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Wiring: Shielded needed or not?

Discussion in 'Tele-Technical' started by NoTeleBob, Oct 11, 2020.

  1. NoTeleBob

    NoTeleBob Tele-Meister

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    Seems like modern pickups are always shielded wire... but I still see controls wired with plain or twisted pair.

    Does shielded matter? Does it help cut single-coil hum? How good is twisted pair at doing the same?
     
  2. TeleTucson

    TeleTucson Tele-Afflicted

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    Shielding wire and twisted pairs are good practice, but if you've got single coils your hum will overwhelmingly be due to the pickup itself. So, IMO shielded wire is not necessary for single coils.
     
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  3. wabashslim

    wabashslim Tele-Afflicted

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    Not to mention the hassle of wiring up shields on 1 or 2 inch wires - & caps!
     
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  4. 2manyteles

    2manyteles TDPRI Member Silver Supporter

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    Shielding cavities is good practice- like shielding wire or twisting pairs. It will reduce that buzz that you notice when you take hands off the guitar. If done really well there's almost no buzz. Don't confuse buzz with hum though. Can't do anything about the hum.
     
  5. stormin1155

    stormin1155 Tele-Holic

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    There are two types of unwanted noise that your guitar can produce, especially single coil pickups: 60 cycle hum and RF noise. Humbucker pickups were developed to combat the former; shielding can help reduce RF noise. RF noise comes from any number of electrical devices... florescent lights, computers, electric motors, etc. For shielding to be effective it needs to be grounded.
     
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  6. NoTeleBob

    NoTeleBob Tele-Meister

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    So twisted pair is as good as shielding in for cavity wiring?

    If I do the aluminum tape thing along in the cavity along with the faceplate w/ground screws, is that as good or better than worrying about shielded wire?
     
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  7. TimTam

    TimTam Tele-Holic

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    The exact results will vary by pickups, wire lengths, EMR environments, etc. But enough people have tried cavity/pickguard grounded shielding and found reduced noise for it to be the recommended approach. Maybe a few electrical engineers have actually measured the noise floor before and after. If so, it would be nice if they would publish their results. Maybe engineers have also compared paint to copper foil to aluminium foil to brass plates, for a range of noise sources. But like many aspects of guitar electronics, optimum noise shielding seems to have mostly escaped the scrutiny of objective analysis using the techniques of modern electronic engineering. Which is why many aspects of guitar wiring haven't changed much since the 1950s, while the rest of electronics has moved on. Whether standard electronics practices like twisted pairs or shielded conductors offer much above the level of noise protection from paint/foil is uncertain. If you look just at Fender, much of the MIJ range uses shielded conductors, as do some Squiers (which are made in a range of countries/factories). But MIA is predominantly unshielded conductors. OTOH many modern Fenders across various factories tend to use cavity shielding paint (or shielding plates in some vintage reissues). Does Fender USA have evidence that paint shielding is sufficient ? Does Fender Japan have evidence that it's not ? Twisted pairs and shielded conductors are both easy to do. So in the absence of direct evidence for their efficacy in this particular application, one might still say "why not use them ?". Of course Gibson's use of shielded conductor pickup wire still earns them an overall fail because they mostly forget to insulate the stuff !
     
  8. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Try it and see! It won't cause any harm. Let us know the results.

    I use twisted pairs and/or shielded wire in tunnels - like to the output jack. But keep in mind, shielded wires and twisted wires won't shield the pickups. If you are out to eliminate all noise, I recommend adhesive copper tape in all cavities and where necessary on the pickguard - properly grounded of course.
     
  9. brookdalebill

    brookdalebill Tele Axpert Ad Free Member

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    Shielding has negligible results, IMO.
    If hum “bugs” you, hum cancelling pickups are the only real solution, again, just my opinion.
    All of my electric guitars, except my gold top have hum cancelling pickups.
    None are shielded.
     
  10. loopfinding

    loopfinding Tele-Holic

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    i think the shielded paint is just a factor of being easier and cheaper in the long run to apply. most of the guitars that i've measured the resistance to ground from the paint, it can be high enough of a resistance not to beep out on a meter's continuity setting. i would think shielded runs on top of this would be negligible, i also guess it would upset some people.
     
  11. TwangerWannabe

    TwangerWannabe Tele-Holic

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    Shielding paint works if done correctly. I've used shielding paint on a couple guitars and a precision bass, all have single coil pickups. It absolutely works as long as you use the product properly and then also proceed to shield the guitar correctly. But just slapping shielding paint in a cavity and not taking the time or understand how to ground everything properly isn't going to change anything. Single coil hum will obviously still be there (they are single coils, stupid!) but everything else is dead quiet.

    And I haven't noticed any negative consequences (loss of tone, signal degradation, etc.) of properly shielding and grounding a guitar or bass, unless less noise is a negative to you.
     
    Last edited: Oct 13, 2020
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  12. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Shielding is cheaper than pickups and takes about as long to apply as it takes to swap pups (paint takes longer). It has always worked well for me with minimizing emf. It isn't going to make single coils silent, but on the other hand, I had fender noiseless pups on 2 guitars (N3 and Gen 4) and removed them because I didn't like the squawky tone I got from them. To me, they were quiet, but missing something - not only noise. To each their own.
     
  13. chris m.

    chris m. Poster Extraordinaire

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    Shielding with copper foil tape makes a really audible difference in reduced noise and hum if done properly. I also like to use shielded cable from the wiring cavity to the output jack. The one down side of a shielded cavity is that it is fairly easy to have a hot connection, such as at the pickup switch, ground to the shielding when you put the control plate back into place. I usually end up using a little bit of black electrical tape on top of the shielding in a few key spots to avoid this issue.
     
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  14. tubelectron

    tubelectron Tele-Afflicted

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    "Twist and Shield" ! Here made on my Squier CV50 2020 Indonesia :

    [​IMG]

    But it's me, OK ?

    -tbln.
     
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  15. schmee

    schmee Doctor of Teleocity Silver Supporter

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    I would say no. What the cavity shield does is create a faraday cage around most of the noise creating culprits.
     
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  16. chris m.

    chris m. Poster Extraordinaire

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    I don't think twisted pair does much at all. For example, your guitar cable is fully shielded, not twisted pair....if twisted pair actually did the job then they probably wouldn't bother with shielding.
     
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  17. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    Wow - very neat! Mine look like pre-school class projects...
     
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  18. Boreas

    Boreas Tele-Afflicted Silver Supporter

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    I think it makes a bigger difference in amps with higher energy electrons dancing around, and everything encased in a big can. Some techs just carried it over to guitars. But it does neaten up the guts nicely!
     
  19. chris m.

    chris m. Poster Extraordinaire

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    I agree that lead dress matters in amp enclosures and even pedals, possibly. Given the nature of guitar wiring I think untwisted leads are a tiny fraction of the sources of hum and noise and therefore twisting them doesn't do much.
     
  20. tubelectron

    tubelectron Tele-Afflicted

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    Thanks @Boreas ! ;)

    Twisting and shielding makes that CV50 insensitive to adverse noises :cool:. It was not the case as is o_O.

    - shorting the wires as best, and make a wiring as direct as possible, in logical order.
    - twisting them if shielding is not possible.
    - shielding them when possible.
    - shielding the cavities the Faraday way (= closed shielding as far as possible).

    Nothing new here : I just use old rules, very common and efficient in AF and RF circuits... :)

    That said, I front scratching-noise switching problems with the Hosco 3-way switch... :mad:

    I plan to replace it ! CRL ? Others ? What do you Guys use ? o_O

    But it's me, OK ? :D

    -tbln.
     
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