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Terry McInturff
02-08-2011, 09:04 AM
Hello all,

I am a firm believer in shielding a non-vintage guitar as completely as is possible.

What is meant by shielding? It means that...as much as is possible...the pickup cavities, the pickups, the controls...are all surrounded by an electrically conductive metal foil, paint, etc that is grounded. A good job of this will substancially reduce the amount of Radio Frequency (RF) buzz and interference that will come out of the speaker cabinet.

It can make a big difference. All sorts of RF can create havoc...not only from radio stations, but also from light dimmer packs, flourescent lighting, and even digital cash registers!

While I personally recommend conductive paint..applied liberally, in multiple coats...adhesive-backed foil can work too.

Main aim...surround all components as much as is possible...test to make sure that all shielding is connected to ground...also to make sure that no accidental grounding-out of any component can happen via the shielding should a securing nut happen to come loose, etc.

Myth: Shielding will change the tone of the guitar
This is only true if you consider RF noise to be a part of the musical tone of a guitar. I consider RF to be unmusical noise. Totally undesirable.
Common error: not doing a neat and thorough job, not grounding the shield properly
Remember that the goal is to surround the components with what amounts to a grounded, conductive enclosure...technically, a Faraday Cage. The shield must readily conduct electricity (test with a VOM) AND be connected to ground via sturdy means.
Tip: how to paint internal wire holes
Pipe cleaners make a good "brush" for this.

Shielding will not detract from your tone. Arguably, the tone will be improved.

Great shielding + Excellent electrical components + world-class wiring = totally professional work "under the hood" :)

Im painting on shielding today, and so this topic came to mind.

Diablo
02-08-2011, 09:31 AM
Hey Terry,
Great post idea once again. I have always found that the single coil guitars, especially P90s, benefit a great deal from sheilding. Humbuckers, I haven't noticed so much. I have done it with copper tape soldered together which works quite well. What kind of sheilding paint do you use and where do you get it? I have used the Stew Mac stuff before but it was quite expensive for such a small amount if I recall. I have looked at industrial electric supply places but didn't know exactly what to ask for. I'll have to do some testing now that you brought this up regarding humbuckers and sheilding. Thanks again for the informative posts buddy!

amc
02-08-2011, 09:58 AM
once again, thank you terry for your informative post......................

as a side note: i own and happily play instruments built by both terry mcinturff and joe driskill (diablo).

Terry McInturff
02-08-2011, 09:59 AM
Thanks Joe!
I do use the paint from Stew-Mac; it is from Germany and is called Electrodag. Maybe we can find a good OEM source.

I agree that the biggest benefit is on single coil equipped guitars; but humbucker-equipped benefits as well, due to the fact that any unshielded wiring in the control cavity picks up RF.

One thing that I see time and time again is an OK shielding job in the guitar...but the underside of the coverplates arent shielded.

I also see conductive paint that does not make a clear ground all the way to the jack. This is usually due to not applying enough paint...and obviously from not testing it with a VOM after the paint is dry!!!

Just MY opinion...these are electric guitars...isnt it right to expect outstanding electrical craftsmanship?

claycastle
02-08-2011, 10:10 AM
I completely shielded the interior guts of a Kramer Focus (pick guard with single coils)with the copper tape. Took quite some time to do it right. No difference! Still makes the same noise. Still gets the same interference.

Pfeister
02-08-2011, 10:13 AM
I completely shielded the interior guts of a Kramer Focus (pick guard with single coils)with the copper tape. Took quite some time to do it right. No difference! Still makes the same noise. Still gets the same interference.

Did you ground the shielding to the rest of the electectronic setup? That's absolutely necessary.

Terry McInturff
02-08-2011, 10:29 AM
I completely shielded the interior guts of a Kramer Focus (pick guard with single coils)with the copper tape. Took quite some time to do it right. No difference! Still makes the same noise. Still gets the same interference.

This could be due to:
1) An expectation that shielding will reduce 60Hz hum..it will not..only RF
2) Your shielding isnt grounded well
3) A ground loop in your guitar's circuit
4) A ground loop in your system
5) On and on...

Ahess86
02-08-2011, 10:33 AM
I also see conductive paint that does not make a clear ground all the way to the jack. This is usually due to not applying enough paint...and obviously from not testing it with a VOM after the paint is dry!!!


Hi Terry,

This is a relatively new and interesting topic to me. I'm curious, how do you connecting your shielding paint to ground?

Terry McInturff
02-08-2011, 10:46 AM
Hi Terry,

This is a relatively new and interesting topic to me. I'm curious, how do you connecting your shielding paint to ground?

At times Ive relied upon the cases of the pots, switches, etc to make the connection, but I have to say that this is not the very best way. The BEST way is to solder a wire to a lug, solder the other end of the wire to a good ground, screw that lug to the wall of the control cavity, and then paint over that connection. This...plus the connections gained from the pot cans, etc...is best. IMO :)

frquent flyer
02-08-2011, 11:29 AM
I have heard of copper foil and/or a carbon based spray being used...I know shielding works well..more builders should use it.

Terry McInturff
02-08-2011, 11:34 AM
I have heard of copper foil and/or a carbon based spray being used...I know shielding works well..more builders should use it.

I agree that good shielding ought to be S.O.P.

The carbon based sprayed paint is OK...however, it can go on too thin, and not be a great shield. Of course, more coats can be applied. There are sprayable metallic-based paints, and these seem to provide a better "one-pass" result.

AudioWonderland
02-08-2011, 12:02 PM
Oh Hell I went nuts and did 3 coats of stewmac paint and then applied Stew mac copper tape with the conductive adhesive over the paint on my strats. It was everything I wanted and more. The noiseless pickups just did not sound right and the DAW CRT still caused issues. After shielding I had to locate myself so the pickups were off access from the CRT but once I did it was quiet. I later replaced the CRT with a flat screen and it got even better.

I have always felt like just a tiny bit of treble is lost when the shielding is done but I also consider that a plus. Strats always seem a touch bright to me

Pscheoverdrive
02-08-2011, 12:18 PM
If you REALLY trusted your shielding job, you could theoretically just ground everything to the shield... Pots, pickups, bridge, output jack, etc.

I used to use aluminum foil and spray-glue on some of my early guitars. It actually worked pretty well and was a heck of a lot cheaper than shielding paint or tape, but looked pretty DIY.

Maybe somebody should start making metal pickup cavities and control cavities that could just get dropped into the guitar, and then grounded. I'd trust something like that for a ground-to-chassis kind of wiring job.

Terry McInturff
02-08-2011, 12:24 PM
If you REALLY trusted your shielding job, you could theoretically just ground everything to the shield... Pots, pickups, bridge, output jack, etc.

I used to use aluminum foil and spray-glue on some of my early guitars. It actually worked pretty well and was a heck of a lot cheaper than shielding paint or tape, but looked pretty DIY.

Maybe somebody should start making metal pickup cavities and control cavities that could just get dropped into the guitar, and then grounded. I'd trust something like that for a ground-to-chassis kind of wiring job.

Agreed. The only reason why grounding to the shield isnt a great idea is the probs regarding connections to the shield..especially with paint. But yes...a good shield is essentially part of the ground bus.

For a number of years, Gibson fitted LP's etc with a metal can for the control and switch cavities. These worked well.

Pscheoverdrive
02-08-2011, 12:40 PM
For a number of years, Gibson fitted LP's etc with a metal can for the control and switch cavities. These worked well.

Better than those POS PCBs in them now, I imagine... :\

rah3
02-08-2011, 12:50 PM
Come on Terry! Noise is an essential element in the Sonic Pantheon of Rock and Roll guitar!

- RAH3

Tidewater Custom Shop
02-08-2011, 02:24 PM
My current Strat is the most quiet I ever owned. It didn't start off that way. I had a full aluminum shield and everything properly grounded, but it still had some issue that would go away when I touched the strings or anything metal.

So, I got a small can of that StewMac stuff and applied 2 coats to the pickup cavities, the elex compartment, even the output cavity. After it was dry (next day), I reattached my ground strap (from the pickup ground cluster on the V pot) to the elex cavity side wall and buttoned it up.

To me, the StewMac paint was the magic touch. Call it snake oil, but my Don Mare pickup loaded Strat is almost as quiet as my properly grounded humbucker loaded Les Paul. My Telecaster is next for the treatment!

claudel
02-08-2011, 03:00 PM
Anybody try this stuff?

Acheson Electrodag SP-008A

http://hitecfinishing.com/page89aaaa.html

There's a 'Bay seller with small jars, cheaper than SM...

Oz Hofstatter
02-08-2011, 03:18 PM
Thanks for share Terry!
Best,
Oz

Super Locrian
02-08-2011, 03:58 PM
I do use the paint from Stew-Mac; it is from Germany and is called Electrodag.

I'm in Norway, I don't think I can order chemicals from abroad. I've found some Electrodag products available locally, which of these would you recommend (link to datasheets)?

Electrodag 440 AS (http://www.oo.no/admin/common/getImg2.asp?Fileid=1391)

Electrodag 1415M (http://www.oo.no/admin/common/getImg2.asp?Fileid=1390)

Great topic, thanks for the very useful info!

AudioWonderland
02-08-2011, 04:24 PM
If you REALLY trusted your shielding job, you could theoretically just ground everything to the shield... Pots, pickups, bridge, output jack, etc.

I used to use aluminum foil and spray-glue on some of my early guitars. It actually worked pretty well and was a heck of a lot cheaper than shielding paint or tape, but looked pretty DIY.

Maybe somebody should start making metal pickup cavities and control cavities that could just get dropped into the guitar, and then grounded. I'd trust something like that for a ground-to-chassis kind of wiring job.

You sure can and I do.


http://members.toast.net/dwyss/pics/Assembledguard1.jpg
http://members.toast.net/dwyss/pics/Assembledguard2.jpg
http://members.toast.net/dwyss/pics/bodyshield1.jpg
http://members.toast.net/dwyss/pics/bodyshield2.jpg

xntrick
02-08-2011, 05:13 PM
there is no ground with my EMG 81x, how do i effectively use copper tape i such a situation?

walterw
02-08-2011, 07:26 PM
I have been using Y- shield. It seems to work great. It is not cheap !

http://www.yshield.com/
shielding wall paint?

does it keep the CIA from reading your thoughts? :rotflmao

walterw
02-08-2011, 07:28 PM
there is no ground with my EMG 81x, how do i effectively use copper tape i such a situation?
EMGs typically do not need extra shielding, which is why they can get away with not grounding the strings. (the pickups themselves are very much grounded.)

if you did want to shield, just ground the shielding like you normally would.

walterw
02-08-2011, 07:32 PM
This could be due to:
...
3) A ground loop in your guitar's circuit
...

a ground loop in a passive guitar circuit? :huh

how could that happen, when there's only one possible ground potential, the shield of the guitar cable?

D Rhinehart
02-08-2011, 07:53 PM
Hello all,

I am a firm believer in shielding a non-vintage guitar as completely as is possible.

What is meant by shielding? It means that...as much as is possible...the pickup cavities, the pickups, the controls...are all surrounded by an electrically conductive metal foil, paint, etc that is grounded. A good job of this will substancially reduce the amount of Radio Frequency (RF) buzz and interference that will come out of the speaker cabinet.

It can make a big difference. All sorts of RF can create havoc...not only from radio stations, but also from light dimmer packs, flourescent lighting, and even digital cash registers!

While I personally recommend conductive paint..applied liberally, in multiple coats...adhesive-backed foil can work too.

Main aim...surround all components as much as is possible...test to make sure that all shielding is connected to ground...also to make sure that no accidental grounding-out of any component can happen via the shielding should a securing nut happen to come loose, etc.

Myth: Shielding will change the tone of the guitar
This is only true if you consider RF noise to be a part of the musical tone of a guitar. I consider RF to be unmusical noise. Totally undesirable.
Common error: not doing a neat and thorough job, not grounding the shield properly
Remember that the goal is to surround the components with what amounts to a grounded, conductive enclosure...technically, a Faraday Cage. The shield must readily conduct electricity (test with a VOM) AND be connected to ground via sturdy means.
Tip: how to paint internal wire holes
Pipe cleaners make a good "brush" for this.

Shielding will not detract from your tone. Arguably, the tone will be improved.

Great shielding + Excellent electrical components + world-class wiring = totally professional work "under the hood" :)

Im painting on shielding today, and so this topic came to mind.

Great topic, I shield with the StewMac Conductive coating. True it is a little pricey , but for ease of installation you cant beat it. Also I use Aluminum as opposed to copper , again a little cheaper in conjunction with the conductive coating ( for pickguards and access covers ) . I shield everything , singles ,hums etc., making sure I Ohm out the entire circuit.
Again great post .:agree

thesjkexperienc
02-08-2011, 11:50 PM
Thanks to the OP. I have used a combination of paint and copper to shield my three Strats and I think they all sound fantastic. I also got rid of the static sound on my single ply guard Strat.

Now I have what is my first keeper Tele and it is just like the old ones with no shielding. It is an LsL and the only serial numbers, other than the name of the guitar Maya, are written on the inside. I havent popped the neck to check there, but I do want to shield it mostly to get rid of the static noise!

I have rather high action on top of the LsL philosophy of designing for keeping a big break angle at the saddles. So, my pickups are almost as high as they can go and I don't know if I will get any benefit from shielding anything other than the pickguard. Would this be true?

michael30
02-09-2011, 01:37 AM
I'm in Norway, I don't think I can order chemicals from abroad.

I ordered the conductive paint from Stew-Mac. There shouldn't be a problem as long as you don't order flammable liquids or pressurized containers.

Be aware that the Stew-Mac paint will go bad if it sits in the can for a long time without being shaken or strirred.

Terry McInturff
02-09-2011, 06:33 AM
a ground loop in a passive guitar circuit? :huh

how could that happen, when there's only one possible ground potential, the shield of the guitar cable?

You got me there Walter...yet another example of my unclear writing.
What I SHOULD have written was:
1) A ground loop in your guitar rig's circuit
2) A ground loop involving your AC system

ManliusGuitar
02-09-2011, 06:51 AM
I don't think you can say that shielding will not have an affect on the overall tone of your guitar. It just isn't the case. If the pickups are included in this and shielded, there will be a change in the treble response of the pickup...

It is a pretty easy experiment, take a single coil and drop it in a guitar and play it and listen. Then shield and ground the pickup, drop it back in and play it and you will hear quite a bit of difference. It isn't necessarily good or bad, but it IS different.

So you can't say that shielding is completely non-invasive to the tone on an instrument, as long as the pickups are part of the shielding process.

AudioWonderland
02-09-2011, 07:22 AM
I don't think you can say that shielding will not have an affect on the overall tone of your guitar. It just isn't the case. If the pickups are included in this and shielded, there will be a change in the treble response of the pickup...

It is a pretty easy experiment, take a single coil and drop it in a guitar and play it and listen. Then shield and ground the pickup, drop it back in and play it and you will hear quite a bit of difference. It isn't necessarily good or bad, but it IS different.

So you can't say that shielding is completely non-invasive to the tone on an instrument, as long as the pickups are part of the shielding process.

I don't think anyone was talking about shielding the pickups themselves though were they?

Terry McInturff
02-09-2011, 08:06 AM
I don't think you can say that shielding will not have an affect on the overall tone of your guitar. It just isn't the case. If the pickups are included in this and shielded, there will be a change in the treble response of the pickup...

It is a pretty easy experiment, take a single coil and drop it in a guitar and play it and listen. Then shield and ground the pickup, drop it back in and play it and you will hear quite a bit of difference. It isn't necessarily good or bad, but it IS different.

So you can't say that shielding is completely non-invasive to the tone on an instrument, as long as the pickups are part of the shielding process.

Let's perform a thought experiment. Remember that we are talking about surrounding the electronic components with a Faraday Cage...so, let's build one! :)

We will paint an entire room with conductive paint, and connect that paint to the same ground that our guitar and amp are using.

We begin playing outside of the room, and then we walk thru the door into the room, still playing.

As we enter the room, the frequency response of our guitar is unchanged...only the RF is greatly attenuated.

Tell you what....my spraybooth is a totally enclosed, sheet metal automotive type. I'll ground it and take a stroll in there with a guitar. I'll rig up a switch to make/break that ground too. I do not have recording facilities at my shop, so, you all will have to trust me when I report back regarding anything. I am ALWAYS ready to be proven wrong! That is part of being a "lifetime learner".

David Collins
02-09-2011, 08:40 AM
I started doing some tests on shielding materials, but kind of dropped the ball and didn't follow through due to time and quite honestly a loss of motive.

I typically use MG Chemicals Super Shield nickel paint spray, and the main motive for testing was to see how much if any difference several coats vs a single coat made. At $40 a can, and with the time spent on 3 or 4 coats vs 1, I just wanted to see if the additional layers really made a difference. So I made a quick/cheap/crude test box and coil.

http://annarborguitarrepair.com/images/shield1.jpg

Then with a channel cut in the board, a sprung contact strip in the channel, I can put a noise source (mainly a fluorescent desk lamp in this case) in front of the coil and slide different plates with different coatings through to compare in real time.

http://annarborguitarrepair.com/images/shield3.jpg

http://annarborguitarrepair.com/images/shield2.jpg

I didn't have any of StewMac's carbon shielding paint when I did this, but I used copper foil, aluminum foil, metal HVAC tape, and nickel paint in single and double coats, and four wet dripping thick coats. I only got as far as listening through some amps, and plugging it in to a spectrum analysis program, and basically saw no change between any of them in this admittedly crude comparison that motivated me to go much farther in testing.

This was all just to test effectiveness at eliminating noise, and not on whether it had any effect on tone. I bring it up mainly because of mention earlier of number of coats needed for effective shielding with the StewMac paint. As I said, I didn't try theirs, but with the nickel paint I found no discernible difference between one regular coat and four heavy coats. Perhaps the carbon paint may be less conductive, and therefore need a greater thickness to act effectively, but I don't know for sure. I'll get around to a similar test on their paint one of these days.

Seegs
02-09-2011, 08:45 AM
I don't think you can say that shielding will not have an affect on the overall tone of your guitar. It just isn't the case. If the pickups are included in this and shielded, there will be a change in the treble response of the pickup...

It is a pretty easy experiment, take a single coil and drop it in a guitar and play it and listen. Then shield and ground the pickup, drop it back in and play it and you will hear quite a bit of difference. It isn't necessarily good or bad, but it IS different.

So you can't say that shielding is completely non-invasive to the tone on an instrument, as long as the pickups are part of the shielding process.

agree with this...This was my experience after doing the Guitarnutz shielding method...used copper tape and measured for continutity in my connections...everything checked out...

the benefit was no noise/hum when I removed my hands from the strings...

the drawback was that I lost some high end...enough so that it was clearly audible and enough that it bothered me...

In my case the drawbacks outweighed the benefits...

I tore out the shielding and have never felt the need to shield my guitars since then...

Chow,
Seegs

David Collins
02-09-2011, 09:15 AM
I think it is worth separating the discussion of shielding pickup cavities, vs shielding control cavities.

If you shield a pickup cavity, within the range of movement of the magnetic field, then you can indeed be impeding movement of the magnetic field. Case in point, pickup covers, or Tele bridge pickup plates. They certainly will affect the tone. That said, those are some very thick plates (relative to the few thousandths of an inch we're typically talking about in shielding), and they are placed in extremely close proximity to the coil and magnets. As you move further out from the coil, and you thin the material to such a degree, the effect will drop exponentially.

Yes, there is the possibility that shielding a pickup cavity can have a real effect on how the field moves at higher frequencies. Realistically though, I would expect this change to be equivalent to a very small fraction of the change caused by a pickup cover or base plate. Maybe enough to be heard in some cases, but the accounts of dramatic changes I've heard from some people leave me to suspect that these small changes may sometimes be amplified by a person's expectations. Maybe not always, but I have certainly heard in the past some claims of change that just don't quite line up with realistic possibilities in my opinion.

When shielding a control cavity, this is different as you are far outside the effective range of the pickup's field. Now when you have a bunch of wires one side of a signal, stuffed inside a small Faraday cage grounded to the other side, you can add some capacitance to the circuit. Realistically though, I'd be surprised if shielding a complex cavity would amount ten picofarads added to the capacitance. The effect of this on tone would be the equivalent of lengthening an average guitar cable by 3 or 4 inches. So if you think that the tonal difference between a 15' and a 15' 4" cable might be too much of a sacrifice for cutting down on some noise, then maybe shielding the control cavity isn't for you.

I'd love to do some tests on shielding around coils. Shouldn't be too hard - a pickup, another non-magnetized coil above it hooked to a signal generator, and a little fold-up cardboard tray, shielded and grounded, to slide in and out from around the pickup.

Seegs
02-09-2011, 09:32 AM
the Guitarnutz method shields both pup and control cavities as well as the underside of the pickguard...

audible difference to me

Chow,
Seegs

Terry McInturff
02-09-2011, 09:39 AM
Great stuff David!

Let's think this thru....hmmm....shielding affecting a pickup's frequency response...

I just spoke to a tech at DiMarzio. His firm response was "shielding pickup cavities and control cavities will not change a pickup's frequency response".

PWE-Electric
02-09-2011, 09:49 AM
Proximity matters. A spraybooth will not simulate shielding that is close to the pickups and electronics.


Let's perform a thought experiment. Remember that we are talking about surrounding the electronic components with a Faraday Cage...so, let's build one! :)

We will paint an entire room with conductive paint, and connect that paint to the same ground that our guitar and amp are using.

We begin playing outside of the room, and then we walk thru the door into the room, still playing.

As we enter the room, the frequency response of our guitar is unchanged...only the RF is greatly attenuated.

Tell you what....my spraybooth is a totally enclosed, sheet metal automotive type. I'll ground it and take a stroll in there with a guitar. I'll rig up a switch to make/break that ground too. I do not have recording facilities at my shop, so, you all will have to trust me when I report back regarding anything. I am ALWAYS ready to be proven wrong! That is part of being a "lifetime learner".

beb
02-09-2011, 09:56 AM
Be aware that the Stew-Mac paint will go bad if it sits in the can for a long time without being shaken or strirred.
I had this problem, too. It doesn't go bad, it just loses moisture and turns into paste.

I called Stew-Mac about it. They said I could revive the paint with tap water. I tried it, and it works fine. Just add water to the sludge until it returns to its original consistency.

Also, Terry noted that he uses pipe cleaners for applying shielding paint to wiring channels. Another option--no better, but different--is to use q-tips, which are easy to find and cheap.

Arcane-Inc
02-09-2011, 10:06 AM
In most cases of standard shielding on guitars I don’t think it has a significant effect on the sound of the instrument. However I do believe the proximity, type of shielding and thickness of the shielding will have an effect on the sound if it is very close to the pickups. By close I am talking about within the magnetic field of the pickup.

If you place shielding that close you can see the Inductance change. I have done quite a few tests with James Trussart and different types of metal on or near the pickup and there is an audible difference, in some cases good in others not so good depending on the metal type and thickness. In the end our ears told us what to do, but I still do like to know why and how different metals change the sound of pickups.

If I have time later I will post some pictures of how inductance changes by having different metals close to pickups.

David Collins
02-09-2011, 10:07 AM
Great stuff David!

Let's think this thru....hmmm....shielding affecting a pickup's frequency response...

I just spoke to a tech at DiMarzio. His firm response was "shielding pickup cavities and control cavities will not change a pickup's frequency response".

I certainly agree there. If you are shielding with 1/16" mu-metal wrapped directly around the pickup, I'd say its pretty reasonable to expect a change. Shielding however is generally a thousandth or two thick, and positioned a relatively large distance from the coils and magnets. Without doing tests, all I guess I can say is that I'm rather skeptical that the change could directly cause much notable effect.

mullytron
02-09-2011, 10:07 AM
For those of you shielding P90-equipped guitars, do you shield the inside of the plastic cover? I never have, but I'm thinking about it on some upcoming jobs. I'm sure paint would be easier in this application, I've just always trusted foil more. Plus, you would need to solder a wire to the paint inside the cover, which seems impractical.

Also, is there any electrical reason not to use the foil inside a properly shielded and referenced control cavity as a ground plane? I have done it before, and it sure is easy, no sonic/performance issues that I noticed.

http://i1004.photobucket.com/albums/af163/mullytron/IMAG0247.jpg

ScottB
02-09-2011, 10:16 AM
Great stuff David!

Let's think this thru....hmmm....shielding affecting a pickup's frequency response...

I just spoke to a tech at DiMarzio. His firm response was "shielding pickup cavities and control cavities will not change a pickup's frequency response".

If you put additional metal in the vicinity of a guitar pickup's electro-magnetic circuit, it will change the frequency response and inductance. A Strat or Tele baseplate is a good example. Take a Strat pickup, put it on a table and measure it with and without a hunk of steel about 1/2" away. You will measure a significant and repeatable difference in AC electrical response. The pickup will inductively couple with any metal in the vicinity.

The question becomes at what distance, and mass and type of metal, does it become insignificant to the point that it can be ignored?

A good experiment would be to take a pickup, and put it in the middle of a grounded, copper lined box with symmetrical spacing from the pickup. Compare the AC electrical and frequency response of the pickup alone, with the response of the pickup in the grounded box. Do this with boxes of different sizes starting from say, pickup dimensions + 1/2" and increasing in 1/2" increments.

These data would put his question to bed for good. I've actually been meaning to do this, but I haven't gotten around to it.

Terry McInturff
02-09-2011, 10:26 AM
Remember everyone...I am talking about "real-world" conditions...using conductive paint or uber-thin foil for the shield. Of course...if we place a rather thick metal near the coil, the inductance will change. But, I'm not talking about that.

Also I want to mention that I respect the opinions of those who have heard a change in the freq response after shielding. If they hear it...it is there...and it doesnt matter if, electronically, the freq response has not been changed.

Just spoke to a tech at Lollar...when asked if shielding the pup cavities and the control cavities with paint or foil would change the freq response of a pickup, he replied "it should'nt".

Thus far we have a "no" from DiMarzio, and a "it shouldnt" from Lollar.

james russell
02-09-2011, 11:37 AM
I have a good friend who has been building guitars professionally since the 1970s. He originally worked at Alembic before going off on his own. He has told me on several occaisions that shielding paint will slowly lose it's shielding capability over time in the guitar. He said that he has had several of his guitars come back to his shop that were originally well shielded with paint and years later were picking up much more RF noise. At first he didn't believe it and looked for other explanations, but over time it happened on a number of guitars. He now prefers the foil shielding method. Several of his customers brought it to his attention seperately, complaining that their guitars were previously much quieter, and over time picked up more RF noise.

I haven't had personal experience with this, but have used the copper shielding successfully for many years now (though it is a pain).

Pscheoverdrive
02-09-2011, 12:05 PM
I lots of 'facts' stated and no math. Let's see some math! Real world results give just that - results... But not explanation. Perhaps the 'rolled off treble' is from blocked feedback as opposed to a change in frequency response. The guitar itself is not the only thing in the equation.

For those of you who hear a difference in the same guitar when it's shielded and when it's not shielded, can you hear the difference between a twisted/shielded wiring job and a non-twisted, point-to-point one? The twisting does almost the same thing as shielding, and obviously if you're using shielded wire, the signal's going to be shielded.

Terry McInturff
02-09-2011, 12:19 PM
I have a good friend who has been building guitars professionally since the 1970s. He originally worked at Alembic before going off on his own. He has told me on several occaisions that shielding paint will slowly lose it's shielding capability over time in the guitar. He said that he has had several of his guitars come back to his shop that were originally well shielded with paint and years later were picking up much more RF noise. At first he didn't believe it and looked for other explanations, but over time it happened on a number of guitars. He now prefers the foil shielding method. Several of his customers brought it to his attention seperately, complaining that their guitars were previously much quieter, and over time picked up more RF noise.

I haven't had personal experience with this, but have used the copper shielding successfully for many years now (though it is a pain).

Very interesting...thanks for your contribution! Inspired by your post, I opened up a 1983 TCM and tested the carbon based shielding paint. It worked as new, in this instance.

David Collins
02-09-2011, 12:27 PM
The question becomes at what distance, and mass and type of metal, does it become insignificant to the point that it can be ignored?


That's about where I stand - with a question I don't claim to have any final answers to. My gut says that in most cases I doubt that a thin shielding in an average size cavity will have any significant influence on tone. The information shared with Terry by the folks at Dimarzio and Lollar seem to agree with that. I'm willing to be surprised, but I just don't have the time to do any more tests to confirm or disprove anything right now.

David Collins
02-09-2011, 12:31 PM
I have a good friend who has been building guitars professionally since the 1970s. He originally worked at Alembic before going off on his own. He has told me on several occaisions that shielding paint will slowly lose it's shielding capability over time in the guitar. He said that he has had several of his guitars come back to his shop that were originally well shielded with paint and years later were picking up much more RF noise. At first he didn't believe it and looked for other explanations, but over time it happened on a number of guitars. He now prefers the foil shielding method. Several of his customers brought it to his attention seperately, complaining that their guitars were previously much quieter, and over time picked up more RF noise.

I haven't had personal experience with this, but have used the copper shielding successfully for many years now (though it is a pain).

Very interesting indeed. Is this tidbit of experience from Rick? There are few people who's opinion and experience I would trust more on things like this, so it could be enough for me to rethink using paint. I hate to do that though, because masking off and spraying a coat of magic in a can is just so much quicker and easier than lining with foil. ;)

AudioWonderland
02-09-2011, 12:49 PM
I lots of 'facts' stated and no math. Let's see some math! Real world results give just that - results... But not explanation. Perhaps the 'rolled off treble' is from blocked feedback as opposed to a change in frequency response. The guitar itself is not the only thing in the equation.

For those of you who hear a difference in the same guitar when it's shielded and when it's not shielded, can you hear the difference between a twisted/shielded wiring job and a non-twisted, point-to-point one? The twisting does almost the same thing as shielding, and obviously if you're using shielded wire, the signal's going to be shielded.

1) What is "blocking feedback"
2) The twisted shielding is not really the same. A faraday cage in total has much more mass and comes in close proximity to the pickups themselves. I would expect the likely hood of a faraday cage impacting things to be much higher.

I have always been of the understanding that any ferrous material that gets within the magnetic field of the pick will influence the eddie (sp) currents of that field. How much that impact things sonically I don't know. I would also think that there would be at least a little increase in capacitance. Do any of these combine into an audible difference? I don't know.

I think that since the noise consists of a lot of high end, once that's gone many people are perceiving that lost high end from the noise as a loss of high end in general.

ManliusGuitar
02-09-2011, 12:59 PM
Perhaps you are mis-interpreting the Faraday Cage and its effect on a guitar. You can certainly make your spray booth into a cage, and if it is constructed properly the instrument will sound, and i'll give you this, exaclty the same minus the noise.

But unless every musician wants to carry around a big grounded spray booth when they go play, this effect can not be achieved on electric guitar, and certainly not by just shielding the cavity and the pickups of an electric guitar. You must include the pickups into the construction of the 'onboard' Faraday Cage of the guitar, and this alone will alter the tone of the pickup.

The alteratioin of tone will be much slighter with humbucking pickups, which already have a grounding plate attached to them which serves in it sown way as a shield. You will really notice a difference with single coils.

Simply do the test I mentioned above Terry, and you'll hear it. I think the idea of a Faraday Cage is great, but it simply can't be instituted in a non-invasive way with an electric guitar unless the guitars pickups are not part of the construction of the cage, which I don't think is possible.

I know quite a few instruments, and i'm sure all the builders here who employ the pracitce have fantastic sounding guitars. But it is folly to suggest the shielding and cage doesn't have an altering effect on the tone of the electronics.

Let's perform a thought experiment. Remember that we are talking about surrounding the electronic components with a Faraday Cage...so, let's build one! :)

We will paint an entire room with conductive paint, and connect that paint to the same ground that our guitar and amp are using.

We begin playing outside of the room, and then we walk thru the door into the room, still playing.

As we enter the room, the frequency response of our guitar is unchanged...only the RF is greatly attenuated.

Tell you what....my spraybooth is a totally enclosed, sheet metal automotive type. I'll ground it and take a stroll in there with a guitar. I'll rig up a switch to make/break that ground too. I do not have recording facilities at my shop, so, you all will have to trust me when I report back regarding anything. I am ALWAYS ready to be proven wrong! That is part of being a "lifetime learner".

ScottB
02-09-2011, 01:04 PM
That's about where I stand - with a question I don't claim to have any final answers to. My gut says that in most cases I doubt that a thin shielding in an average size cavity will have any significant influence on tone. The information shared with Terry by the folks at Dimarzio and Lollar seem to agree with that. I'm willing to be surprised, but I just don't have the time to do any more tests to confirm or disprove anything right now.

I would tend to agree.

It would be nice to have the data, though. I will strive to play with this soon.

Zelja
02-09-2011, 02:29 PM
Just a question & maybe a warning about some of the shielding paints.

I have a Hamer Korina Jr, which does seem to have some type of shielding paint in the cavity which I fear is ineffective. When measuring the conductivity in the cavity, the meter doesn't read any continuity on the walls of the cavity at all. On the floor of the cavity it reads about 25 ohms at a distance of a few inches, - not the short circuit I would expect. The guitar also has a metal cover which is anodized I guess. Now taking a meter to the cover & I get an open circuit, as it is not bare metal I assume. There is a scratch on the bottom of the cover where it comes in contact with the cavity paint to electrically join the two. I guess the cover is OK because internally it is all metal & should do it's job.

So, it seems in this case the shielding paint is ineffective & I should re-shield the cavity, umless I am missing something. What do you guys think? Would I need to put copper tape on the metal control plate as well (I doubt it but...)?

burningyen
02-09-2011, 02:35 PM
I think Manlius is talking about going inside the single-coil pickups themselves and lining the pickup covers with shielding material, and I think Terry is talking only about shielding the body cavities of the guitar.

MarkF786
02-09-2011, 06:44 PM
I know of one respected boutique builder whose guitars sell in the $7500 range who is totally against shielding. I was kinda shocked and didn't agree with his opinion.

On any guitar I've owned with shielding, I've found it beneficial (without any tone loss that I could discern). And I've owned guitars by some of the same builders that lacked shielding in one small area (like around the toggle switch in the same position as a Les Paul) and even though the guitar was dual humbucker, I could hear some hum sneaking in.

thesjkexperienc
02-09-2011, 09:07 PM
Instead of shielding the entire cavity couldn't you just wrap the cloth wires in a "tube" of copper tape and ground that?

Does anyone know the minimum amount of shielding I would need to do to stop the dry static popping, coming through my amp, from having my hand go up and down the neck? This would be for a Tele style guitar.

AudioWonderland
02-10-2011, 04:41 AM
Instead of shielding the entire cavity couldn't you just wrap the cloth wires in a "tube" of copper tape and ground that?



Its not done with copper but this is done by some builders. They just use shielded two conductor wire to connect the components in the control cavity. The shielding of wiring is then put to ground.

The downside is that it does not protect the pots/switches/jacks in the circuit. This is often down for wiring between the control cavity and output jack for example where shielding the wire route would be difficult

Terry McInturff
02-10-2011, 07:27 AM
I think Manlius is talking about going inside the single-coil pickups themselves and lining the pickup covers with shielding material, and I think Terry is talking only about shielding the body cavities of the guitar.

This is correct regarding what I am discussing. I should have made that clearer in my OP. Im delighted by the level of discussion on this topic!

Chris Rice
02-10-2011, 08:36 AM
Be aware that the Stew-Mac paint will go bad if it sits in the can for a long time without being shaken or strirred.

I had this problem, too. It doesn't go bad, it just loses moisture and turns into paste.

I called Stew-Mac about it. They said I could revive the paint with tap water. I tried it, and it works fine. Just add water to the sludge until it returns to its original consistency.
Tap water works great. My jar was so far gone that it took a few days strapped into my wife's rock tumbler to mix it up enough. :bonk

Pscheoverdrive
02-10-2011, 10:43 AM
1) What is "blocking feedback"
2) The twisted shielding is not really the same. A faraday cage in total has much more mass and comes in close proximity to the pickups themselves. I would expect the likely hood of a faraday cage impacting things to be much higher.

I have always been of the understanding that any ferrous material that gets within the magnetic field of the pick will influence the eddie (sp) currents of that field. How much that impact things sonically I don't know. I would also think that there would be at least a little increase in capacitance. Do any of these combine into an audible difference? I don't know.

I think that since the noise consists of a lot of high end, once that's gone many people are perceiving that lost high end from the noise as a loss of high end in general.

When I said 'blocking feedback,' I was referencing the whole deal with wax-potting (or even shielding) pickups, which from what I understand, is done to 'block feedback.' Now that I think about it, I'm not really sure how wax-potting helps... Will be doing some research on that soon.

I bring up both topics because I'm suggesting that the 'treble-roll-off' that some users experience with shielding might just be what you suggested - that the high end loss is due to the loss of the high frequency noise, and not an actual change in pickup response.

So, I guess we're on the same page.




On another note, I think a few of you might enjoy reading this article from Bill Lawrence:

Maybe we should be using Downy instead of electric shields?! Keep reading! (http://www.billlawrence.com/Pages/Pickupology/External%20Interference.htm)

ScottB
02-10-2011, 10:58 AM
When I said 'blocking feedback,' I was referencing the whole deal with wax-potting (or even shielding) pickups, which from what I understand, is done to 'block feedback.' Now that I think about it, I'm not really sure how wax-potting helps... Will be doing some research on that soon.

I bring up both topics because I'm suggesting that the 'treble-roll-off' that some users experience with shielding might just be what you suggested - that the high end loss is due to the loss of the high frequency noise, and not an actual change in pickup response.

So, I guess we're on the same page.




On another note, I think a few of you might enjoy reading this article from Bill Lawrence:

Maybe we should be using Downy instead of electric shields?! Keep reading! (http://www.billlawrence.com/Pages/Pickupology/External%20Interference.htm)

Wax potting is for minimizing sympathetic vibrations of the coil wires and other parts, not shielding. These vibrations set up a feedback loop that causes that nasty squealing feedback, especially at high gain.

Pscheoverdrive
02-10-2011, 11:05 AM
Wax potting is for minimizing sympathetic vibrations of the coil wires and other parts, not shielding. These vibrations set up a feedback loop that causes that nasty squealing feedback, especially at high gain.

Thanks!

paulg
02-10-2011, 03:30 PM
If you're willing to go to the n-degree, sheilding may be worth it. But if it's not 100% then RF can get into your signal. So it seems to me that if you use single coils or open humbackers all is lost. What good is it to wrap the coil when RF goes through the plastic covers and bobbins? If you use a covered PAF with shielded cable, I can see that sheilding the control cavity could be benificial.

walterw
02-10-2011, 06:23 PM
are we kind of conflating three different things here?

there's the idea of shielding a control cavity or even a pickup cavity with non-magnetic material like copper, there's the idea of lining strat or p-90 pickup covers with that same material, and there's the idea of ferrous (magnetically attractive) metal within range of the pickup's magnetic field.

with the copper, since it's grounded, any hot lines next to it in theory create capacitive treble loss (a cap is a hot and a ground next to each other with a gap between).

i can't see that affecting the tone unless the shielding is right against the pickup coil like a humbucker cover would be. i suspect that single coils present more tonal change from this than 'buckers, just in the fact that 'bucker covers are ubiquitous (and i barely hear a difference) while shielded single-coil covers are rare. (edit: tele neck pickups! the cover totally mellows the tone, and by design.)

i remember reading that clapton shielded the insides of his strat pickup covers back in the '70s, accepting a bit of treble loss in exchange for noise reduction.

attractive metal anywhere near a pickup distorts the magnetic field and makes an obvious tonal difference, as any tele player can tell you.

John Coloccia
02-10-2011, 06:31 PM
Personally, my feeling is that of all the things that affect electric guitar tone, including ambient temperature/humidity (I can only guess this has something to do with the speaker cone....don't ask me, but I can hear it), shielding is somewhere down on my list next to plastic control knobs and strap buttons.s

I personally just don't hear it. Maybe my ears are just getting old.

dpm
02-10-2011, 07:53 PM
FWIW I've seen conductive paint lose it's conductivity over time too. I'm strictly a foil guy now, don't trust the paint.

Terry McInturff
02-10-2011, 08:17 PM
FWIW I've seen conductive paint lose it's conductivity over time too. I'm strictly a foil guy now, don't trust the paint.

I appreciate both your observation, and your having contributed it. Many thanks!

Over the past 24 hours, Ive tested 8 guitars that were painted with shielding paint in the years 1983- 1987. Every guitar's shielding showed strong, 100% conductivity...as new. All of the guitars were shielded with carbon-based paint.

Just a bit of current, tested stuff for everyone.

I suppose that different types of paint could "age" differently....and thus the conductivity could vary.

By two weeks from now, I will have tested an additional 14 guitars, painted with carbon-based shielding paint, and all of the guitars were made in the 1980's. If asked, I'll report my findings. That will make a total of 22 guitars that range in age from 22 to 28 years old.

dpm
02-10-2011, 08:44 PM
No problem Terry! I should expand on it though :)

For me the decision to ditch paint entirely was also a matter of time management. I could have continued with the paint, maybe tried extra coats etc. but considering that I'd then have to maybe do a few trials and test them over time, plus the fact that paint is kind of messy to work with, I just said 'screw it' and went back to foil. My control cavities are generally one depth so it's easy enough to apply foil to them without it getting too complicated.

What I have often found with painted cavities in the repair side of things is no continuity or a little resistance between test points. But that's in production guitars where corners are cut.

Rick Turner
02-10-2011, 09:21 PM
Believe Bill L. at your peril. The bit about eddy currents is total garbage. Anything conductive in a magnetic field that is being disturbed will have eddy current loss. It's higher in some materials than in others depending on conductivity, thickness, etc. These micro currents swirling around in the conductive material (why do you think many people took the covers off their humbuckers?) reduce the current generated in the coil, thus cutting signal. This is one of the reasons why Seth Lover was adamant about wanting nickel silver for humbucker covers...lower eddy current loss than with plated brass or copper covers.

I've gone to using plastic covers with carbon paint and a copper foil connection tab. I find the plastic covers are less microphonic, even with wax potted coils and then epoxy potted full assemblies, and the thin layer of paint has low eddy current loss.

I'm of the belief that too much shielding is barely enough provided you not have any significant capacitive losses, and that's a matter of cable dress inside your instrument cavities. I also try to minimize ground loops by lifting shields where practical and just having shield connected at one end with coax cables as long as it is not necessary for the shield to be carrying "signal low".

This is why some of the high end guitar cables are directional...they're actually "twinax" with signal hot and signal low (or ground) going down identical center conductors that are insulated from one another. Then the shield of the cable is only connected at the amplifier end.

Terry McInturff
02-10-2011, 09:43 PM
Believe Bill L. at your peril. The bit about eddy currents is total garbage. Anything conductive in a magnetic field that is being disturbed will have eddy current loss. It's higher in some materials than in others depending on conductivity, thickness, etc. These micro currents swirling around in the conductive material (why do you think many people took the covers off their humbuckers?) reduce the current generated in the coil, thus cutting signal. This is one of the reasons why Seth Lover was adamant about wanting nickel silver for humbucker covers...lower eddy current loss than with plated brass or copper covers.

I've gone to using plastic covers with carbon paint and a copper foil connection tab. I find the plastic covers are less microphonic, even with wax potted coils and then epoxy potted full assemblies, and the thin layer of paint has low eddy current loss.

I'm of the belief that too much shielding is barely enough provided you not have any significant capacitive losses, and that's a matter of cable dress inside your instrument cavities. I also try to minimize ground loops by lifting shields where practical and just having shield connected at one end with coax cables as long as it is not necessary for the shield to be carrying "signal low".

This is why some of the high end guitar cables are directional...they're actually "twinax" with signal hot and signal low (or ground) going down identical center conductors that are insulated from one another. Then the shield of the cable is only connected at the amplifier end.

If you all will pardon my language..."damn right". :)

Note the use of coax with a separate shield (usually with a drain wire).
This how, for instance, one would wire up a studio rack....and ultimately, the entire studio. The drain is always connected "down-stream". The drain/shield is separate and distinct from "hot" and "ground".

EMI and RF noise garbage works against the music. The fantastic vintage guitars sound great despite being an antenna for all of that. They would reveal all of their glory if a lot of that noise could be removed from the signal but...it is never right to mod a vintage guitar in such a way (IMO).

Trebor Renkluaf
02-13-2011, 05:03 PM
Guys,
Here's a cool a trick I learned a few years back - it might even have been here. You can buy adhesive backed copper foil sheet in 1' x 1' squares for just a couple of bucks at a stained glass supply store. These are great for shielding pickguards. It is 1.25 mil which is the same thickness as the copper shileding tape StewMac sells. Here's a pic with a strat pickguard (which I am about to shield btw) for size comparison.

http://i726.photobucket.com/albums/ww268/GuitArtMan/pickguard.jpg

I like this better than the rolls for pickguards, and it's cheaper than the aluminum shields that Callaham, Acme, etc. sell.
Bob

Ok, here's the completed pickguard.

http://i726.photobucket.com/albums/ww268/GuitArtMan/pickguard2.jpg

Husky
02-13-2011, 05:44 PM
I believe of course in proper shielding (not over shielding) but if I may Terry will elaborate a little on a couple of points. I haven't read all the pages so this might have been covered.
If you wrap the pickups with shielding copper or paint the covers with shielding paint you will knock off high end and output less with paint and it may be acceptable or even desired depending on the pickup design. Also copper is a better choice than aluminum tape. If the Aluminum shield on a pickguard is thick ala Fender it will alter the tone as well and you loose a little output, this is measurable in resonant peak especially. If the pickup wires are already shielded then there is no reason to shield the through holes. I know you know this Terry just thought I would save someone else from the extra work and mess. One good way to see if the guitar is well shielded is you should hear no extra buzz when you remove your hands from the guitar and strings (not touching any metal) Also .... good amp design should take care of the RF. Oh yeah, the paint does not have to be fully conductive and we use it we do 2 coats. When using carbon paint it must be stirred well. Funny story at a major manufacturer, One day they go to R&D to ask why the carbon paint is no longer conductive. Turns out production ran out of shielding paint and just went to the hardware store to buy some more flat black paint. LOL

T.L.
02-15-2011, 01:33 AM
In reality, shielding has little effect in single-coil equipped guitars, and pretty much no effect in humbucker equipped guitars, and is a waste of time. I guess it makes some players feel better psychologically though.

Look at the new EVH Wolfgang guitar. It has pretty much no shielding...

mody
02-15-2011, 07:05 AM
If the Aluminum shield on a pickguard is thick ala Fender it will alter the tone as well and you loose a little output, this is measurable in resonant peak especially.
:bow
Holy cow! My guitar now sounds like it should have, needless to say it's a more than subtle difference to me ears. You my dear Sir are a tone ninja.

AudioWonderland
02-15-2011, 10:16 AM
In reality, shielding has little effect in single-coil equipped guitars, and pretty much no effect in humbucker equipped guitars, and is a waste of time. I guess it makes some players feel better psychologically though.

Look at the new EVH Wolfgang guitar. It has pretty much no shielding...

:jo:facepalm:nuts:munch

Rick Turner
02-15-2011, 10:33 AM
T.L., you are showing an utter lack of understanding of the nature of the two sources of hum, buzz, and noise that get into guitar signals.

And to point to any unshielded production guitar as being worthy of our notice or as an example of something that works...when it doesn't...is absurd.

Do you know why fluorescent light fixtures hum?

Because they don't know the words...

T.L.
02-15-2011, 01:39 PM
T.L., you are showing an utter lack of understanding of the nature of the two sources of hum, buzz, and noise that get into guitar signals.

And to point to any unshielded production guitar as being worthy of our notice or as an example of something that works...when it doesn't...is absurd.

Do you know why fluorescent light fixtures hum?

Because they don't know the words...

I simply know from experience, that there is no difference after shielding a guitar than there was before doing so.

When I say "shielding" -- obviously, everything needs to be properly grounded. Most humbucker pickup cables are shielded (Belden), or co-ax, and wires from the volume pot to the switch, as well as from the switch to the output jack need to be shielded cable OR wires that are twisted around each other, but beyond that, all the copper foil and carbon-graphite shielding paint in the body cavities is doing a whole lot of nothing. Especially when used with humbuckers. It might make you feel warm & fuzzy inside knowing that your guitar has it, but I assure you there is no difference in the noise that your guitar picks up...

Terry McInturff
02-15-2011, 01:51 PM
I simply know from experience, that there is no difference after shielding a guitar than there was before doing so.

When I say "shielding" -- obviously, everything needs to be properly grounded. Most humbucker pickup cables are shielded (Belden), or co-ax, and wires from the volume pot to the switch, as well as from the switch to the output jack need to be shielded cable OR wires that are twisted around each other, but beyond that, all the copper foil and carbon-graphite shielding paint in the body cavities is doing a whole lot of nothing. Especially when used with humbuckers. It might make you feel warm & fuzzy inside knowing that your guitar has it, but I assure you there is no difference in the noise that your guitar picks up...

With the greatest possible respect, I disagree. I disagree completely with your statement that shielding...properly implemented.. has no effect upon the signal-to-noise ratio of the guitar. 34 years of experience with litterally thousands of shielded electric guitars has proven beyond doubt that there is indeed a reason to shield.

We disagree on this one, but many thanks for your comments which are always welcome in any thread I start! :)

Husky
02-15-2011, 02:03 PM
I simply know from experience, that there is no difference after shielding a guitar than there was before doing so.

When I say "shielding" -- obviously, everything needs to be properly grounded. Most humbucker pickup cables are shielded (Belden), or co-ax, and wires from the volume pot to the switch, as well as from the switch to the output jack need to be shielded cable OR wires that are twisted around each other, but beyond that, all the copper foil and carbon-graphite shielding paint in the body cavities is doing a whole lot of nothing. Especially when used with humbuckers. It might make you feel warm & fuzzy inside knowing that your guitar has it, but I assure you there is no difference in the noise that your guitar picks up...

Going to disagree as well, just the fact that a good shielding job will make removing you hands from metal on the guitar no different than hands on. Try an unshielded strat, there is a healthy buzz when you remove your hands from the ground path, this drives bass players nuts. It is a hell of a lot easier to shield the cavities than it is to remove all the unshielded wire and replace it with shielded cable. There is also static from some plastics on pickguards that pops and crackles getting in to the signal when your hands brush across them, those who have that body chemistry static know what I mean, shielding helps tremendously with that.. I find shielding helps the most with the high end garbage. 60 cycle does require more aggressive measures unless you are playing in the desert then it doesn't matter. Naturally if the cavities and pickguard are shielded there is no reason to shield the cables in side. One shield is enough. Your experiences on unshielded vs shielded could be biased depending on the rooms you play in and the exposure or lack of to interference.

Trebor Renkluaf
02-15-2011, 04:14 PM
that shielding...properly implemented..
There's the crux of the matter - properly implemented. Many times it is not.

T.L.
02-15-2011, 05:34 PM
This piques my curiosity, because in the 25 years that I have been playing guitar, I have NEVER played one that did not buzz when hands are taken off the strings or bridge. The typical electric guitar utilizes the player as the Ground. So what is grounding it when the player is not touching it? Simple copper shielding tape or conductive paint is not going to produce that quality, so you guys (John & Terry) obviously know something I don't (which is not difficult to believe)...

Husky
02-15-2011, 06:18 PM
This piques my curiosity, because in the 25 years that I have been playing guitar, I have NEVER played one that did not buzz when hands are taken off the strings or bridge. The typical electric guitar utilizes the player as the Ground. So what is grounding it when the player is not touching it? Simple copper shielding tape or conductive paint is not going to produce that quality, so you guys (John & Terry) obviously know something I don't (which is not difficult to believe)...

You should compare mine to an unshielded guitar, there is no noticeable buzz at all unlike all the unshielded guitars in the right environment. I also experienced this at Fender and since the early 80's. On the prototype J bass Deluxe when experimenting with a differential amplifier and dummy coil we found we HAD to shield 100% the cavities and with nickel silver paint or copper no less in order to fully eliminate any noise from CRT monitors and florescents, it worked but was too expensive for the project. The 60 cycle hum was taken care of by the Differential input and dummy coil, the high end buzz trash and interference went away with the shielding.
It (the shield cage) is being grounded to the amplifier and wall through your guitar cable ground, the shielded cavity protects the electronics and wiring. Your body is not required anymore to shield/ground the guitar. In fact EMG advises having no string ground at all. To say that shielding does not matter in a guitar???? Then you might as well use a speaker cable to plug in to your amplifiers input, tell me how that sounds.

Rick Turner
02-15-2011, 06:41 PM
The typical electric guitar absolutely does NOT use the player as ground, and a human body is a really crappy ground anyway as usually your body is not grounded. If you could get away with that you'd not even need a shielded cable. The only conditions under which that might work would be with an ultra low impedance pickup system on the instrument.

With the best shielded guitars, you get absolutely no difference in buzz level (a different issue than magnetically induced hum) with your hands on or off the strings; you shouldn't even get a little click when your body touches any grounded parts, strings, jack, knobs, switches, etc.

25 years with poorly shielded guitars does not make those guitars the only truth, and you shouldn't have to put up with this.

AudioWonderland
02-15-2011, 06:48 PM
I simply know from experience, that there is no difference after shielding a guitar than there was before doing so.

When I say "shielding" -- obviously, everything needs to be properly grounded. Most humbucker pickup cables are shielded (Belden), or co-ax, and wires from the volume pot to the switch, as well as from the switch to the output jack need to be shielded cable OR wires that are twisted around each other, but beyond that, all the copper foil and carbon-graphite shielding paint in the body cavities is doing a whole lot of nothing. Especially when used with humbuckers. It might make you feel warm & fuzzy inside knowing that your guitar has it, but I assure you there is no difference in the noise that your guitar picks up...

Save your assurances. They are not worth the paper they are printed on. Its not speculation or hearsay. Its physics. It works.

Terry McInturff
02-15-2011, 07:36 PM
There's the crux of the matter - properly implemented. Many times it is not.

This is true. But can you consider a builder who tries to do that.. incorrectly... a "world-class" expert on the subject of building electric guitars?

C'mon, I say...we are talking about electric guitars for goodness sake...is it to much to expect, as a matter of course, good work in these areas after all of these decades?

An egocentric post on my part that I stand behind nonetheless.

T.L.
02-15-2011, 07:36 PM
Save your assurances. They are not worth the paper they are printed on. Its not speculation or hearsay. Its physics. It works.

Really? On what guitars? I've never played a Suhr, but everything I HAVE played on (MANY brands), whether shielded or not, buzzed from Florescent lighting, CRT monitors, standing too close to a guitar amp (obviously the transformer), etc. It made no difference whether the guitar had shielded cavities or not. Every electric guitar I own has conductive paint in the cavities (and my Strat has foil on the back of the pickguard), and they all pick up the same level of noise as guitars I have played with no body cavity shielding. My "assurances" were based strictly on my own personal experiences, not "speculation or hearsay"...

T.L.
02-15-2011, 07:38 PM
The typical electric guitar absolutely does NOT use the player as ground, and a human body is a really crappy ground anyway as usually your body is not grounded. If you could get away with that you'd not even need a shielded cable. The only conditions under which that might work would be with an ultra low impedance pickup system on the instrument.

With the best shielded guitars, you get absolutely no difference in buzz level (a different issue than magnetically induced hum) with your hands on or off the strings; you shouldn't even get a little click when your body touches any grounded parts, strings, jack, knobs, switches, etc.

25 years with poorly shielded guitars does not make those guitars the only truth, and you shouldn't have to put up with this.

Well, then why has EVERY guitar I've ever played gotten quiet when I touched the strings or the bridge? Does anyone have an explanation for that?...

T.L.
02-15-2011, 07:48 PM
To say that shielding does not matter in a guitar???? Then you might as well use a speaker cable to plug in to your amplifier, tell me how that sounds.

I probably should have been more clear and used different wording to express the point I was trying to make. I was referring strictly to the body cavity "shielding" with copper/aluminum tape/foil, or carbon-graphite paint.

I am aware that despite my experience, you have even MORE, and that you have devised things such as a shielding system to eliminate 60-cycle hum from single coil pickups (although that is not the type of "noise" I was referring to), and now I'm being told that you have eliminated the need to touch the strings or bridge (and I believe you) to make the "buzz" stop (by the way; does this include when the guitar is plugged into the overdrive channel of an amp?). That impresses me. All I can deduce from this is that probably 90% of the major guitar manufacturers do not implement such technology.

By the way, I had a guitar that came with EMGs and a Floyd Rose that had no ground wire attached to the spring claw. I swapped out the EMGs for a passive set of pickups, and soldered a ground wire to it. I figured that the lack of a ground wire was specific to the EMG design...

Husky
02-15-2011, 08:11 PM
Well, then why has EVERY guitar I've ever played gotten quiet when I touched the strings or the bridge? Does anyone have an explanation for that?...

Because they couldn't have had complete proper shielding.
Trust me. I have built thousands of guitars that don't buzz or hum. It is a pet peeve if you can't tell by the SSC system.

Husky
02-15-2011, 08:23 PM
You are right on a few points
Easily 90% of the guitars sold don't have proper shielding of the cavities.
Even in reference to the cavities that is the first source of high frequency interference and where it needs to be stopped. Think of it like a window covered with pitch black paint, you can't leave one area open or the sun will still light the room up. Unfortunately there is no totally non tone altering method to keep the noise from entering the top of the pickups but shielding the cavities and any non shielded exposed wires including the input jack of a strat will certainly get you quiet with hands off and will have less issues with buzz noise than if not. Plus .... As a test I see if I can take my hand off the strings and hear extra buzz, without shielding it is atrocious with shielding barely noticeable if at all even with pedals on. I've been doing full shielding experiments since the 70's. When bass players would complain. Don't know why but they love to take their hands off the strings.. You also have the newer issue of coated strings on guitars and basses since you have no string ground anyway when touching the wound strings.

I probably should have been more clear and used different wording to express the point I was trying to make. I was referring strictly to the body cavity "shielding" with copper/aluminum tape/foil, or carbon-graphite paint.

I am aware that despite my experience, you have even MORE, and that you have devised things such as a shielding system to eliminate 60-cycle hum from single coil pickups (although that is not the type of "noise" I was referring to), and now I'm being told that you have eliminated the need to touch the strings or bridge (and I believe you) to make the "buzz" stop (by the way; does this include when the guitar is plugged into the overdrive channel of an amp?). That impresses me. All I can deduce from this is that probably 90% of the major guitar manufacturers do not implement such technology.

By the way, I had a guitar that came with EMGs and a Floyd Rose that had no ground wire attached to the spring claw. I swapped out the EMGs for a passive set of pickups, and soldered a ground wire to it. I figured that the lack of a ground wire was specific to the EMG design...

T.L.
02-15-2011, 10:34 PM
Yet another reason (among many) that your guitars are so highly regarded, John.

One of these days, I'll have one of my own. Not this year though...

Terry McInturff
02-15-2011, 11:20 PM
Yet another reason (among many) that your guitars are so highly regarded, John.

One of these days, I'll have one of my own. Not this year though...

C'mon! :) You can find a way to get a Suhr this year...

AND BUY ONE NEW :)

beNsteR
02-15-2011, 11:38 PM
Try an unshielded strat, there is a healthy buzz when you remove your hands from the ground path, this drives bass players nuts.

LOL @ this! :rotflmao:bow

Rick Turner
02-16-2011, 12:00 AM
How come it is that the most experienced guitar makers here all agree 100% on this? Among John, Terry, and myself, I'll bet we've had well over 20,000 electric guitars and basses in our hands...plugged in and buzzing...or not...and we know why, and we know how to fix it, and we're laying the answers out right here.

It kind of blows my mind how little respect there is on the Internet for real world experience. Anybody with a monitor and keyboard is an expert in Cyberspace...

NOT...

drezdin
02-16-2011, 04:33 AM
Mr. Turner your comments are very much appreciated here. I'm always in these threads learning from you guys.
I have a lot of respect for the luthiers on tgp. I just prefer to listen and learn. I'm sure there are many here who would agree with me.

Ahess86
02-16-2011, 09:13 AM
Forgive me if this was discussed earlier, but I'm curious how this plays out in a guitar that's rear-routed w/ top-loaded pickups. Seems like the shield-able area is significantly reduced since there is no pickguard.

Chris Rice
02-16-2011, 09:39 AM
Shield the pickup cavities and the control cavity (don't forget the backplate). Either shield the wire channels with Terry's pipe cleaner trick or use shielded cable (run a ground into the pickup cavities to ground the shielding tape or paint). I don't find the extra shielding of a large pickguard to do anything extra.

Trebor Renkluaf
02-16-2011, 10:20 AM
How come it is that the most experienced guitar makers here all agree 100% on this? Among John, Terry, and myself, I'll bet we've had well over 20,000 electric guitars and basses in our hands...plugged in and buzzing...or not...and we know why, and we know how to fix it, and we're laying the answers out right here.

It kind of blows my mind how little respect there is on the Internet for real world experience. Anybody with a monitor and keyboard is an expert in Cyberspace...

NOT...
Welcome to the internet. Want another great discussion? Just bring up fingerboard treatments. I honestly would like to see a scientific study done on fingerboard treatments (for rosewood/ebony boards) and how they affect the stability, strength, resistance to swelling/shrinking/cracking, resistance to wear, ease of repairs (refret, planing, etc.), feel (oily, waxy, smooth, slick, sticky, etc.) etc., etc., etc.

Terry McInturff
02-16-2011, 10:23 AM
How come it is that the most experienced guitar makers here all agree 100% on this? Among John, Terry, and myself, I'll bet we've had well over 20,000 electric guitars and basses in our hands...plugged in and buzzing...or not...and we know why, and we know how to fix it, and we're laying the answers out right here.

It kind of blows my mind how little respect there is on the Internet for real world experience. Anybody with a monitor and keyboard is an expert in Cyberspace...

NOT...

I can appreciate your dismay...perhaps I have just gotten used to it. However, I welcome all conversation that is expressed in an adult and polite manner. "Doubting Thomas'" can very often open up the conversation, and often enough I find that I have not explained something satisfactorily in the first place.

Also, there is the matter of the "Silent Majority". It is helpful to remember that quite often, more read and do not post comments. The vast majority of TCM owners do not visit chat rooms or post on them for example.

Rick, I think that you are being conservative in your estimate of how many guitars Rick, John, and Terry have plugged in and inspected; I'd bet that the total would actually be in the 60,000 range. :)

During one 10 month period in the early 1990's, for example, I was working in a production environment and handled/setup approx 2000 guitars...all of which were shielded...and it was very easy to tell when the shielding had not been done right (tho the vast majority were)

Tidewater Custom Shop
02-16-2011, 11:00 AM
Also, there is the matter of the "Silent Majority". It is helpful to remember that quite often, more read and do not post comments.

At the time of this posting, there were 100 comments and 3100 views. Like me, I think most of the silent majority learn by reading these type threads. I commented long ago in this thread (post #17) that I applied shielding techniques that I learned from the internet to my Strat with great success - it is as quiet as it can be.

There will always be Doubting Thomas' whose experience is different (for whatever reason) than what is being presented.

RevZone
02-16-2011, 01:15 PM
Yep, normally I just read and learn. And I'm really grateful to all who share their knowledge! However, not believing everything I read, I did my own tests using StewMac shielding paint and grounding. All my guitars now use shielding.

Rick Turner
02-16-2011, 03:27 PM
And why limit shielding to non-vintage guitars if those guitars are to be used as serious musical tools and not as religious sculptures to be hidden in musty cases or hung in glass cases?

Vintage guitars can be improved, made better than new, and if you're talking Fenders and Gibsons, these are not precious luthier-made items; they were the result of industrial guitar making. That they were not shielded better is, as I see it, a matter of cost cutting, not engineering, though some...like a number of vintages of Les Pauls, 335s, and some of Leo's later guitars, were pretty well done.

The mania for originality has gone too far.

You don't drive a vintage car on vintage rubber.

John Coloccia
02-16-2011, 04:22 PM
Tip: how to paint internal wire holes
Pipe cleaners make a good "brush" for this.



I don't know how I missed this before. Great tip, Terry!

T.L.
02-16-2011, 10:59 PM
So, exactly what are the majority of major guitar manufacturers doing wrong in their attempts at shielding? Like I said, I have NEVER played a guitar that did not require hands touching the strings or bridge to quiet the "buzz" when the volume pot is turned up. Yet most of these guitars have the conductive shielding paint in the cavities. Or foil on the back of pickguard-equipped guitars...

Husky
02-16-2011, 11:23 PM
So, exactly what are the majority of major guitar manufacturers doing wrong in their attempts at shielding? Like I said, I have NEVER played a guitar that did not require hands touching the strings or bridge to quiet the "buzz" when the volume pot is turned up. Yet most of these guitars have the conductive shielding paint in the cavities. Or foil on the back of pickguard-equipped guitars...
To little paint is one error, very light coat of paint I witnessed at one large company including one time they were using flat black paint instead of shielding by mistake. Sometimes they dont tie the shield to ground. Some companies also just shield the pickguard and don't bother with anything else. Some companies don't shield at all My newish Les Paul and SG are not shielded at all.
I don't understand where you are going with this, I thought we covered it.

Pscheoverdrive
02-17-2011, 12:19 AM
Few people like to read whole threads before adding their $.0001 on this board, I've noticed... Then again, it is a large and fast-moving board, with lots of unhelpful one-line posts, so I guess it's understandable, but still annoying at times.

T.L.
02-17-2011, 04:59 PM
To little paint is one error, very light coat of paint I witnessed at one large company including one time they were using flat black paint instead of shielding by mistake. Sometimes they dont tie the shield to ground. Some companies also just shield the pickguard and don't bother with anything else. Some companies don't shield at all My newish Les Paul and SG are not shielded at all.
I don't understand where you are going with this, I thought we covered it.

'Sorry, John. I guess I was just looking for more specifics. If so many guitar manufacturers do not know how to properly shield a guitar (and it certainly appears that way), then it must be some great mystery that only you and a handful of others know the secret to. 'Wasn't trying to beat a dead horse...

Husky
02-17-2011, 05:36 PM
'Sorry, John. I guess I was just looking for more specifics. If so many guitar manufacturers do not know how to properly shield a guitar (and it certainly appears that way), then it must be some great mystery that only you and a handful of others know the secret to. 'Wasn't trying to beat a dead horse...
Fair enough, this is about all I can tell you in a paragraph.
Not really mystical at all, just usually not the right person in charge. Production and profits can be the greater issue with larger companies. The proof is in two personal experiences for instance..... once who knows how many guitar were shipped with flat black paint instead of carbon paint. Mainly because someone in assembly didn't know the purpose of the paint and when they ran out the hardware store was easy and close. Another funny was on a tele a .005uf cap was called for across the volume pot, not knowing the difference .05uf caps were installed making the Volume work like a switch. Nobody could figure it out cause they didn't know what the difference was between 503 and 502 makings on the cap, they were in the wrong drawer. Some don't realize that the conductive solids in the paint settle, if you don't stir the paint you get poor results, also a double coat is important. This takes time unless you use a hair dryer (inside tip). The shielding paint comes in a 5 gallon container, people pour it off in to gallons or quarts. If you don't completely stir that 5gallon pail the conductive properties on the first 3 gallons will be shit. These are just a few of the many issues that can be overlooked. This is the case for having people who really know what they are doing with all aspects do the actual assembly as opposed to an assembly line who only know that the paint is black and the capacitor is "the brown one". I also know of a few excellent builders who just don't believe it is an issue, the noise doesn't bother them and if hands on the strings stops it then whats the problem.....There are other gross mistakes on shielded guitars but it would have to be diagnosed on an individual basis. Some guitar companies look at electronics as being overly simple when there are many things to consider that are not obvious on the surface. You show me one guitar and I'll tell you what is wrong is about the only way I could address your question here. Or to say ...."I have been wondering that all my life " ! After all if you know why I got in to this business it is because I felt let down by the product I was purchasing (the short story). If you avoid double grounding, ground loops, use good shielding paint with a double coat or nickel silver print that is well stirred, have it performed by someone who really understands electronics and solders well you will apparently hear something you have not heard before. Of course there will still be noise, the object is to get rid of it as much as possible if it bothers you, it always bothered me. I'd say when you have it down to a point where you can remove your hands from the strings and not hear extra buzz or very very minimal you have a good and correct shielding job. Otherwise it is probably just a shielded pickguard or not executed correctly.

walterw
02-17-2011, 06:45 PM
good stuff, but i have to ask about this:If you avoid double grounding, ground loops,...
like i asked terry, how can you have ground loops in a guitar when the only available ground potential is the sleeve of the cable?

John Coloccia
02-17-2011, 07:56 PM
You can have ground loops because you have varying potentials due to conductors with non-zero resistances. The only reason typical guitar wiring gets away with it is that the currents are teeny tiny so you only get minor differences in ground potential, and with good shielding you don't pick up enough EMF to really matter. Ideally, all of the guitar components would be grounded in a star topology, and the shielding would not contact any of the component grounds, but only the ground at the center of the star (usually the jack).

Even though the guitar circuit is "passive" in the sense that there are no gain components like op-amps involved, the pickup/strings are an AC supply. If there's anyway for any of that signal to get to output jack through multiple paths with varying resistances, you have a ground loop. Whether that's significant or not can be debated. There's enough guitars out there wired like this that don't hum to kingdom come that it's probably not a big deal for whatever reason :)

Anyhow, that's just my take on it coming at it as an engineer. Yeah, maybe a lot of the wiring isn't ideal, but we're not trying to make lab measurements :D

Husky
02-17-2011, 08:13 PM
You can have ground loops because you have varying potentials due to conductors with non-zero resistances. The only reason typical guitar wiring gets away with it is that the currents are teeny tiny so you only get minor differences in ground potential, and with good shielding you don't pick up enough EMF to really matter. Ideally, all of the guitar components would be grounded in a star topology, and the shielding would not contact any of the component grounds, but only the ground at the center of the star (usually the jack).

Even though the guitar circuit is "passive" in the sense that there are no gain components like op-amps involved, the pickup/strings are an AC supply. If there's anyway for any of that signal to get to output jack through multiple paths with varying resistances, you have a ground loop. Whether that's significant or not can be debated. There's enough guitars out there wired like this that don't hum to kingdom come that it's probably not a big deal for whatever reason :)

Exactly, usually it is no big deal for instance to have a shield that makes a ground as well as the the pots connected with a wire but technically it is a loop and these days I avoid it by preventing the pot from touching the shield and connect the grounds with wires so you are not dependent on the shield for your tone control to work for instance. You could say it all has to terminate through the cable but the wiring in an amp terminates at the wall. Again much more sensitive especially due to the amplification. I learned my lesson in the early 80's, a customer had a rewired Les Paul where a ground buss wire connected the back of the 4 pots and then back to the first, so it was a complete loop terminated at the start. The guitar had terrible RF and radio station pickup even on my bench thru a clean amp. I clipped the complete loop to make a U instead of an O and bamm the RF went away instantly as I clipped it. Lesson learned, it does matter in guitars as well.

Rick Turner
02-18-2011, 09:55 AM
I heartily endorse all that John is saying here.

As one who makes a lot of active instruments, I can tell you that "star grounding" and eliminating ground loops is even more important when you have stages of amplification on-board. You'd be amazed at what seemingly insignificant details make a difference.

I do not insulate pot bushings and cans nor switches from shield, but I'm careful about how ground wires are connected, and I lift shield where appropriate on coax cables on the "up stream" end.

Terry McInturff
02-18-2011, 10:13 AM
John and Rick:

BINGO BINGO BINGO BINGO !!!!!!

T.L.
02-19-2011, 10:30 AM
Thanks John. I apreciate you taking the time to go into all of that.

My guitars are pretty dang quite WHEN I'm touching the strings. It never bothered me that I had to be touching the strings, but I always thought there was no choice in the matter, and that it was just the nature of electric guitar. Thanks to you, I have learned something.

Do you (or anyone else here) have any idea why the $3000 EVH Wolfgang guitar has no shielding in the electronics cavities? Ed says that it's to "allow the wood to breathe and age" (as if that's going to help tone), but that seems so bogus to me...

Rick Turner
02-19-2011, 11:24 AM
T.L., that's bogus. Just because EVH is a great guitar player does not mean that he is an authority on everything to do with guitars. There are myths that roll off the tongue and would seem to have the weight of the authority of the ages that are total bullshit. That's one of them.

Husky
02-19-2011, 12:04 PM
Yeah everything about paint not letting the guitar "breath" is bull.
People argue lacquer lets the guitar breath and catalysts paints like urethanes don't.
If this was true a neck with acrylic urethane would never need adjusting ever. Far from the case.

Evan Gluck
02-19-2011, 12:46 PM
"If this was true a neck with acrylic urethane would never need adjusting ever. Far from the case."
Thank you John, been saying that for years.

Gordon
02-19-2011, 01:09 PM
I don't think you can say that shielding will not have an affect on the overall tone of your guitar. It just isn't the case. If the pickups are included in this and shielded, there will be a change in the treble response of the pickup...

It is a pretty easy experiment, take a single coil and drop it in a guitar and play it and listen. Then shield and ground the pickup, drop it back in and play it and you will hear quite a bit of difference. It isn't necessarily good or bad, but it IS different.

So you can't say that shielding is completely non-invasive to the tone on an instrument, as long as the pickups are part of the shielding process.

This statement is 100% correct. The reason for the very slight roll-off of high frequencies is because with shielding, the pickup coil is now capacitively coupled to ground. The degree of coupling is inversely proportional to the distance between the coil and the shielding. This occurs with pickups that have a coil that is not encased in metal, like a Strat. The electronic equivalent is that of a small value capacitor from hot to ground. Some people can hear the difference, some can't.

Husky
02-19-2011, 01:34 PM
This is only the case when you directly shield the pickup. And even so there is a big trick to minimize that. As far as shielding the cavity with carbo paint it us not measurable where the thick aluminum shield on the pickguard is.

Gordon
02-19-2011, 02:38 PM
Here's a quick test. I put a Strat pup on a little stack of cardboard and surrounded it with some aluminum foil.

http://i97.photobucket.com/albums/l209/Gordon_022/permanent%20pics%20on%20threads/IMG_0953.jpg

The pickup is considerably farther from the foil than it would be from the shielding in a vintage routed Strat so I would expect a higher reading on the meter if the pickup was installed in a shielded guitar, maybe 65-70 pf.

Husky
02-19-2011, 03:18 PM
Here's a quick test. I put a Strat pup on a little stack of cardboard and surrounded it with some aluminum foil.



The pickup is considerably farther from the foil than it would be from the shielding in a vintage routed Strat so I would expect a higher reading on the meter if the pickup was installed in a shielded guitar, maybe 65-70 pf.

I'll try this in a carbon painted cavity on Monday. I trust you 0'd out the meter? What does the measurement look like with the pickup off the foil?
Aluminum isn't a good choice for shielding either, I believe it is more to do with interfering with the magnetic field as opposed to capacitance.
Lets not forget you probably have about 80 - 200 pF capacitance in the coil and the cable capacitance of about 300 - 1,000 pF as well.
You should raise the pickup up off the foil if you want to mimic the proximity to the bottom of the cavity.
IF you really want to be spooked about 20pf then use shielded cable to the pickups and only shield the control cavity. You also better put a buffer in the guitar to combat all the capacitance in your cable and any effects that are being plugged in to. The flip side is it is that very capacitance and distributed capacitance that gives you sweet overdrive tones. Guitar sound very clinical when you put a buffer in the guitar or use ultra low capacitance cable.

I think what I would do to more correctly mimic what will happen is terminate the coil with a 250K resistor if you dont terminate it with a full set of controls (better), then compare the capacitance across the output of the loaded controls or preferable the end of the guitar cable since that is what the amp will see, with coil on and off a carbon painted cavity.

Gordon
02-19-2011, 04:31 PM
I'll try this in a carbon painted cavity on Monday. I trust you 0'd out the meter? What does the measurement look like with the pickup off the foil?
Aluminum isn't a good choice for shielding either, I believe it is more to do with interfering with the magnetic field as opposed to capacitance.
Lets not forget you probably have about 80 - 200 pF capacitance in the coil and the cable capacitance of about 300 - 1,000 pF as well.
You should raise the pickup up off the foil if you want to mimic the proximity to the bottom of the cavity.
IF you really want to be spooked about 20pf then use shielded cable to the pickups and only shield the control cavity. You also better put a buffer in the guitar to combat all the capacitance in your cable and any effects that are being plugged in to. The flip side is it is that very capacitance and distributed capacitance that gives you sweet overdrive tones. Guitar sound very clinical when you put a buffer in the guitar or use ultra low capacitance cable.

I think what I would do to more correctly mimic what will happen is terminate the coil with a 250K resistor if you dont terminate it with a full set of controls (better), then compare the capacitance across the output of the loaded controls or preferable the end of the guitar cable since that is what the amp will see, with coil on and off a carbon painted cavity.

Yes, I would have done the test on a guitar as well, but don't own one. Yes, the meter was zero'd prior to testing. Yes, the pup is sitting on top of a 1/2" stack of cardboard. I can move the pup away from the foil and get down to 1 or 2 pf. I don't think it's as much interference with the magnetic field as you may. If that was the case, I should have heard no effect when I disconnected the wire that went to the shielding on a Strat that I used to own, since if the effect was purely magnetic it wouldn't matter if the shielding was grounded or not. The change was more like cutting off four or five feet of guitar cable. BTW, I use low capacitance cable and only have about 300pf from the guitar to the amp so a change of 50-100pf is quite noticeable.

Husky
02-19-2011, 04:45 PM
Yes, I would have done the test on a guitar as well, but don't own one. Yes, the meter was zero'd prior to testing. Yes, the pup is sitting on top of a 1/2" stack of cardboard. I can move the pup away from the foil and get down to 1 or 2 pf. I don't think it's as much interference with the magnetic field as you may. If that was the case, I should have heard no effect when I disconnected the wire that went to the shielding on a Strat that I used to own, since if the effect was purely magnetic it wouldn't matter if the shielding was grounded or not. The change was more like cutting off four or five feet of guitar cable. BTW, I use low capacitance cable and only have about 300pf from the guitar to the amp so a change of 50-100pf is quite noticeable.

My experience at Fender while lowering a pickguard in to an Aluminum body was the inductance dropped away big time (sounded like ass too) easily seen on the LCR meter, maybe having to do with Eddie currents or some mumbo jumbo or Lenz's law but it was a terrible experience and it took a while for us to figure out why the pickups sounded like ass (it wasn't the pickups) and we read no change in capacitance. Besides high end the pickups lost a lot of bass. That could not be explained by capacitance.
http://www.youtube.com/watch?v=WHCwgc_xs3s&feature=related
I still think you need to hook the pickup up to the full control set at the very least to get a fair reading, right now you have stray capacitance with that ground lead floating in the air. The circuit needs to be terminated, you have a tone control cap of 47n that is always effectively in circuit being tied to ground via 250K as well as a 250K volume pot. Terminate the circuit correctly with a real world situation and then try. If I can find some time I'll try it on Monday and post what I get. You can always add a little presence or brightness even if you do hear the effect but there is no amplifier knob to reduce static, noise and interference.

walterw
02-19-2011, 08:07 PM
I learned my lesson in the early 80's, a customer had a rewired Les Paul where a ground buss wire connected the back of the 4 pots and then back to the first, so it was a complete loop terminated at the start. The guitar had terrible RF and radio station pickup even on my bench thru a clean amp. I clipped the complete loop to make a U instead of an O and bamm the RF went away instantly as I clipped it.
my mind, she is blown :eek:

chase
02-20-2011, 06:51 AM
I'm very happy to see this kind of thoughtful, scientific approach here. Too often guitar discussions just end up being about voodoo without any attempt to substantiate the claims being made. This discussion could have become an endless debate about the benefits or drawbacks of shielding, but instead it's evolved into something much more worthwhile. Thanks all.

I still think you need to hook the pickup up to the full control set at the very least to get a fair reading, right now you have stray capacitance with that ground lead floating in the air. The circuit needs to be terminated, you have a tone control cap of 47n that is always effectively in circuit being tied to ground via 250K as well as a 250K volume pot. Terminate the circuit correctly with a real world situation and then try. If I can find some time I'll try it on Monday and post what I get. You can always add a little presence or brightness even if you do hear the effect but there is no amplifier knob to reduce static, noise and interference.

jzucker
02-20-2011, 06:05 PM
can't agree that it doesn't effect tone. It has been shown that shielding acts as a small value capacitor, bleeding off high frequencies. Whether that's a deal breaker between shielded and unshielded is debatable but there's no question that it *DOES* effect tone.

Husky
02-20-2011, 07:05 PM
can't agree that it doesn't effect tone. It has been shown that shielding acts as a small value capacitor, bleeding off high frequencies. Whether that's a deal breaker between shielded and unshielded is debatable but there's no question that it *DOES* effect tone.

To what degree is the question and
Is it a detriment
Absolutely everything changes tone. Right down to the pick you use and how you play and all the capacitance in the amplifier you plug in to. It also has Not been proven (with any evidence i have seen) that there is any real world capacitance using carbon paint in a cavity with a proper loaded circuit if the pickups are not directly shielded. It is also not what I was talking about when lowering a pickguard in to a non magnetic aluminum guitar body and watching the inductance drop. That is not explained by capacitance. I don't think anyone could prove that shielding only a control cavity is going to change the tone. It is all about the implementation when it comes to shielding without changing the tone in an undesirable way.

Arcane-Inc
02-20-2011, 11:33 PM
I finally had a chance to do some pix and tests, (Tele Pickups because that is what I am working on at the moment). This relates to some of the things being discussed here and some other subjects not necessarily related to shielding. Of interesting note is how different metals have an affect or no affect on these types of measurements.

A few things I think we can agree on:
Putting a cover on a pickup changes the tone and it can be heard.
Putting a base plate on a pickup changes the tone and it can be heard.

Tele Bridge pickup
Inductance:
Tele Bridge pickup no base plate, no screws, not mounted in a bridge: Inductance 3.201
Tele Bridge pickup with base plate mounted and no screws: 3.434
Tele Bridge pickup with base plate mounted and screws: 3.452
Tele Bridge pickup with base plate mounted, screws and in a bridge: 3.463

Gauss:
Tele Bridge pickup no base plate, no screws, not mounted in a bridge: 16.7
Tele Bridge pickup with base plate mounted and no screws: 19.7

Tele neck pickups
Inductance:
Tele Neck pickup no cover: 2.609
Tele Neck pickup with cover: 2.610 Almost No change

Gauss:
Tele Neck pickup no cover: 20.3
Tele Neck pickup with cover: 18.2

http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05645.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05646.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05647.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05648.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05643.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05644.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05632.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05634.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05640.jpg
http://i269.photobucket.com/albums/jj62/ArcaneInc/Inductance%20gauss/DSC05641.jpg

dead of night
02-21-2011, 10:25 AM
I have a Collings 290 that makes a lot of noise when I remove my hands from the strings. I sure would love to have that problem solved because I don't like it. Does anyone know what Collings' stand on this issue is?

LooseEelBalls
02-21-2011, 10:34 AM
Fact.
Any Questions?

Husky
02-21-2011, 12:55 PM
Nobody is arguing that magnetic metals affect the inductance or Gauss, but to get a more accurate Gauss reading on the tele neck pickup you should read the Gauss from the bottom to eliminate the air gap. Also are you using standard brass covers or the more transparent solution of nickel silver? Also, run resonant peak sweeps on the pickups in and out of circuit for some more very interesting results.

Back to capacitance..
You can NOT measure capacitance of a pickup and expect any real information unless you put it in to the circuit it lives in, loaded with a tone control 5way and wiring. Capacitance you measure in free air not under load could be stray capacitance. I tried the foil (copper) under the pickup and around the sides accurately approximating the cavity size of a single coil and also read approximately 10pf of capacitance to copper foil.

However...In the real world situation under load I just measure the capacitance at the jack, fully loaded pickguard in and out of a double shielded carbon conductive painted cavity. The results on my Extech 380193 was (9.839nf) 9,839pf with the pickguard off the guitar and 6" above the cavity. This is with 1 Volume control, one tone control 47n and all wired up with CTS controls on 10. I could not measure ANY difference at the output jack with the pickguard in or out of the control cavity and this is not a universal route so it hugs the pickup but it IS with Carbon conductive paint. Your mileage may vary with Copper or Aluminum. Even if there were 15pf of capacitance that would be .15% of change, pretty amazing to really hear that, but then again I couldn't even read that or anything repeatable with the carbon painted cavity in a guitar. So at least the way I shield the capacitance is a non issue. I do not shield the pickup directly or covers, that I know will change things.
Any Questions?

T.L.
02-22-2011, 01:13 AM
I'm very happy to see this kind of thoughtful, scientific approach here. Too often guitar discussions just end up being about voodoo without any attempt to substantiate the claims being made. This discussion could have become an endless debate about the benefits or drawbacks of shielding, but instead it's evolved into something much more worthwhile. Thanks all.

Hey, are you Mr. "Wild Stringdom"?...

Tubevalvemaniac
02-22-2011, 05:32 AM
From my experience with 20+ guitars, no point in shielding.
Pickup choice, good wire and cables are different story.

chase
02-22-2011, 12:33 PM
Hey, are you Mr. "Wild Stringdom"?...

I'm not, no - what's the reference?

chase
02-22-2011, 12:38 PM
From my experience with 20+ guitars, no point in shielding.
Pickup choice, good wire and cables are different story.

Well, your experience with 20+ guitars certainly trumps John Suhr, Rick Turner, and Terry McInturff's experience with 20,000-60,000.

http://i67.photobucket.com/albums/h314/robotchas/facepalm1.jpg

...and we're right back where we started.

pickaguitar
02-22-2011, 12:46 PM
My strat is shielded and does/did pretty good...until recently. I think there is a short (pot touching the shielding and makes the guitar cut out) I haven't opened it up yet

Trebor Renkluaf
02-22-2011, 02:25 PM
My strat is shielded and does/did pretty good...until recently. I think there is a short (pot touching the shielding and makes the guitar cut out) I haven't opened it up yet
The casing of the pot should touch the shield.

Husky
02-22-2011, 02:27 PM
The casing of the pot should touch the shield.
Maybe he means one of the hot leads of the volume or tone pot is touching and shorting out against the shield on the side wall, this isnt the fault of or has anything to do with the shielding being a tone issue though. Also ideally there should only be one contact for the shield and grounds.

pickaguitar
02-22-2011, 02:31 PM
Maybe he means one of the hot leads of the volume or tone pot is touching and shorting out against the shield on the side wall, this isnt the fault of or has anything to do with the shielding being a tone issue though. Also ideally there should only be one contact for the shield and grounds.
yes this ^

I had a tech find it before and fix...but it's back again lol

Terry McInturff
02-22-2011, 02:51 PM
Who would have thought that this would have been one of the busiest threads Ive ever started?

Many thanks to everyone!

dead of night
02-22-2011, 03:07 PM
Who would have thought that this would have been one of the busiest threads Ive ever started?

Many thanks to everyone!
That's because the last one to post gets a free McInturff Carolina Custom.

Husky
02-22-2011, 03:10 PM
Who would have thought that this would have been one of the busiest threads Ive ever started?

Many thanks to everyone!

That is cause I butted in :rotflmao:rotflmao
:sarcasm
Wheres my guitar ! lock this damn thread

anyone
02-22-2011, 03:12 PM
IBTL

Structo
02-22-2011, 03:36 PM
Shielding is a hoax, it never happened. :bonk

Rick Turner
02-22-2011, 10:53 PM
John, my only question for you is, "Can I buy you a couple of beers some evening away from total madness?" I really enjoyed meeting you at NAMM, and would love to share war stories...

Terry McInturff
02-23-2011, 06:54 AM
John, my only question for you is, "Can I buy you a couple of beers some evening away from total madness?" I really enjoyed meeting you at NAMM, and would love to share war stories...

Just so I can be there "in spirits" I shall FedEx you guys a Mason jar of genuine NC corn likker..."It kills the germs that cause plaque".

Gasp100
02-23-2011, 07:08 AM
When I take my hand and hold it against the tuning machines, sometimes the volume or tone pot or sometimes palm against the bridge on some guitars they go from very noisey to nice and quiet.
What noise is this and can it be cured be a professionaly shielded guitar?

1) An expectation that shielding will reduce 60Hz hum..it will not..only RF

Pscheoverdrive
02-23-2011, 08:59 AM
@ Gasp100: Something's not grounded right... The bridge is supposed to be grounded and help fix that. Sounds like that needs to be sorted out... Shielding isn't going to do jack if the bridge isn't grounded right.

Husky
02-23-2011, 09:02 AM
John, my only question for you is, "Can I buy you a couple of beers some evening away from total madness?" I really enjoyed meeting you at NAMM, and would love to share war stories...

Absolutely and likewise ! Jim Kelley too ! :dude

Chris Rice
02-23-2011, 09:07 AM
When I take my hand and hold it against the tuning machines, sometimes the volume or tone pot or sometimes palm against the bridge on some guitars they go from very noisey to nice and quiet.
What noise is this and can it be cured be a professionaly shielded guitar?

1) An expectation that shielding will reduce 60Hz hum..it will not..only RF
Actually, that means that your bridge is grounded correctly. Having the guitar shielded (well) will essentially make it "nice and quiet" all the time, regardless of you touching the metal parts. As it is now, your body is acting as a shield when you touch the strings/bridge/knobs.

As a side note, one of my first professional gigs was as a bassist in a cajun blues band. I was using nylon tapewound strings, and had no ground connection. I ran a piece of #14 solid copper wire (house wire) from the bridge intonation screw to my wrist. Worked great, as long as I remembered to untie it between sets.

Husky
02-23-2011, 09:11 AM
:agree:rotflmaoThats funny, I had a Chapman stick player customer who used to stuff a wire down his pants since their hands are not always on the strings when playing. The pickups and electronics were not easy to shield without major work.

Actually, that means that your bridge is grounded correctly. Having the guitar shielded (well) will essentially make it "nice and quiet" all the time, regardless of you touching the metal parts. As it is now, your body is acting as a shield when you touch the strings/bridge/knobs.

As a side note, one of my first professional gigs was as a bassist in a cajun blues band. I was using nylon tapewound strings, and had no ground connection. I ran a piece of #14 solid copper wire (house wire) from the bridge intonation screw to my wrist. Worked great, as long as I remembered to untie it between sets.

Chris Rice
02-23-2011, 09:16 AM
You'd need a different kind of shield for that!

joshnorman
02-27-2011, 01:24 PM
So, what do you guys think about shielding hollow bodies or semi-hollows? I've got an es-333 that's a bit noisy, but there's no way I can line the entire lower half with foil or shielding paint. The wire of course is all shielded, do I just have to live with it? I considered constructing a small box or cage for the controls (I have an access panel since it's a 333 and not a 335) but I don't knw if it would be an improvement since the shielded wire is soldered to the pot casings anyway.

whitepapagold
04-01-2012, 01:41 AM
I just had to bump this thread as a great read!

Having just had my guitar shielded I noticed NO HF loss and HUGE noise reduction... Single coils, no shielding prior.

The difference is night and day and Im amazed.

WAY better clarity and definition...

I can see how it could be shocking to some as my guitar was quite noisey and now its not and absolutely sounds different... Quiet and better! It wasn't a subtle change.

But this thread and all the contributing builders really alleviated my concerns about tone loss from shielding!

Im a recording engineer for a living and a quiet guitar is a blessing.

Thanks! And you were definitely right!!!

Terry McInturff
04-01-2012, 02:14 AM
Thanks for re-introducing the topic, and I am delighted that you have benefitted from it. I dont engineer for a living but, I do record and just finished tonight's mix session one of those frustrating ones)...recording folks always appreciate a well shielded guitar!
BTW Id be half the guitar builder that I am if I did not know what engineering that I know.......

Ashe
04-01-2012, 10:14 AM
If you put additional metal in the vicinity of a guitar pickup's electro-magnetic circuit, it will change the frequency response and inductance. A Strat or Tele baseplate is a good example. Take a Strat pickup, put it on a table and measure it with and without a hunk of steel about 1/2" away. You will measure a significant and repeatable difference in AC electrical response. The pickup will inductively couple with any metal in the vicinity.

The question becomes at what distance, and mass and type of metal, does it become insignificant to the point that it can be ignored?

A good experiment would be to take a pickup, and put it in the middle of a grounded, copper lined box with symmetrical spacing from the pickup. Compare the AC electrical and frequency response of the pickup alone, with the response of the pickup in the grounded box. Do this with boxes of different sizes starting from say, pickup dimensions + 1/2" and increasing in 1/2" increments.

These data would put his question to bed for good. I've actually been meaning to do this, but I haven't gotten around to it.
lol.

thats when metal actually TOUCHES the pickup little jimmy.

whitepapagold
04-01-2012, 03:45 PM
Thanks for re-introducing the topic, and I am delighted that you have benefitted from it. I dont engineer for a living but, I do record and just finished tonight's mix session one of those frustrating ones)...recording folks always appreciate a well shielded guitar!
BTW Id be half the guitar builder that I am if I did not know what engineering that I know.......

I think if they train a monkey to push power on a mac and 3 on the keyboard I may be out of a job... heheh

It really was the thread I needed to read considering you, rice, suhr all chimed in and all said the same thing.

And I was one of those people who thought touching the guitar was grounding it... Nope.

And I thought my bridge wasn't properly grounded... Nope.

And I thought things would be noisey even with professionally done shielding... Nope.

So many internet myths and so much misinformation. Though its funny to see all the guys building guitars, PU manufacturers or legit luthiers agree on shielding and no tone loss- and the players/buyers who claim otherwise.

Though again, I do understand why people say the tone changes- it does. Its amazing how different a guitar sounds without all that noise. BUT HF loss, nope. And MUD? That theory is just ridiculous... Removing noise increases clarity and definition.

I can also see where if its not done properly, maybe people get different results.

But my tech uses the paint and knows how to do it and the results were phenomenal. I actually called him in shock after I got to the studio- and I NEVER call him after he does some work as its always great and exactly what I wanted.

But he warned me some people claim HF loss and he was glad to hear I hear none.

The funny thing is its a Blackguard replica (GVCG) and Im sure shielding is sacrilegious... Let alone all the other crap Ive done to it. But its my favorite guitar Ive ever played- and I hate relics.

And now, its quiet as a mouse.

I could rant for days as it was sooooooo noisey before and the second you stopped touching it... bbbbzzzzzzzzzzzzzzzzzzzzzz- as you played...

The high end I did lose was... bzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

paintguy
04-01-2012, 05:13 PM
Interesting stuff and makes me wonder about a fairly high end, small builder guitar that I own that has zero shielding in the pickup cavities or control cavity.:confused:

walterw
04-01-2012, 08:05 PM
If you put additional metal in the vicinity of a guitar pickup's electro-magnetic circuit, it will change the frequency response and inductance.

lol.

thats when metal actually TOUCHES the pickup little jimmy.
"lol"?

"little jimmy"?

what an odd tone to take. i think you'll find that ol' scott has done the research and knows what he's talking about.

fr8_trane
04-01-2012, 08:22 PM
I agree that good shielding ought to be S.O.P.

The carbon based sprayed paint is OK...however, it can go on too thin, and not be a great shield. Of course, more coats can be applied. There are sprayable metallic-based paints, and these seem to provide a better "one-pass" result.

I have this on order
http://www.mouser.com/ProductDetail/MG-Chemicals/841-340G/?qs=X5SXQx2ktnMdgW%252bQI%252bdK6A%3d%3d

http://www.mouser.com/images/mgchemicals/images/841-340g.jpg

Nickel based conductive spray paint. More conductive than carbon, more durable and it doesn't dry out like the stew mac stuff can.

walterw
04-01-2012, 08:58 PM
oh yeah; here's a shot of it in action, apparently it's pretty good stuff.

Well, as you can see in this picture that I posted in another thread, I paint a tab that reaches a pickguard screw. But the paint that I use is so much more conductive than StewMac's carbon/graphite paint (see the ohmmeter reading) that I can get away with that, and it makes things so much neater.
And its right at a pickguard screw so I get very good contact between this nickel-based coating of paint and the aluminum foil under the pickguard; it's like the pickguard is the lug that I'm screwing onto the conductive painted surface.
And by using aluminum foil, it doesn't oxidize over time like copper foil so the contact won't deteriorate over time.
I don't use conductive paint under the pickguard because the pickguard is flexible plastic, and conductive paint can get brittle and crack over time on a flexible surface.
http://pages.videotron.com/sirlarry/shield.jpg

walterw
04-01-2012, 09:14 PM
as for "eddy currents", it took me a while to grasp the concept, but i think i got it now:

if you shield too closely to the coil with a material that conducts electricity too well, like copper, aluminum, or (i think, because of its copper content) brass, the action of the pickup's magnetic field being disturbed by the strings actually induces a little current in the shield;

current moving through metal creates magnetism, and (lentz's law, i think?) that magnetism will always be in opposition to the original magnetism. (if it wasn't, we'd have perpetual motion machines!)

that opposing magnetism generated in the shielding is what affects the tone.

if i have it right, this is why brass covers (tele neck) affect the tone more than nickel-silver (gibson humbucker), because the brass conducts electricity better. (even though neither metal is magnetically attractive.)

shielding body cavities is a different question, because the shielding isn't close enough to the pickup magnets to get current induced into it. so in that case, the more conductivity, the better.

husky referred to a "big trick" for copper shielding close to pickup coils without incurring as much loss; i'm guessing some sort of gap to prevent eddy currents from flowing?

JBG
04-01-2012, 09:30 PM
Thx for posting this, Walter.

epluribus
04-01-2012, 10:22 PM
I have this on order
http://www.mouser.com/ProductDetail/MG-Chemicals/841-340G/?qs=X5SXQx2ktnMdgW%252bQI%252bdK6A%3d%3d

http://www.mouser.com/images/mgchemicals/images/841-340g.jpg

Nickel based conductive spray paint. More conductive than carbon, more durable and it doesn't dry out like the stew mac stuff can.

Another vote from me...I've had great luck with this stuff. And spray paint is so easy to use...

--Ray

Gradinger
04-02-2012, 10:15 PM
Great info in this thread. Surprised that there are so many mentions of static noise and not a peep about how useful a $.03 dryer sheet can be.

pima1234
04-02-2012, 10:42 PM
Mixed results with dryer sheets.

So many variables.

It can be so tough to nail down a particular problem. It takes time.

epluribus
04-03-2012, 03:15 PM
Drier sheets?

Chris Rice
04-03-2012, 03:58 PM
Anti static. Toss one in the case, pinch it under the pickguard, whatever. If static is your problem and not noise from a lack of shielding.

epluribus
04-03-2012, 06:57 PM
You guys are messin' with me right? :)

Chris Rice
04-03-2012, 07:09 PM
Nope!

epluribus
04-03-2012, 07:29 PM
Amazing. (Googling...)

Nork
04-16-2012, 11:04 AM
great read. tks - needed for information!

thesjkexperienc
04-16-2012, 11:50 AM
But, I'm allergic to dryer sheets. Found out the hard way.

burningyen
05-15-2012, 07:45 AM
For a new build, what are the reasons to go with shielding cavities vs. coax/shielded wire? Is it just because shielded cavities also shield the pickups and pots, or are there other differences in terms of the sound or ease of servicing?

dead of night
05-15-2012, 11:10 AM
I have an early Collings 290 with P 90 pickups. When I move my hand from the neck, there is extra noise. When I put my hand back, the extra noise disappears. Does this indicate there is something wrong?

Terry McInturff
05-15-2012, 11:17 AM
I have an early Collings 290 with P 90 pickups. When I move my hand from the neck, there is extra noise. When I put my hand back, the extra noise disappears. Does this indicate there is something wrong?

The extra noise is supposed to disappear. When you touch the strings you are connected to the ground circuit via the "bridge ground".

All is well.

football
10-22-2012, 02:02 PM
The extra noise is supposed to disappear. When you touch the strings you are connected to the ground circuit via the "bridge ground".

All is well.

Hi Terry, wondering if you use a shielded cable from the input jack?

cugel
10-22-2012, 02:27 PM
some of my best playing is from the radio stations i pickup when my fuzz face is on with guitar volume OFF

pima1234
10-22-2012, 09:35 PM
Had the same experience. LOL

In the end, I just couldn't deal with it.

some of my best playing is from the radio stations i pickup when my fuzz face is on with guitar volume OFF

1radicalron
10-24-2012, 07:39 PM
Yes, Proper shielding is a must. What should be mentioned again - is that no amount of shielding will stop an old Single Coil Pup Guitar from Humming. It can help isolate the hum, but will never completely eliminate it.

Jarick
01-11-2013, 12:10 PM
Can I bump this with a question...

Edit: Ah, I have lots of questions!

1. Will shielding a Strat cut down on noise from single coils if there is much, much less noise in the RWRP combined positions and with a bridge humbucker? The noise is really obnoxious even with a completely clean amp.

2. Oh and should I use copper or aluminum on the back of the pickguard?

3. Can I use the cavity shielding as a common ground or no?

4. Are we still grounding the back of pots with star grounding?

Thanks!

walterw
01-11-2013, 07:13 PM
the hum that goes away with RWRP pickups will not really be helped by shielding. what will be helped is the extra buzzing you get when you let go of the strings.

copper or aluminum will both work fine, but you can solder to copper.

no, using the cavity shield itself as the ground connection is not recommended, it's not as strong mechanically.

star-grounding guitars is just mis-applying amp wiring techniques; there are no ground loops (multiple ground potentials with current flowing between them) inside a guitar, which is what star-grounding (everything grounded to one point) is supposed to prevent.

ngativ
01-13-2013, 10:35 PM
Humm... i am starting to think that shielding the cavity might be a yet another myth.

pima1234
01-13-2013, 11:43 PM
Care to explain?

My one properly shielded guitar (a Carvin) has always had significantly less noise issues than my other guitars (particularly those with no shielding at all, not even paint). Installing Lace Alumitone humbuckers really helped, and opened the tone of that guitar.

I have a USA Strat with Kinman pickups and it has noise issues. Even Kinman strongly recommended full shielding.

My guitars with zero shielding are almost unplayable with any significant amount of gain (no... not high gain...), particularly with P90s of course.

ngativ
01-14-2013, 12:16 AM
Care to explain?

My one properly shielded guitar (a Carvin) has always had significantly less noise issues than my other guitars (particularly those with no shielding at all, not even paint). Installing Lace Alumitone humbuckers really helped, and opened the tone of that guitar.

I have a USA Strat with Kinman pickups and it has noise issues. Even Kinman strongly recommended full shielding.

My guitars with zero shielding are almost unplayable with any significant amount of gain (no... not high gain...), particularly with P90s of course.

Maybe i'll start another thread asking about that because nobody in this thread mentioned how a shielding really works. And something does't makes sense about shielding the pickup cavity.

GuitslingerTim
01-14-2013, 09:41 AM
Maybe i'll start another thread asking about that because nobody in this thread mentioned how a shielding really works. And something does't makes sense about shielding the pickup cavity.

Shielding the surface areas of the body cavity along with the underside of the pickguard and having them make contact will create a pretty effective Faraday cage if the cage is grounded to the circuit ground. Any stray radio waves that come into contact with the shielding will be conducted through the shield to ground instead of being transferred through the pots or wiring into the audible signal. It's that simple.

ScottB
01-14-2013, 10:22 AM
The physics that drive guitar phenomena don't exist in a vacuum.

If you want to understand what's really going in guitars, it seems that many times guitar forums are the worst place to look. There's so much misinformation, misunderstanding and incidences of opinions expressed as fact.

As has been stated above, typical shielding in guitars does next to nothing to stop what we call "hum", as by the generally accepted definition "60 cycle hum" is a magnetic disturbance. Pickups are great sensors of fluctuating magnetic fields and hum is generated in the pickup by the magnetic fluctuation induced by 60 cycle alternating current.

EMI can be reduced by shielding.

Here's a good overview of the topic.

http://www.analog.com/static/imported-files/tutorials/MT-095.pdf

I'm not an expert on this particular topic, and I readily admit I don't have all of the answers, but I have done enough research and made myself an expert in other areas such that I know where to look to find the right answers, or at least find the information that will start to guide me there.

edit: I don't mean to suggest that there aren't plenty of knowledgeable people here, clearly there are, there's just a very high noise to signal level and I imagine that for the novice it must be hard to separate fact from fiction.

AudioWonderland
01-14-2013, 10:28 AM
Humm... i am starting to think that shielding the cavity might be a yet another myth.

That would be a mistaken view. This is proven physics, not hokum.

ngativ
01-14-2013, 11:06 AM
Shielding the surface areas of the body cavity along with the underside of the pickguard and having them make contact will create a pretty effective Faraday cage if the cage is grounded to the circuit ground. Any stray radio waves that come into contact with the shielding will be conducted through the shield to ground instead of being transferred through the pots or wiring into the audible signal. It's that simple.

Yeah, i know that a faraday cage is cool. But the problem is that neither the coil nor the string are (not) inside of any faraday cage. In fact they are above, just outside. And i don't think that the wiring coming from the pickup of the control cavity is going to give up any interference picked up from the pickup.

i meant, that just puzzles me.

ngativ
01-14-2013, 11:09 AM
The physics that drive guitar phenomena don't exist in a vacuum.

If you want to understand what's really going in guitars, it seems that many times guitar forums are the worst place to look. There's so much misinformation, misunderstanding and incidences of opinions expressed as fact.

As has been stated above, typical shielding in guitars does next to nothing to stop what we call "hum", as by the generally accepted definition "60 cycle hum" is a magnetic disturbance. Pickups are great sensors of fluctuating magnetic fields and hum is generated in the pickup by the magnetic fluctuation induced by 60 cycle alternating current.

EMI can be reduced by shielding.

Here's a good overview of the topic.

http://www.analog.com/static/imported-files/tutorials/MT-095.pdf

I'm not an expert on this particular topic, and I readily admit I don't have all of the answers, but I have done enough research and made myself an expert in other areas such that I know where to look to find the right answers, or at least find the information that will start to guide me there.

Yeah this is not the best place too look, but i wish it was, so people that really understands how the gear works could share their knowledge and understanding to others. Thanks for the link!

pima1234
01-14-2013, 01:43 PM
Thank you. EMI tends to be one of the biggest problems (dimmers/computer screens/florescent bulbs/local AM stations).

The solution provided by your own pick up design would be excellent for those of us who just can't deal with hum and buzz. I assume they essentially eliminate the need for shielding?

The physics that drive guitar phenomena don't exist in a vacuum.

If you want to understand what's really going in guitars, it seems that many times guitar forums are the worst place to look. There's so much misinformation, misunderstanding and incidences of opinions expressed as fact.

As has been stated above, typical shielding in guitars does next to nothing to stop what we call "hum", as by the generally accepted definition "60 cycle hum" is a magnetic disturbance. Pickups are great sensors of fluctuating magnetic fields and hum is generated in the pickup by the magnetic fluctuation induced by 60 cycle alternating current.

EMI can be reduced by shielding.

Here's a good overview of the topic.

http://www.analog.com/static/imported-files/tutorials/MT-095.pdf

I'm not an expert on this particular topic, and I readily admit I don't have all of the answers, but I have done enough research and made myself an expert in other areas such that I know where to look to find the right answers, or at least find the information that will start to guide me there.

edit: I don't mean to suggest that there aren't plenty of knowledgeable people here, clearly there are, there's just a very high noise to signal level and I imagine that for the novice it must be hard to separate fact from fiction.

pima1234
01-14-2013, 01:44 PM
I agree that the whole thing can be very puzzling (not to mention, really frustrating sometimes!).

chervokas
01-14-2013, 03:10 PM
Yeah, i know that a faraday cage is cool. But the problem is that neither the coil nor the string are (not) inside of any faraday cage. In fact they are above, just outside. And i don't think that the wiring coming from the pickup of the control cavity is going to give up any interference picked up from the pickup.

i meant, that just puzzles me.

Well, just picturing it in my mind's eye, I think part of the coil, certainly in a Strat with the pickguard shielded, would be in the cage, unless you have the pickup heights adjusted up in the extreme.

ScottB
01-14-2013, 05:29 PM
Thank you. EMI tends to be one of the biggest problems (dimmers/computer screens/florescent bulbs/local AM stations).

The solution provided by your own pick up design would be excellent for those of us who just can't deal with hum and buzz. I assume they essentially eliminate the need for shielding?

Actually, they don't eliminate the need for shielding but they may eliminate the motivation for shielding. They eliminate the primary source of noise (magnetically induced hum), but any unshielded system will still be susceptible to buzz.

With great hum-cancelling you can get very quiet, to the point that you probably won't feel like you have to shield in most cases, but noise comes from different sources. Just like shielding won't get rid of hum, hum-cancelling won't get rid of buzz. If you want dead quiet, you need to shield (to get rid of buzz) and hum-cancel (to get rid of hum).

ngativ
01-14-2013, 05:45 PM
edit: I don't mean to suggest that there aren't plenty of knowledgeable people here, clearly there are, there's just a very high noise to signal level and I imagine that for the novice it must be hard to separate fact from fiction.

Oh well, you can filter the noise, correlating against facts and science is a good filter.. :) .

pima1234
01-14-2013, 11:03 PM
Filtering out noise doesn't work. I've tried with a good eq.

pima1234
01-14-2013, 11:05 PM
Thank you ScottB.

Very helpful posts here. Hum and buzz are definitely two different annoyances.

Time to gut some guitars... if I had the time (and a soldering iron).

kinmike
01-15-2013, 10:23 AM
I am surprised that the Illitch system hasn't been mentioned more in this thread. I think it was mentioned early on by John Suhr (?). The Illitch is meant to get rid of hum but you still need shielding, correct?

But then again, the Illitch system is around $275. Musicians are poor and engineers are cheapskates. :)

Mike

walterw
01-15-2013, 01:42 PM
The ilitch stuff is indeed a breakthrough, but again, that's all about the hum, a different issue from the buzz that shielding deals with.

GM Reszel
01-15-2013, 04:31 PM
200+ posts on whether shielding is good or not? OK, keep it simple - good shielding will eliminate the buzz that you get when you take your hands off the strings (and like radio frequencies). It will not eliminate noise that comes through the line (that which single coil pickups like to pass).

As for material I like copper the best and have found deck flashing at Menard's to be most excellent (see link below). Also excellent (and far less $$) is aluminum foil tape (although you can't solder to it like copper).

http://ecx.images-amazon.com/images/I/41-w9UhUibL._SL500_AA300_.jpg

beerijuana
01-16-2013, 02:56 PM
I bought a 6"x100" roll of .001 brass shim-stock from Lee Valley Tools (http://www.leevalley.com/us/wood/page.aspx?c=&p=40946&cat=1,43456,43407) many years ago, this allows me to shield most cavities "one-piece", including sides. It's quite easy to shape and it just loves solder.

http://www.leevalley.com/us/images/item/woodworking/assorted/27k0750s2.jpg

pima1234
01-16-2013, 10:25 PM
Nice. Works as well as copper?

I bought a 6"x100" roll of .001 brass shim-stock from Lee Valley Tools (http://www.leevalley.com/us/wood/page.aspx?c=&p=40946&cat=1,43456,43407) many years ago, this allows me to shield most cavities "one-piece", including sides. It's quite easy to shape and it just loves solder.

http://www.leevalley.com/us/images/item/woodworking/assorted/27k0750s2.jpg

beerijuana
01-16-2013, 10:49 PM
Nice. Works as well as copper?

RF Shielding-wise? Yup

Easier to work with as well, it's not as soft and "oilcan" prone as copper, and bends where you want it to bend, making for a neater job.

pima1234
01-16-2013, 10:58 PM
That's awesome. Thank you. Very helpful post.

RF Shielding-wise? Yup

Easier to work with as well, it's not as soft and "oilcan" prone as copper, and bends where you want it to bend, making for a neater job.

chervokas
01-17-2013, 06:22 AM
Well, brass is only 28% as conductive as copper. It's probably better to use a lower resistance conductor like copper or even aluminium (68% as conductive as copper).

walterw
01-17-2013, 11:21 AM
But the brass still has to be a better conductor than graphite shielding paint, which is plenty to do the job.

Chris Scott
01-17-2013, 03:16 PM
But the brass still has to be a better conductor than graphite shielding paint, which is plenty to do the job.


...especially as it's applied to sooo many lower-range instruments - here, lets rub a little carbon paint here and there, and we'll say it's SHIELDED!:)

ScottB
01-17-2013, 06:23 PM
It's not just conductivity, permeability enters into it too.

Here's a good technical article. This is actually the one I was looking for when I posted that thing above.

http://www.darcoid.com/images/uploads/pdfs/pg192theory_of_emi.pdf

ngativ
01-17-2013, 07:09 PM
It's not just conductivity, permeability enters into it too.

Here's a good technical article. This is actually the one I was looking for when I posted that thing above.

http://www.darcoid.com/images/uploads/pdfs/pg192theory_of_emi.pdf

Interesting... Does anybody here takes into account parameters like using a gasket, impedance, thickness , permeability, conductivity etc?.

And i am not still convinced about the effectiveness of shielding the pickup cavity.

walterw
01-17-2013, 07:11 PM
It's not just conductivity, permeability enters into it too.

"permeable" meaning "attractive to magnets", right?

your link and a couple that i followed suggested that thicker, really permeable shields are what would actually drain off the major 60-cycle single coil hum that normal shielding won't touch.

the problem (if i have this right) is that permeable stuff anywhere near a pickup promptly gets magnetized and changes the sound of the pickup (part of the classic tele tone recipe with the steel bridge and bottom plates) and that trying to surround a pickup with the stuff would render it unable to sense the strings anymore.

ngativ
01-17-2013, 07:32 PM
"permeable" meaning "attractive to magnets", right?

your link and a couple that i followed suggested that thicker, really permeable shields are what would actually drain off the major 60-cycle single coil hum that normal shielding won't touch.

the problem (if i have this right) is that permeable stuff anywhere near a pickup promptly gets magnetized and changes the sound of the pickup (part of the classic tele tone recipe with the steel bridge and bottom plates) and that trying to surround a pickup with the stuff would render it unable to sense the strings anymore.

Not really. That only happens if you put something between the strings and the pickup

walterw
01-17-2013, 08:19 PM
that's what i mean by "surrounding", which you'd have to do in order to block (or actually drain) the hum. i should have said "encasing".

ScottB
01-17-2013, 09:22 PM
"permeable" meaning "attractive to magnets", right?

your link and a couple that i followed suggested that thicker, really permeable shields are what would actually drain off the major 60-cycle single coil hum that normal shielding won't touch.

the problem (if i have this right) is that permeable stuff anywhere near a pickup promptly gets magnetized and changes the sound of the pickup (part of the classic tele tone recipe with the steel bridge and bottom plates) and that trying to surround a pickup with the stuff would render it unable to sense the strings anymore.

Permeability is a measure of a material's ability to conduct or support a magnetic field. Higher permeability pole pieces in pickups increase inductance because the magnetic field preferentially concentrates in the core material. This is also why higher permeability materials make better magnetic shields, they redirect the field away from whatever you're trying to shield. You can't block a magnetic field, but you can bend it.

Copper and aluminum have relative permeabilities close to one, so in magnetic terms they're no better than air.

But yeah, put enough material in a guitar to shield magnetically and you'll change the tone dramatically. Put anything permeable in that field and it will change the shape of the field and also couple with other materials in the vicinity. There's a thread a year or so back where I gave examples of the inductance change in a pickup when you have a chunk of steel within an inch or so of it.

ngativ
01-17-2013, 09:29 PM
But yeah, put enough material in a guitar to shield magnetically and you'll change the tone dramatically. Put anything permeable in that field and it will change the shape of the field and also couple with other materials in the vicinity. There's a thread a year or so back where I gave examples of the inductance change in a pickup when you have a chunk of steel within an inch or so of it.

Wouldn't that make the cavity awfully microphonic, hence the tone destruction?

ScottB
01-17-2013, 09:52 PM
Wouldn't that make the cavity awfully microphonic, hence the tone destruction?

It wouldn't have to.

The permeable shield would become (probably a significant) part of the electromagnetic magnetic circuit, generally acting to increase inductance and lower the resonant frequency.

ngativ
01-17-2013, 10:23 PM
It wouldn't have to.



Why not? if its permeability is significant enough, it would make sense to think that the pickup is going to pick the shield vibrations.

pima1234
01-17-2013, 11:42 PM
Isn't that the truth!

...especially as it's applied to sooo many lower-range instruments - here, lets rub a little carbon paint here and there, and we'll say it's SHIELDED!:)

pima1234
01-17-2013, 11:44 PM
That's really interesting, and may explain why many guitarist and luthiers choose not to have it installed.

Why not? if its permeability is significant enough, it would make sense to think that the pickup is going to pick the shield vibrations.

Buks
01-17-2013, 11:45 PM
There's a thread a year or so back where I gave examples of the inductance change in a pickup when you have a chunk of steel within an inch or so of it.

Does this mean that pickups right next to eachother influence eachother's sound?

torquil
01-18-2013, 12:49 AM
If you don't want hum, try an optical pickup.

chervokas
01-18-2013, 08:31 AM
That's really interesting, and may explain why many guitarist and luthiers choose not to have it installed.

Well, but as Scott noted copper has low permeability -- basically the same permeability as air -- so it's not really providing any magnetic shielding -- as we know, shielding with copper doesn't help combat noise that results from magnetic induction --only electrostatic shielding.

ngativ
01-18-2013, 11:31 AM
I am sorry but it seems that shielding the pickup cavity is a baseless myth

walterw
01-18-2013, 12:06 PM
I am sorry but it seems that shielding the pickup cavity is a baseless myth
no, it actually has happened, i've seen it with my own two eyes ;)

SamBooka
01-18-2013, 12:11 PM
I am sorry but it seems that shielding the pickup cavity is a baseless myth

MayBe somebody mentioned this already But if your outer wraps are grounded then your pick up already shielded to a decent extent

walterw
01-18-2013, 12:18 PM
that's usually not the case though; winding a fender pickup with the outer wraps to ground means the inner wraps are going to hot, which makes the polepieces noisy when touched.

fenders are all properly wound with the ground end of the coil against the magnet poles.

ngativ
01-18-2013, 12:39 PM
MayBe somebody mentioned this already But if your outer wraps are grounded then your pick up already shielded to a decent extent

Indeed, i think the "shielding" should be done from the pickups, not the pickup body cavity

walterw
01-18-2013, 12:48 PM
Indeed, i think the "shielding" should be done from the pickups, not the pickup body cavity
but that just exacerbates the problem, eddy currents affecting the pickup tone.

ngativ
01-18-2013, 01:13 PM
but that just exacerbates the problem, eddy currents affecting the pickup tone.

Well the goal is to increase the signal/noise ratio, hum canceling is the goal. If you going to use lamination for shielding there are ways to reduce the edgy currents. Seriously ,this not trivial to do without changing the original tone of a vintage single coil design. If you are going to shield the cavity walls there is a chance of making the cavity microphonic anyways, i am sure that's going to sound awful.

An theres no way to enclosure the whole pickup-string system, so the faraday cage notion seems very ineffective here. And taking into consideration an emi with a 60Hz frequency, i don't see how a thin foil is not transparent to it.

The only shield "solution" i've seen that makes more sense are the shielded cables, since those are enclosed by a thin foil plus a gasket, that is more consistent with the faraday cage notion, edgy currents, permeability, reflection and absorption and frequencies.

I might be wrong of course. Electromagnetism is not a trivial issue.

pima1234
01-18-2013, 10:59 PM
Right. It's the electrostatic noise that I have loads of problem with.

Well, but as Scott noted copper has low permeability -- basically the same permeability as air -- so it's not really providing any magnetic shielding -- as we know, shielding with copper doesn't help combat noise that results from magnetic induction --only electrostatic shielding.

ScottB
01-18-2013, 11:39 PM
Does this mean that pickups right next to eachother influence eachother's sound?

Yes

levous
01-20-2013, 02:24 PM
Stupid question but perhaps others will benefit.

When I play my single coil guitars through my rig (pedals to plexi clone), when I stand with my axe in precisely the right angle, I enjoy dead silence where otherwise there is much humming. This is, of course, exemplified with distortion/overdrive. Humbuckers are quiet. Some positions on the pickup selector switch are quieter than others. I am describing 60 cycle hum, correct?

Earlier in this thread (page 1, I believe), it was said that shielding will NOT reduce 60 cycle hum, only RF interference. So... Would shielding reduce this noise?

ScottB
01-20-2013, 02:32 PM
Stupid question but perhaps others will benefit.

When I play my single coil guitars through my rig (pedals to plexi clone), when I stand with my axe in precisely the right angle, I enjoy dead silence where otherwise there is much humming. This is, of course, exemplified with distortion/overdrive. Humbuckers are quiet. Some positions on the pickup selector switch are quieter than others. I am describing 60 cycle hum, correct?

Earlier in this thread (page 1, I believe), it was said that shielding will NOT reduce 60 cycle hum, only RF interference. So... Would shielding reduce this noise?

You're correct that the noise that is minimized at certain angles is hum. Shielding won't do much for this. You need hum-cancelling pickups.

Buzz will be much more constant with angle and shielding will reduce it.

pima1234
01-20-2013, 09:19 PM
Really wish we still lived to close to Delaware!

Great post. Thanks.

You're correct that the noise that is minimized at certain angles is hum. Shielding won't do much for this. You need hum-cancelling pickups.

Buzz will be much more constant with angle and shielding will reduce it.

angelodp
04-18-2013, 09:50 AM
I assume most know this, but I would include the Danelectro design as being perhaps one of the most effective hum buzz canceling designs. I have ano original 1457 Silvertone ( 1963) and its about the quietest electric guitar I have heard. Granted the pickups are low DC, but the copper box and pickups work to shield very effectively.

LonesomeBlues
04-20-2013, 04:06 PM
I'm glad this thread popped back up.
I'm going to try the copper tape shielding in the future.
For now, I'm putting new pups and pickguard in my strat.
First time doing anything like this....

The new pickguard has what looks like aluminum foil glued to back of it.
Is that to block the EMI, and do I need to ground it to something?
Or will it ground itself to the pots?
Jake

thared33
04-21-2013, 07:17 AM
I've got a weird buzzing in some of my guitars. My ESP and bass both with active pickups don't do this though. http://www5.zippyshare.com/v/3491230/file.html

I raised the gain so you could hear it better. Will shielding my guitars help with this noise, or is it that noise more of a ground loop type noise?

macmax77
04-25-2013, 10:44 AM
I simply know from experience, that there is no difference after shielding a guitar than there was before doing so.

When I say "shielding" -- obviously, everything needs to be properly grounded. Most humbucker pickup cables are shielded (Belden), or co-ax, and wires from the volume pot to the switch, as well as from the switch to the output jack need to be shielded cable OR wires that are twisted around each other, but beyond that, all the copper foil and carbon-graphite shielding paint in the body cavities is doing a whole lot of nothing. Especially when used with humbuckers. It might make you feel warm & fuzzy inside knowing that your guitar has it, but I assure you there is no difference in the noise that your guitar picks up...

This is an old thread but i for one will be buying a guitar from Terry or Mr Suhr in the future instead of one from you…. :D

Zingeroo
04-25-2013, 10:53 AM
I simply know from experience, that there is no difference after shielding a guitar than there was before doing so.

When I say "shielding" -- obviously, everything needs to be properly grounded. Most humbucker pickup cables are shielded (Belden), or co-ax, and wires from the volume pot to the switch, as well as from the switch to the output jack need to be shielded cable OR wires that are twisted around each other, but beyond that, all the copper foil and carbon-graphite shielding paint in the body cavities is doing a whole lot of nothing. Especially when used with humbuckers. It might make you feel warm & fuzzy inside knowing that your guitar has it, but I assure you there is no difference in the noise that your guitar picks up...

My strat (shielded) is quieter than my buddy's Les Paul (unshielded) in certain noisy environments.
It makes a HUGE difference, with all due respect.

pima1234
04-25-2013, 01:51 PM
Agreed. Shielding is so important. The pickups obviously play a role as well.

My Soloway NYA is one of the quietest guitars I've ever played. Great tone, single coils, no noise.

Rick Turner
06-02-2013, 01:09 AM
You guys simply have to separate the issues of electromagnetic noise from electrostatic noise if you're going to discuss this stuff at all.

Both can be dealt with, and the issue of tone changes with shielding are a matter of capacitance between hot leads and shielding...which can be minimized by not bringing shielding, in any form, close to "hot" signal leads.

I prefer to shield by means of a little copper foil + conductive paint the inside of pickup covers rather than wrapping copper foil close to pickup windings...if possible...for instance, to keep capacitive coupling to a minimum. So paint and ground the inside of Strat pickup covers...rather than wrap the coil directly=lower capacitive loss of highs. And that's what I do with the inside of my humbucker plastic covers...

And sometimes it isn't practical...so insulate the coil and wrap it with copper foil...and if you're smart, either leave a small gap or insulate the overlap. That will minimize the "shorted turn" effect.

There's both an art and a science to all of this...and every detail matters.

pima1234
06-02-2013, 01:21 AM
Great post. Thanks for keeping this discussion going.

gmaslin
06-02-2013, 05:55 AM
I'm loving this discussion. Rick Turner is absolutely spot with his advice to deal with mains (low cycle hum) and RF (fizz and hiss) separately. The most effective ways I've seen to deal with mains (cycle) hum are with ferrite (beads or toroid). Dealing with RF noise requires a process of elimination starting with the electronics cavity. I like a complete, all aluminum Faraday style enclosure but as Rick correctly points out, there is a danger of capacitively coupling the signal which may mute the higher frequencies, the same goes for the guitar input cable. Keep the wires as short and as far away from the cage as possible and note your results. The term 'buzz' describes the presence of both cycle and RF noise. Using the terms above to identify the type of noise you are experiencing will help you in dealing with it.

Ronsonic
06-02-2013, 06:54 AM
One of the things that always left me scratching my head in the shielding department ... Fender SC pickups and as far as I know all the 387,921 clones out there are wound and wired with the start of the coil connected to ground. If they were hooked up in the other phase, with the finish connected to ground the outer winds of the coil would act as a shield.

Leo didn't miss much - anybody know what he was thinking?

walterw
06-02-2013, 02:13 PM
simple; the shielding difference is negligible, but winding them the other way puts the magnets against the hot end of the coil, which makes the poles hideously noisy if you touch them (insulated or no).

pima1234
06-02-2013, 02:15 PM
Now that's an interesting idea!

pima1234
06-02-2013, 02:16 PM
I see. I have a guitar that becomes noisy when you touch the screws for the pickup selector switch.

simple; the shielding difference is negligible, but winding them the other way puts the magnets against the hot end of the coil, which makes the poles hideously noisy if you touch them (insulated or no).

Chris Scott
06-02-2013, 04:08 PM
I see. I have a guitar that becomes noisy when you touch the screws for the pickup selector switch.

Sounds like the switch isn't earthed.

walterw
06-02-2013, 04:16 PM
Sounds like the switch isn't earthed.
right; not the switch circuit, just the metal body of the switch itself. a bit of grounded shielding tape underneath, so the switch body contacts it, will do the trick.

any metal that isn't grounded in a guitar pretty much becomes an antenna, adding noise instead of shielding it.

Rick Turner
06-02-2013, 10:36 PM
Speaking of capacitance...if you use the start of a Strat or Tele coil as hot, the magnets...which are conductive...capacitively couple RF to the innner windings of the coil(s). The magnets act as little antennae for hum and buzz... Of course you can ground the magnets...and capacitively couple the inner windings to ground killing some output. Damned if you do, damned if you don't... Never a dull moment in pickup design.

pima1234
06-02-2013, 11:01 PM
Awesome! Thank you.

My tech didn't want to deal with it and I don't own a soldering iron (yeah, I know...). But I know someone who does.

Sounds like the switch isn't earthed.

right; not the switch circuit, just the metal body of the switch itself. a bit of grounded shielding tape underneath, so the switch body contacts it, will do the trick.

any metal that isn't grounded in a guitar pretty much becomes an antenna, adding noise instead of shielding it.