Copper foil shielding, and other noise issues

[Huckleberry]

I have a G&L ASAT Special (US made). lately, I've been using more distortion, and I've been digging the way my ASAT & American Series Tele sound as "hard rock" instruments. Naturally, as they have single coil pickups, they also have 60 cycle hum. Now, I know I'm never gonna eliminate the hum if I keep the original pickups. And that's okay. As walking around my room can increase/decrase the hum, I know it is not entirely the guitar's fault, and that I no doubt live in some mystical magnetic interference crossroads of the universe. That's okay, as well. Long as I have a place for my stuff. My issue is this:

The Tele is much, much quieter than the ASAT. I attribute this to the ASAT's higher output (yet I've been reading a lot lately about how quiet the MFD pickups can be...? Maybe this is a relative statement, as in "for the output they have, and the fact that they're single coils, these MFDs are darned quiet!" Maybe I'm just reading a bunch of stuff from clean & twangy country pickers). Using a Boss DS-1 pedal with the gain 3/4 of the way up results in the mildest of buzzing for the Tele. Very acceptable to me.

I've been considering having the ASAT shielded by my tech. It'll be fairly inexpensive, and reversible should I choose to undo it, so I was wondering if anyone has done this and considers it a worthwhile endeavor. I'm really only looking for a little noise reduction anyway. I'm not trying to make the guitar something it isn't, just trying to tame the hum a wee bit.

My tech had also looked over my ASAT a while back and declared it properly grounded, etc.

In addition, both the Tele & ASAT have a high pitched type of buzz when I have the volume knobs up all the way, and I'm not touching the bridge or the strings. I more often than not get a quick static crackle when touching the knobs of either guitar whilst not touching the strings. Is this a normal occurrance with "Tele" type guitars? Is it connected to the fact that these guitars have metal knobs & control plates? I'd cry "foul" or "defect", but it seems unlikely that I would purchase two different instruments from two different manufactures that would both go snap, crackle & pop in this manner.
thank in advance for your replies & input.

-Huck

[Offshore Angler]

Huck, the pop you hear is most likely from static on the pickguard. The guard is a non-conductor so it will build up a static charge. It can be negated pretty effectively by adding a layer of foil to the bottom of the guard and then creating a path to ground from the foil.

OK, 60 Hz buzz. Whenever you go into a high gain situation it will be a problem. Lot's of people focus on the guitar, but there are other sources as well. Cables, stompboxes, power supplies, and anything with wires in it can be a source. The best way to fight the buzz in high gain is with a noise gate. It can be set to tame the buzz when you're not playing, and when you are, the buzz is usually not noticable.

The other thing to attack is the source of the buzz. Sometimes just leaving off a florescent light or the TV will cure the problem.

You can sometimes see if it's a RF induced buzz vs a power problem bu simply turning the guitar 90 degrees and listening for it changing. If it's RF, look for the source.

[pc]

I've had two guitars shielded and did not like the negative effect it had on the tone--there was a noticeable reduction in the high-end sparkle of my sound. Can't imagine it made a difference to anyone listening in the crowd, but it bugged me, esp. doing studio tracks.

Others have done it and aren't bothered by the tone change, and surely someone will chime in soon and say there's no possible way the tone could change and that I was hearing things. Either way, wasn't for me.

BTW, an even lower-tech way to eliminate the static pop on your pickguard is to wipe a Bounce dryer sheet across it once before playing. Problem solved for the whole gig or session.

[frank thomson]

there's no possible way the tone could change and that YOU was hearing things.

ta-daaaa

[DrQuist]

By shieldign the guitar you change the capacitance of the guitar .. it does change the tone .

My firs t HUGE experience was in 1978 when I was touring with Dave Mason (former member of 'Traffic' ) and I was asked to try to remove the 60cylce problems we were facing on tour ...especially with older Theaters ( the Fox Theater in Atlanta was the gig he asked me to do something about this headache) .

In older venues .. these buildings were modded to accommodate 'modern' times .. so AC lines were bundles and run together.. when you faced these at 90degrees .. you would get an increase in noise and at angles we got Radio signals !!!

So .. I took apart an old Strat we had that was the #3 guitar and foil lined the pickup covers , soldering a ground wire to that copper , and wrapping the pickup coil with copper and grounding that . That did make a difference ! But not enough .
So I shielded the control cavity and pickup cavities ...again less noise ..but still the Gibson guitars were quieter .

So ...I removed the cloth cable from the pickups and installed dual conductor shielded cable on each pickup ... now everything was shielded .
That was really quiet ....but it no longer sounded lik ethe unshielded Strat we had .

The high end was gone .. it did not have the sparkle any more .

So yes shielding WILL help with noise problems , but there are trade offs .

Hum canceling pickups also have trade offs .

So you must ask yourself .. what can I stand /tolorate , and what and where will I be using this ?

If you are recording ... by the time you add all those other tracks .. you won't hear it .. get OVER IT . Hendrix sure dealt with it ...so did SRV .

The dryer paper thing it an easy quick fix and is very simple to do .

Twist the leads so they are spiralled .. that will also help .

Then .. add a .001mfd to the two hot lugs of the volume controls of your amps... many already have that .. but this will give you sparkle if the amp lacks that after the shielding .

An easy to do mod . And easy to test ..... solder one end...play ....listen .

Turn off the amp .. solder the second leg to the other pot lug ... turn amp on .... play and listen .

DON'T solder with the amp on ... please .

[photoweborama]

I do shield my guitars, but I have a theory on that.

I use cheap aluminum tape, or shielding paint I think that you only need a contiguous shield for it to work right and low resistance is not a factor for guitars. From what I've seen from my own guitars, the more conductive the shield, the more of the highs are cut.

My shielding does not provide zero resistance. Some might say it has poor continuity, but I think that because of that, less of the highs are cut, but the shielding still does it's job.

[DrQuist]

I have come to a compromise with this whole issue .

I install shielded cable from the jack to the controls,
I line the control cavity with Aluminum ducting tape ,
I put the same tape on the guard where the controls are ... and the cavity tape gets rolled over the edge of the route and when the guard is screwed down .. the tape of both the cavity and the guard touch ... this completes the circuit .

I then stop there.
THis cuts out most of the hum & without cutting all those highs .
I have done it this way for twenty years .

[DrQuist]

FYI .. it is impossible to hear the difference between the copper foil and the aluminum tape shield ...Even Eric Johnson can't hear that .

[photoweborama]

Well, I can always take it out.. I try to do all my mods in a way that it can be removed. That's why I don't use shielding paint any more. you can't take it out...

I'm not 100% sure if I even need it anymore. It seems to me that I stated shielding because of RFI on my first MiM Strat with cheap cables and cheap plastic case DanO pedals. It's a possibility that I don't even have those problems anymore since I no longer have any low end gear...

And as far a Eric Johnson not hearing it.... Well... sometimes I wonder about that guy... For example, the George L's directional thing.. I've emails back from them and they say the way they are manufactured, it makes absolutely no difference what direction the cables go...

But thats another discussion altogether...

[frank thomson]

pc, hope you know i was bustin yo chops

and fezz said, like 10 words i never knew existed!

[Mahaqa]

Is there a simple way of measuring the relevant capacitances we're discussing here?

And yes, there is no difference between copper and aluminum foil for this purpose. Both metals have almost identical electrical properties.

[boobtube21]

I thought copper had greater conductivity.

[photoweborama]

I thought copper had greater conductivity.

It does!

[DrQuist]

But you are NOT running electricity of any level through the foil .. you are just creating a barrier .

So any metal that can be ground will do that . Aluminum is more cost effective and can be had at nearly any Hardware store ... where as copper foil tape costs far more ... and must be had from specialty outlets .
The plus to it is you CAN solder the joints together .. the aluminum needs a check for the pressure fit with a meter to insure all pieces of the shield are 'connected' .

[photoweborama]

You can also get the copper foil at any stained glass shop!

[pc]

pc, hope you know i was bustin yo chops
...

Yeah, I knew, and I thoroughly enjoyed it.

[Mahaqa]

I thought copper had greater conductivity.

The difference is extremely slight and could never possibly make the slightest difference in this application, even if the foil was being used as "chassis ground" to eliminate other ground runs in addition to its shielding function. If conductivity mattered for simple cavity shielding, then that paint would be out of the question because its conductivity is pretty low. I was just metering some last night.

Copper's advantage is merely that it can be soldered.

[boobtube21]

If conductivity mattered for simple cavity shielding, then that paint would be out of the question because its conductivity is pretty low.

I just said that thing about copper in response to someone saying copper and aluminum had identical electrical properties. I would imagine anything metal could do a decent job of blocking RF interference.

[photoweborama]

I would imagine anything metal could do a decent job of blocking RF interference.

Like Megadeath or Metallica?

[boobtube21]

Exactly!

[Mahaqa]

Exactly!

Well, I'm glad we got that straightened out!

Hey, you geniuses make yourselves useful and help me out with this, then:

OK, I'm trying to straighten out what looks to me to be a pretty serious wiring mess in my new HH w/OEM Duncans. The basic layout is exactly the same as the one here.

OK, so far, so good...but here's where the trouble starts: Every (and I do mean EVERY) straight run is done not with plain wire, but with co-ax with the shield grounded at each end.

Here's what I mean -- open the wiring diagram in a different window and sing along...

See the little straight run between the volume & tone pot for each pickup? That would normally be just a little wire about 1.5" long. On these, there's six or seven inches of co-ax in a messy loop with the braid soldered to the backs of the pots at each end and the center conductor connected between the two lugs.

OK, see the 3-Way toggle for the pickup selector? That's a long run on this guitar. Instead of three wires and a ground, this is done with three co-ax wires with ALL the braids grounded at both ends.

Am I correct in assuming that these are -- instead of preventing EMI through aggressive shielding -- creating a lot of noisy ground loops?

I recall reading somewhere that if you used the shield of co-ax simply as a shield, you should not ground it at BOTH ends. If that's so, it would explain the problem here.

What is the PROPER way for these to be wired for minimum noise & ground loops?

Thanks for any help!

[photoweborama]

I know with old style COAX Eithernet cable, that you could only ground one terminator on one side. If you did both, it made it a huge antenna and killed your bandwidth..

[DrQuist]

Because SD does not draw out in that drawing the type of wire you are using ... I will explain this verbally .... this is going to be some typing !

The pickups need both volume and tone .
Because you need volume to HAVE tone ... the pickups are routed there FIRST.

Pots can be left handed or right handed .. but standard issue 'Audio' taper is made for right handed (there are more righties in the world than us lefties --FYI I play right handed ) .

So with the shaft of the pots aimed at the floor and the soldering lugs toward your face .... the lug on the right needs to be soldered to the back of the can .
This can be bent over and soldered or a wire inserted thru the lug and connected that way.
Do this to BOTH volume pots.

The resistor on the inside of the pot has two ends .... one you just grounded ... the other end is the lug on the left .
WE will call that lug the "in" lug .
The center lug is the "out" lug .

To give the pickup it's volume ...solder the hot lead to the left lug of it's pot .
That same pickup needs tone ... so run a wire from the hot lug of the volume control to the center of the tone pot (I know ..it looks different than SD's drawing ....this is how Gibson did things ...get over it . )
The wire from volume to tone has a shield on it .. solder that to the can of each pot . This gives BOTH controls a connected ground .

Now you need to be able to select the pickups ... so take a shielded section of wire , and solder the "Hot" to the center lug of the vulume pot. Do this for both controls .

The switch has four hot connections and one ground lug . See that ?
Each side has a short and a long connection going to the 'bat' .
When that bat is centered ... both pickups will touch the connections .
When the bat is moved up ..the bridge pickup connections are opened up .. see that ?
When the bat is flipped down .. the neck connectins are now open . Do you see that ?

Understanding HOW the switch works really helps in wiring this .

There is a lug that is in the center of those hot soldering places .
This is connected to the framework of the switch . That is the ground lug .

So ... decide which side is bridge ... do this by flicking the bat to see what connections open when the bat is down .
Run a shielded cable from the center lug of the volume pot to the short lug of those two .
Solder the ground wire from that shield to the ground lug of the switch . I suggest you 'tint' the wires first . Bend that shield wire and run it through that lug and crimp it with some needle nosed pliers , don't solder it yet .

Now the other pickup .. do the same thing for that on the opposite side of the switch .
Again .. solder the shield of that piece of cable to thecan of that pickups volume pot and the other end to the switch ground lug .

NOW solder both of those wires to that lground lug on the switch .

THe last part of the shielded wiring ... is connecting the two long lugs at the switch with a piece of unshielded wire (anything shorter than two inches really does not require shielded cable ) . As this piece is less than 1/2" long ... just use a short section of wire for this .

Then ...you need to find the hot shielded cable from the input jack .... solder the hot wire from that to either lug that you just soldered that short piece of wire to ..and solder the shieled ground to the ground lug of the switch .

We must back up for a moment .... the cap at the tone pot needs to be moved .
The right lug of the tone pot needs to have one end of that cap soldered to it .. and the other end of that cap soldered to the rear of the can of the pot .

The last soldered wire is the bridge grounding wire ..Solder it to any pots can .

Does this make sense to you ? Hope so .

[photoweborama]

Like Megadeath or Metallica?

[Mahaqa]

So with the shaft of the pots aimed at the floor and the soldering lugs toward your face .... the lug on the right needs to be soldered to the back of the can .
This can be bent over and soldered or a wire inserted thru the lug and connected that way.

So you are not of the opinion [vid. GuitarNuts] that this is a bad practice, and that these should be star-grounded?

The wire from volume to tone has a shield on it .. solder that to the can of each pot . This gives BOTH controls a connected ground.

Now you need to be able to select the pickups ... so take a shielded section of wire , and solder the "Hot" to the center lug of the vulume pot. Do this for both controls .

The switch has four hot connections and one ground lug . See that ?
Do you see that ?

Actually, it doesn't. It's like the the one in the diagram: Three connections, plus ground.

Understanding HOW the switch works really helps in wiring this .

I understand how it works, and it's wired correctly in terms of function (in fact, the whole mess is -- I think), I'm concerned with noise and ground loops.

Run a shielded cable from the center lug of the volume pot to the short lug of those two .
Solder the ground wire from that shield to the ground lug of the switch...solder the shield of that piece of cable to thecan of that pickups volume pot and the other end to the switch ground lug .

NOW solder both of those wires to that lground lug on the switch .
[...]
Then ...you need to find the hot shielded cable from the input jack .... solder the hot wire from that to either lug that you just soldered that short piece of wire to ..and solder the shieled ground to the ground lug of the switch .

Does this make sense to you ? Hope so .

I'm having a hard time extracting the answer to my specific question, but if I understand you correctly, then the existing wiring is correct in having all these shields grounded at both ends? This arrangement is not producing ground loops?

I was under the same impression as Photoweborama, above: That shields not in the circuit should not be grounded at both ends.

Again, I'm not asking how to wire this instrument to make it work, as it already does. I'm asking how to wire it to eliminate ground loops and noise sources in the factory wiring. Thanks for any clarification on this.

[photoweborama]

I really don't think connecting your shields at both ends will cause a problem. Guitars are such low power circuits. Guitarnuts in general, their shielding info is way over kill for a guitar.

All that star grounding, etc. work great for much bigger applications, but guitars only put about 1/10000 of a load that guitarnuts info is really designed to help.

Sure, it works, but it's like using a VW engine on your lawn mower....

[Wilko]

Actually, it's almost impossible to "star ground" a strat, specially if it's wired right.

For one thing, the foil (or sheet of metal as on my 1960) will connect the chassis of all harware to that sheet of metal. The only "ground" wire need is the one that goes from the chassis to the tremolo spring claw and to the chassis of the jack. The latter is where a piece of Gibson style braided wire can help to reduce RF noise.

[Offshore Angler]

Hmmm, the old mad scientist in me is thinking. A metal screen will work just a well as a sheet, provided the openings are smaller than 1/2 the wavelength. And I'm thinking that might stop the capacitance problem to some degree... maybe we CAN shield and not effect tone.

[Offshore Angler]

Exactly!

I'm in little over my head, since electrical engineering ain't my bag. Just remembering some snippet of useless knowledge from Physics 201. Now, if it had an afterburner I could actually speak with some authority.

[Don]

Just like they used to staple above the chassis in SF , BF,and Brownfaced Fenders...

That stuff will tear your finger right open!

So will the edge of an old Peavey Bandit chassis (learned that the hard way last week)!

[boobtube21]

...but it's like using a VW engine on your lawn mower....

What's wrong with that?

Shit, if I had a lawn...

[DrQuist]

The SD drawing has a wire that runs between each tone pot ... you DON'T want that !!!! That creates the round loop .

[DrQuist]

The Gibson wiring is exactly what I typed out for you .

You need to have a ground wire connect from the tone pot to the volume control ... the only place they connect (as far as ground is concerned ) is at the switch . The hot wires are the 'hard' part .

[sapi]

I have come to a compromise with this whole issue .

I install shielded cable from the jack to the controls,
I line the control cavity with Aluminum ducting tape ,
I put the same tape on the guard where the controls are ... and the cavity tape gets rolled over the edge of the route and when the guard is screwed down .. the tape of both the cavity and the guard touch ... this completes the circuit .

I then stop there.
THis cuts out most of the hum & without cutting all those highs .
I have done it this way for twenty years .

I have done all this except the shielded (output) cable from the jack to controls. My guitar with the Fender '69 Custom Shop pu's hums a lot! Trem is grounded. Seems also interference is coming from the mains supply and gets boosted by pedals. I thought about using a cable like Gibsons' output shielded cable to jack. Will it affect the tone of the strat? I'm using Callaham's wiring schematic with tone blender and Fender "Greasebucket" tone control. Thanks!

[refin]

I have a tele pickguard shielded with a thin copper sheet that came in the shape of the guard--also shielded the cavity of my '62 strat with copper foil,and both sound really good.It took out alot of the hum.