubrummels
Well-known member
6dB is twice the difference in the voltage. Twice. If it is the smallest increment that you can hear - well, I can understand why there is no difference for you (no offence meant)
Just noticeable difference for the majority of humans is 1dB. Well trained ears in the studio can notice even smaller, up to 0.3-0.5dB, but it depends on the acoustics and sound material, so it is a rare scenario.
Sigh. About a half of your pickup coil is exposed over the shielded stratocaster pickguard. As uOpt stated, you need to shield your wires, not the pickup itself.
Faraday cage model is relevant for the EMG pickups, that are fully covered in the conductive plastic, not for the classic stratocaster singlecoil.
So. Can I see the tests? Because my practical experience tells me that there is no difference in the noise because of 3 narrow cuts.
Chistopher
malapterurus electricus tonewood instigator
6dB in voltage is not 6dB in volume.
Chistopher
malapterurus electricus tonewood instigator
Also that 0.5 dB figure is based upon determining the volume difference of a single tone in a controlled environment. Asking if a single tone is louder, quieter, or the same volume from the one played immediately before it in a quiet room is different from asking if a given frequency in a complex non-constant signal is louder, quieter, or the same volume than it was a half an hour ago before you shielded the pickup.
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