Shielding question

[rspst14]

Hey guys, maybe someone can answer this question for me. I was told by a luthier that shielding with copper tape is totally useless unless wired properly. I understand the purpose and concept of star grounding, but one thing he said threw me for a loop. He said all grounds should go to one central location, with the exception of the ground wire that gets soldered to the shielding tape. He said that one end of this wire should be soldered to the copper tape, and one end should be soldered to the ground on the output jack. He claims that grounding the shield anywhere else would completely remove it from the circuit, making it completely useless. This isn't a hack tech, he seems to really know what he's talking about. But I'm not so sure about this. I'd never heard this before, and his reasoning doesn't make sense to me. I'm not saying he's wrong, but I've never heard anyone else say this. Can anyone comment on this one way or another? I just shielded my Strat project with copper tape, and I'm going to start wiring everything up as soon as the last few parts arrive next week. I'm wondering if I should follow his advice when grounding the shield. Any help would be appreciated. Thanks.

Ryan

 

[jeremy]

Re: Shielding question

im not sure why it would make a difference.
ive run the shielding wire to the central ground with no ill effects

 

[theodie]

Re: Shielding question

When I sheild a guitar I take a continuity meter and touch everything with it to make sure everything is connected to ground. If everything is going to ground, I cant see how it would make alot of difference. If you hear the continuity meter beep, it is part of the circuit.

 

[TheArchitect]

Re: Shielding question

Since everything ultimately goes to the ground tab on the output jack he is wrong. The whole point of Star grounding is to eliminate grounding loops. Its important to make sure there is conductivity between all pieces of tape used. Past that I didn't run wire from the shielding to anything because a path to ground already exists through the pot shell (the shell must be in contact with the shielding obviously) used as the grounding point for all of the grounds. Regardless of which way you do it, Copper shielding does make a difference as long as it has a path to ground.

 

[rspst14]

Re: Shielding question

Here's what he said regarding this...

"the whole point of shielding is the "modified star grounding" method. you can shield a guitar everywhere, but if your grounds are not "circuited" correctly.. then you didn't do anything.

It's such a simple idea.. You solder all your electronic grounds to one point EXCEPT YOUR OUTPUT JACK GROUND.

that one you solder to the shield. thereby forceing your shield to become part of your guitars circuit. otherwise your shield isn't even in the circuit no matter how many grounds you solder to it. and don't bother telling me that if you check your grounds with a meter that the shield IS in the circuit.. It only in the METER"S CIRCUIT when you check it that way. not in the guitars circuit."

Does this make sense to anybody? I'm still not convinced he's right about this.

Ryan

 

[Fritz6]

Re: Shielding question

If you hard wire the pot to the shielding and you get the continuity beep and 0 ohm resistance, your good to go. What the hell does "in the meter's circuit" mean?

The beep means that the connection has electrically continuity. What would the point of multi-meters be if it didn't?

The shield is part of the circuit whether the central grounding pot is screwed down to it, or it's hard wired to the pot, or the jack is hard wired to it. I recently did a friends strat like this:

Pups hard wired to vol pot and vol pot grounded to itself
Vol pot screwed down to aluminum shielding plate
Tone pot-Blender pot and 5-way screwed down to shielding plate (no hard wire connection to ground)
Ran wire from vol pot to metal strip that was screwed down to shielding paint
Bridge and jack ground hard wired to metal strip

Dead quiet and I only had to solder the 3 pups to the back of the pot. To me it seems like there's a bunch of different ways to ground that add up to the same thing electrically.

Just go with the one that's easiest and or quietest.

 

[rspst14]

Re: Shielding question

I emailed him and asked him for clarification, here's what he said...

"The reason is as simple as the fact that electricity , like water seeks the path of least resistance right,
If you have a sheild around all your electronics, and the ground wires are all connected to one point, you have eleminated the sheild from the circuit.
BUT by haveing all the grounds EXCEPT the output jack ground wire soldered to one point ( say back of a pot) and THEN solder the output jack ground wire to the SHIELD, THEN you have forced the shield to become an active part of the circuit. and thereby will do it's job much better."

I bet Artie would know for sure, I'll PM him and see if he can impart his wisdom upon us.

Ryan

 

[BlueSnMettle]

Re: Shielding question

I was just thinking to myself, as I was half way thru reading the responses, I bet Artie knows. Let the rest of us know what the Artmeister sayeth, Ryan.

Peace,

Darrin

 

[Fritz6]

Re: Shielding question

Kent S. too. He's like Yoda with this stuff.

 

[Artie]

Re: Shielding question

Ok, let me just say, that I'll impart my opinion here, not necessarily wisdom. The flow of electrons can sometimes be voodoo as much as science. Also, I want to be careful about challenging someone else's knowledge when they aren't here to defend themselves.

I do take issue with a couple of things said:

"the whole point of shielding is the "modified star grounding" method. you can shield a guitar everywhere, but if your grounds are not "circuited" correctly.. then you didn't do anything.

It's such a simple idea.. You solder all your electronic grounds to one point EXCEPT YOUR OUTPUT JACK GROUND.

that one you solder to the shield. thereby forceing your shield to become part of your guitars circuit. otherwise your shield isn't even in the circuit no matter how many grounds you solder to it. and don't bother telling me that if you check your grounds with a meter that the shield IS in the circuit.. It only in the METER"S CIRCUIT when you check it that way. not in the guitars circuit."

I'm not sure what he's getting at here. This doesn't make any sense to me. I have a feeling that its based on this erroneous concept:

The reason is as simple as the fact that electricity , like water seeks the path of least resistance right . . .

I wish they'ld never taught this in high school science classes. Its just not true. Its like saying "automobiles are green." Well, yeah, some are. But the statement implies that they all are.

Electricity does take the path of least resistance. It also takes the path of highest resistance. The more correct axiom is:

Electricity takes every path it can.

It doesn't matter where, or to what, I ground a shield to. The important thing is, that when stray AC or RF energy comes into the guitar, its shunted to ground before it gets to the coils. This will occur no matter where the physical connection of the ground "wire" is connected.

On a side note, and I hate to keep beating this horse, but (IMHO) "ground loop" is not the correct term to describe noise problems inside a guitar. The maximum distance between ground points, and the voltages associated with the internal workings of a guitar, are simply not great enough for there to be a significant voltage drop from one point to another.

(A voltage drop, from one ground point to another, is what causes "ground loops".)

If I can think of more to add to this to help clarify my position, I'll add it later.

Hope this helps.

Artie

 

[BlueSnMettle]

Re: Shielding question

So it was basically BS, huh Artie?

 

[TheArchitect]

Re: Shielding question

Well I'll call Bullsh1t on this one. The guy really doesn't understand as much as he thinks he does. Artie is on the money, if the shielding has a path to ground thats all that matters. If you have continuity from the shielding to the sleeve of your guitar cable you are in business. You need to find a new tech that won't spew BS about things he doesn't understand.

 

[Artie]

Re: Shielding question

So it was basically BS, huh Artie?

Well . . . I wouldn't call it BS. The guy is probably just going with something he's observed through experience. But he may be misinterpreting one small aspect of something.

And . . . he may be correct, but for a different reason. I haven't really shielded any of my guitars, because I haven't needed to. Consequently, I'm talking only through theory.

I could be wrong.

Artie

 

[BlueSnMettle]

Re: Shielding question

Well . . . I wouldn't call it BS. The guy is probably just going with something he's observed through experience. But he may be misinterpreting one small aspect of something.

And . . . he may be correct, but for a different reason. I haven't really shielded any of my guitars, because I haven't needed to. Consequently, I'm talking only through theory.

I could be wrong.

Artie

So PC Artie, you're making me sick. :laugh2: I dunno, but to me a ground is a ground, right, as long as it's grounded to something else that's grounded and as long as I stay on the ground & don't do any acrobatic moves then I shouldn't expect any extracuricular ungroundedness. Right?

Ground & Peace,

Darrin