FDP Forum / Shielding Question (Classic Series Strat)/ 9 messages in thread.

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BluesDood



United States

Blues Dood
Jun 8th, 2017 12:41 AM        

I just bought a new classic series 60's strat and I decided to take it upon myself to look into some resolutions to some noise issues I was having. I already had some copper tape lying around and upon opening up the guitar I saw that the guitar had no shielding in the pickup or tone pot cavities. <br /> <br /> So about 3 hours later, the guitar was pretty much setup and ready to go. I'm a little bit torn though, as though the noise has been decreased tremendously, I also find the guitar now lacks some of the top-end it had which made it such an aggressive and and mean sounding guitar. It sounds more "modern" with the treble frequencies reduced slightly.<br /> <br /> Likewise, I installed an aluminium pickguard to place underneath the non-shielded pickguard I purchased, but as it turns out the pickguard it came with is shielded anyways so not only was it an unnecessary purchase, but now I'm questioning which factor is playing into what I'm hearing.<br /> <br /> So again the question, is the copper tape or aluminum pickguard causing this high end roll-off? Or is it a combination of both? Any thoughts would be appreciated, as I think I preferred the way the guitar sounded before, even with the cost of noise.



DrKev

Contributing Member
*****

Paris, France

It's just a guitar, not rocket science.
Jun 8th, 2017 03:06 AM        

No, cavity shielding does not cause high end roll off. Sheilding the pickup themselves, a different story, but not the cavity/routing. <br /> <br /> This is something you'll read a lot on the interwebs about sheilding guitars. Personally, I think most of it is expectation bias. We read this can happen and our listen for it. And when we expect something that is slight (as you say) or subtle and we have no way of doing an A-B comparison and rely on memory and are listening to/for something specific, we often hear things differently, even if listening to exactly the same thing.<br /> <br /> See first three minutes of below link...



ejm



usa

Jun 8th, 2017 08:51 AM        

I agree with DrKev. This phenomenon has been discussed several times on this forum. The first time I ran across is was yearzzzz ago. If anyone remembers Bill Turner, I think he was in on it.<br /> <br /> It has also been discussed as to whether or not it makes a difference as to aluminum versus copper, and/or which is more effective. I don't know, and probably don't care.<br /> <br /> I am a firm believer that if all you do is shield the pickguard and nothing else, it makes a noticeable difference in noise rejection and is worth doing. I personally heard/saw it many years ago using two guitars, side by side, one shielded and the other not. I have shielded all of my guitars since that day.<br /> <br /> Someone on here once commented that the "loss of highs" you are hearing is really the loss of noise (notice I said noise, NOT hum, they are not the same). I can see how that could be true.<br /> <br /> As the Dr said, sometimes we think we hear things that are not there. Unless the guitar is now dull, which is different from a loss of highs, play on.<br /> <br /> If you think you hear a difference, you can always rip out the shielding you added. I'd start with removing the cavity first and leave the shielding on the pickguard, but that's me.<br /> <br /> What the Doc said about an A-B comparison is also true. If you really want to do a science project, you can record the various configurations so you can listen back to them, analyze them with a DAW, etc.<br />



BluesDood



United States

Blues Dood
Jun 8th, 2017 10:44 AM        

Thanks for your responses Dr Kev & ejm, I expected others to affirm what I thought, I'm somewhat glad that my fears where challenged. <br /> <br /> I will mention what ejm said though, I think maybe the noise reduction makes it seem/feel like I'm losing something in the sound, when it may just be all that the noise I'm not hearing.<br /> <br /> Either way, I spent like I said 3 hours doing the pickup cavity by hand with copper tape, I'd hate to have to un-do all that work, and the noise was cut tremendously after so it may be keeping it for practicality anyways. Thanks for y'alls responses, I may put the original pickguard back on and see what happens, but I don't think I want to remove the copper shielding I added in the pickup cavity if I can help it, that stuff takes work!



Steve Dallman

Contributing Member
**********

Merrill, Wisconsin

Age is just a number...mine is big
Jun 9th, 2017 07:23 AM        

There is a psycho-acoustic phenomenon when if there is noise in an audio signal, it changes how we hear the audio. For example, hiss in a signal, tricks our brains into thinking there is more high end in the audio. Even when you are playing, and the audio signal swamps out the noise, the noise is still there and affects how we perceive the sound. <br /> <br /> I was going to completely shield some single coil pickups as I had already done the cavities, but wanted more noise cut. I took off the covers and wrapped the coils completely with aluminum tape. I DID find the treble was affected. So I removed the shielding from the pickups, leaving the cavity. <br /> <br /> I experimented then by running a ground wire to a length of the thin aluminum tape. I played the guitar, slipping the tape between the strings and pickups. The tape did noticeably cut the highs. When shielding, I now only wrap the sides, not the face. <br /> <br /> I have not noticed a change in treble when shielding the cavities and/or pickguard. I've used shielding paint, aluminum, brass or copper over the years.



Leftee

Contributing Member
*****

VA

Jun 9th, 2017 10:16 AM        

I copper shielded a Strat clone cavity 10+ years ago. I no longer have the guitar. I noticed a loss of "airiness" in the tone which I attributed to loss of noise. <br /> <br /> I kinda wonder if I would even notice today. My hearing has declined. Especially my high end.



FunkyKikuchiyo



VT

Jun 9th, 2017 08:02 PM        

I'll echo what Dr. Kev said.<br /> <br /> Any roll off experienced is from a phenomenon called eddy current loading. When a conductor is placed in a magnetic field it creates a strange resistance in the circuit. This is why humbuckers sound different depending on if they have a cover or not, as well as a whole mess of other design choices in pickups. <br /> <br /> Cavity shielding is too far from the magnets to have any substantial impact on the tone. That is why DrKev points out that if it is on the pickup itself it is a different story.<br /> <br /> Though you may not have the correct instruments, this CAN be measured. Eddy current loading shows up if you measure resistance with an AC test frequency, 1 kHz being the most common. I can hook a pickup up with test leads and get different readings as I put covers on and off. I even have changed readings by cutting lines in surrounding shielding so it can't "loop". I've never tested it on a strat like this before, though I'd be curious if it even shows up.<br /> <br /> "Likewise, I installed an aluminium pickguard to place underneath the non-shielded pickguard I purchased, but as it turns out the pickguard it came with is shielded anyways so not only was it an unnecessary purchase, but now I'm questioning which factor is playing into what I'm hearing."<br /> <br /> Did you put the aluminum plate on there anyway? (I spell it that way because I'm Murrikan). I ask because doing so would mean removing the pickups and remounting, potentially at different heights. If you're hearing something, you may be hearing pickups that are too low. <br /> <br /> Also, the biggest differences between aluminum (Murrika) and copper for these purposes is going to be workability and which one makes more sense. On a pickup is a whole 'nother ball of wax, but both are plenty conductive for shielding.



BluesDood



United States

Blues Dood
Jun 9th, 2017 09:58 PM        

As it turns out, it was indeed the aluminum plate that was causing the issue, and likewise blocked much more noise than the cavity did, go figure. So I ditched the plate and put on the old pickguard and the guitar is good as new!



Peegoo

Contributing Member
**********
**********
******

I walk

between the raindrops
Jun 10th, 2017 07:58 AM        

Cool!<br /> <br /> In addition to eddy current loading caused by ferrous and non-ferrous metal in proximity to a magnetic field (as described by funkykikuchio above), there is also capacitive coupling between the coil and metal in close proximity to it. <br /> <br /> The key word is "close" proximity, because a milimeter makes a huge difference. <br /> <br /> In the 80s I experimemted with full shielding on single coil pickups and discovered that wrapping copper foil around the coil did cause a loss of highs. <br /> <br /> When I wrapped a few layers of tape on the coil first, followed by the copper, highs were preserved. It didn't take much tape at all, but it made a big difference.<br /> <br /> So shielding can affect tone in two ways: magnetically and electronically--even though magnetics IS electronics :0)



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