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Shielding the pickups cavities... Is it detrimental to tone quality?

Discussion in 'Tech-Talk' started by chillaxboi, May 6, 2010.

  1. chillaxboi

    chillaxboi Strat-Talker

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    Is it detrimental to tone quality to shield the pickup cavities? I read somewhere it takes away a bit of clarity but don't know if this is true.
     
  2. woodsie831

    woodsie831 Senior Stratmaster

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    i didnt notice any loss but i also upgraded pickups at the same time.
     
  3. LukeM

    LukeM Strat-Talker

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    It adds capacitance, which adds mud, which reduces clarity.

    I've said it once and I'll say it again, good grounding is all you need.
     
  4. problem-child

    problem-child Senior Stratmaster

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    I say no.

    LukeM; I'm not sure I'm buying the capacitance argument. I can't see where any capacitance is introduced into the signal path. Instead I see the wiring and controls existing inside the Faraday Cage which in essence would mean they exist inside the dielectric (air) of the "capacitor" that is being created by shielding both the pick guard and the cavities.

    I'll give you that it's been 15 years since I studied electronics so I could well be wrong...

    Feel free to educate me.
     
  5. LukeM

    LukeM Strat-Talker

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    The dielectric, in this case, is air, with a constant of 1.00054.

    So, it's reasonable to assume that because you have 2 parallel plates with an area A (copper foil on the pickguard --Plate #1, and copper foil in the cavity -- Plate #2, each with their own area, held parallel with 8 to 11 screws), and a distance separated by distance 'd' (I don't know what the distance is between a pickguard screwed down on top of a guitar body, but it's damn near nothin'...), that there is capacitance within the circuit.
     
  6. problem-child

    problem-child Senior Stratmaster

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    Yeah in my original post I said the same thing that those two plates and the air in between created a capacitor and then we put the controls and wiring inside that dielectric. By the way that constant 1.00054 has got to be related to some other variable (volume/distance) I'm thinking.

    I was rethinking this last night and in reality if the two plates we have described actually share the same potential "d" = 0 (with respect to the circuit) and the should. I'm not sure that we are really creating that capacitor to begin with...

    Anyway LukeM, I'm not trying bust your balls here. This is just an interesting topic for which we share different opinions. I'm have posted my contrary opinion in other threads you have posted in about the subject and wanted to go a bit deeper here.

    In the end, I'm no electrical engineer and don't work with this stuff at this level enough to provide a definitive answer. In answer to the original post I can just say what my experience has been. In the past I've done this to a very bright guitar hoping for some attenuation of the higher frequencies and it never happened.

    I would say try it. If it works for you great. If it doesn't work for you then it's very easy (and cheap) to reverse.
     
  7. jflintmac

    jflintmac Most Honored Senior Member Strat-Talk Supporter

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    Isn't that shielding to reduce Hum?
    I always thought that tone was generated through the bridge, into the wood and into the..... Ahh, I see what you mean!
    Just kiddin'
    But you may have a point. One thing is sure, you don't want any of that sheilding to be loose or it may add some really nasty sound. - Heavy Metal!!
     
  8. Stratplayer

    Stratplayer Senior Stratmaster

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    I agree with problem-child. As long as the cavity and pickguard are completely shielded and the pickguard side of the shielding has plenty of area with which to make contact with the cavity shielding so there is good electrical continuity between the two sides (particularly in areas adjacent to the pickguard screws so they make good, solid contact), and also the adhesive on the shielding is electrically conductive, and the shielding is grounded, there is no chance that it could act as a capacitor. It will be no different than the grounded metal enclosure on most stompboxes or the grounded metal chassis on your amp. I also used to study electronics and work with them in the military but since I ended up in the HVAC field over the past 11 years it has been a while since I studied electronics at that level too.
     
  9. jflintmac

    jflintmac Most Honored Senior Member Strat-Talk Supporter

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    Not to change the topik or hi-jack the thread but...
    Q - So is there a big difference between the copper sheilding and Alluminum?
    After all , my pickguards are all sheilded with alluminum.
     
  10. paleus

    paleus Strat-O-Master

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    Even if there is some capacitance, it is not enough to outweigh the benefits of having a quieter guitar. If it hurt the tone that much nobody would be shielding their guitars.

    If I understand your argument correctly LukeM, you are saying there is capacitance in the space between the shielding on the pickguard and the shielding in the cavity. If done correctly, the shielding should be one continuous circuit when the pickguard is on the guitar by making sure the cavity shielding makes good contact with the pickguard shielding when the guitar is assembled. Wouldn't that just be a normal circuit? Assuming they are making good contact.

    jflint, I wouldn't think that the material would make that much of a difference as long as it is conductive. I may be totally wrong but I would think as long as it is a conductive metal it would work just the same as any other.
     
  11. Stratplayer

    Stratplayer Senior Stratmaster

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    Silver is the most electrically conductive known metal there is, followed in order of conductivity by copper, annealed copper, gold, and aluminum. All of them are quite conductive enough to get the job done.
     
  12. LukeM

    LukeM Strat-Talker

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    You're assuming those two metal plates touch. This is merely from my experience too: my friend had me change out the electronics for him on his 'shielded' Strat. I measured the difference between the two plates at around 0.04uF. Sure, you might be able to play with that, but if you're sitting there with already 0.04uF to ground, you won't be getting much of a high end through.

    Well seated grounds, with all metal objects grounded (switch, pots, etc) and you can minimise it. However, you're playing with 60 cycle hum, there's not much you can do with that.

    The way old guys did it was when you're not playing, have your volume on 0, then when you are playing, it's virtually unnoticeable. Eric Clapton doesn't claim his tone was so great on the Beano album because he shielded his guitar, does he? No, of course not.

    Fenders and Gibsons in the 50s were NOT shielded.
     
  13. Stratplayer

    Stratplayer Senior Stratmaster

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    I'm not trying to be argumentative here at all, but how on earth do you measure this capacitance with the pickguard on and screwed down tight? And no, guitars from the 50's may not have been shielded all that well (even the '54 strat had the pots and switch mounted to the pickguard through a metal plate, and other Fender models had the controls mounted to a metal plate) but then the quality of the recordings from that era isn't great enough to have picked up the extra noise is it?
     
  14. ERICJOHNSTON

    ERICJOHNSTON New Member!

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    re shielding pickup cavities,i am not aware that this was detrimental to to tone quality,as most of the tonal ambience is determined by a number off factors,the actual body composition,the overall sustain,for example have you fitted a brass nut in place of the plastic one? The type of strings, and even the finish. Acrylic is the death knell of tonal quality.bear in mind that no solid guitar regardless of price will ever have the tonal response of an accoustic guitar,simply because of the way it is built

    eric johnston
     
  15. Stratplayer

    Stratplayer Senior Stratmaster

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    We were talking about the (absurd in my opinion) idea that copper or aluminum foil tape used as shielding, even when properly done, can act as a capacitor and electrically affect the tone of the signal the guitar produces, like the capacitor on a tone control.

    Here's another thing to think about: On a tone control's capacitor, one lead is connected to the + signal from the pickup (through the pot), and the other lead is connected to ground. Therefore, the capacitor and pot act as a variable filter through which the high frequencies (which frequencies depends on the value of the capacitor in uF, or microfarads) can be passed to ground. The shielding, if properly done, will ONLY be connected to ground--in NO way does it have any connection to the + signal from your pickup. So how is it supposedly going to affect the tone of your signal?
     
  16. Phat-O-Caster

    Phat-O-Caster Strat-O-Master

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    from Guitar Nuts: GuitarNuts.com - Shielding a Strat(tm)

    "Shielding and regrounding your guitar will not signficantly alter its tone, other than that it may sound a bit more alive because faint harmonics that were buried in hum can be heard more clearly when the hum is removed. Also, you will typically be able to play at higher gain levels before hum becomes objectionable. This means more tube saturation and sustaining feedback. These instructions have been online at various URLs since early in 1996. During that time I have never received an e-mail from anyone who wanted to know how to put the hum back into their shielded guitar!

    Probably the greatest benefit of reducing hum is the accompanying increase in sustain and dynamic range. As you reduce hum you can crank the gain higher on your amplifier before the hum becomes intrusive. With the increased gain you get better sustain and you can vary your picking attack for much better dynamics as you play."

    I found these statement to be absolutely true in my case-Brian
     

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  17. drf64

    drf64 Strat-Talker

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    I'll have to disagree on several points.

    First to be truly grounded, I connect the plates (pickup shield and body cavity shield) completely by soldering a wire from the scratch plate connected at one pup selector switch screw to the crimp ring in the body cavity.

    Second, if there is any mud, I can't hear it. That's all that matters to me

    Third, I've had tried just shielding the pickguard and not the body cavity with star grounding. It was a fair reduction of hum. I then went back and shielded the cavity. The result was incredible: much quieter, no sacrifice in tone.

    Fourth, Clapton played a LP on the Beano album and I think it had humbuckers so hum probably was diminished anyway.


    Just my opinion.

    regards,
    dan
     
  18. Astro1176

    Astro1176 Senior Stratmaster

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    Shielding benefited my Baja tele tremendously, it is still a bright attacky guitar, and it reduced the hum, especially that buzz when you are not touching the strings. My CV Strat was already shielded, as are a lot of the guitars you hear on hit records and your favourite albums.

    Its one of those cases where some scientists say something might be bad, but they are missing the real world factors that make it great.
     
  19. Andy54

    Andy54 Strat-Talker

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    Short answer ~ No.
     
  20. scotzoid

    scotzoid Senior Stratmaster

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    It's complicated, but in theory, lukem is right - anytime 2 conductive surfaces are close together without touching, there is capacitance, & if one of those surfaces is grounded, that capacitance will take some of the high freqs away; there's capacitance in cables too, long runs of low-grade cable will suck some high end away as well.

    Notice I said he's right, in theory - in real world terms, there's not enough current being bled off to make it muddy, unless maybe you've got dog ears...and I think we've heard from enough people who have shielded their guitars, & are happy with the results (myself included) to say that any supposed tone change is well worth the effort.
    The old guys had to use the outhouse too. I'm not giving up my indoor plumbing just to be like them.
     
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