Copper shielding ??

Re: Copper shielding ??

Postby RiverRat » Mon Oct 04, 2010 6:45 pm

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Last edited by RiverRat on Tue Feb 22, 2011 2:18 pm, edited 1 time in total.
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Re: Copper shielding ??

Postby Rick Turner » Mon Oct 04, 2010 7:37 pm

RiverRat, thank you for so eloquently expressing yourself and showing all here your true colors. I just hope your post isn't edited or removed by yourself or any others. It's fantastic to see the angry soul behind the mask. You've outed yourself in an absolutely spectacular fashion.

Perfect, my man...go for it...

Hope you had a virtual bib on for all the spittle...
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Re: Copper shielding ??

Postby waldo041 » Mon Oct 04, 2010 7:38 pm

Chassis Ground = Shield
Signal Ground = Star/Buss Grounding

even though they DO connect/conduct together, they are 2 different things and should be classified as such. also, even though both can function without the other, there are reasons why they should be connected together.

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Re: Copper shielding ??

Postby Mandoborg » Tue Oct 05, 2010 4:19 am

One of the things that i've always liked about lutherie is the comradre of it's participants. Everybody has there way of doing things and there seems to be more than one way to do most things in lutherie. This discussion started out really interesting , then something ugly happened and it turned nasty. Rick has been a great help to me over at Mandolin Cafe in my building and as you all know has been dealing with instruments forever. Riverrat has also posted some really informative information as well, but somehow this has gone horribly wrong. You can agree to disagree without being disrespectful. What scares me about this stuff is i've seen really good people shy away from forums for just such a thing........ there is room here for everyones ideas. We are adults.

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Re: Copper shielding ??

Postby Rick Turner » Tue Oct 05, 2010 6:04 am

Jim, at the Mandolin Cafe many if not most of the luthier/participants use their real names. Nobody hides behind a handle to spew poison, and there is a great deal of mutual respect. Disagreements do not get personal, and it is the best luthiers' forum on-line with some of the absolutely top builders, engineers, researchers, and historians all discussing topics in an adult fashion.

I have found that too many of the more electric forums seem to attract people whose social skills are about like that of a spoiled and pissed-off five year old. It's like this over at the Pickup Makers' forum as well. Under these circumstances, I'm much better off staying silent and keeping my knowledge well to myself and just using what I know in the service of my clients.
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Re: Copper shielding ??

Postby Tennessee Jedi » Tue Oct 05, 2010 6:55 am

Rick Turner wrote:
Inside the guitars we started with making sheet copper boxes soldered together.

Image
Looks like thats what my builder is doing ....
Old school !
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Re: Copper shielding ??

Postby strumminsix » Tue Oct 05, 2010 7:06 am

I think y'all need to chill a bit.

Rick, having you here is a great honor and your historical perspectives and experience goes without saying is so well received and appreciated.

Riverrat - too bad ya didn't take the high ground. You'da had him dead to rights with calling him out "end of discussion" in the middle of a debate :lol:

Personally, I'd love to see this debate continue, albeit more civilized, with the clarified info from Waldo:
Chassis Ground = Shield
Signal Ground = Star/Buss Grounding

even though they DO connect/conduct together, they are 2 different things and should be classified as such. also, even though both can function without the other, there are reasons why they should be connected together.
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Re: Copper shielding ??

Postby JonnyBoy » Tue Oct 05, 2010 7:29 am

So if I am getting this right, You want to have a shield in the guitar cavity. this shield is grounded to the buss. Then, all the components are ISOLATED from the shield with a rubber stopper or the like, keeping them from touching the shield and creating a loop from buss to component and component to buss. Each component is then connected to ground through its own separate wire, isolated from each other except for the buss point, but the path of least resistance will keep the signals going in one direction. The buss point is then connected to the jack ground. I think that's what I am hearing. But if the path of least resistance is going to the final ground point, why would a loop/mesh matter anyway since the current will not travel a more resistant path? Is the argument over the true definition of star grounding, or just the point that Rick's approach is basically star grounding but the pot's touch the shield, again still not knowing if that causes any harm due to the resistance and the fact the electricity will not follow a more resistive path (I dunno if that's a fact). If that is the case, is true isolation needed for it to be in definition a true star grounded circuit?
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Re: Copper shielding ??

Postby hogan » Tue Oct 05, 2010 7:45 am

Just because somebodies been doing something for 40+ years doesn't mean they can't have their terms confused. Sounds like RT doesn't want to admit that. His way of doing it works, but the process he describes isn't really star grounding. You can argue all you want but it isn't.
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Re: Copper shielding ??

Postby waldo041 » Tue Oct 05, 2010 8:08 am

the 2 points in question are a.) star/signal grounding and b.) shield/ chassis grounding. both are 2 completely different entities, but the problem lies with the fact that they both are connected together. RR's point is that in their interconnection that it is no longer a TRUE star ground. but, imo, Rick is stating they should be looked at for their individual functions.

theoretically, the meeting of signal grounds individually to one fixed point is called Star grounding. the shield should meet at this point with a wire. even though the switches and pots contact the shield, their signal grounds do not at that point. i understand that they actually do and that is my next point. the one part that throws this whole discussion out of wack is the output jack. it's shield or ground lug also touches the shield/chassis ground with contact at installation point and it's also the point where the signal ground makes contact to that contact points lug. SO, if you do not solder a shield wire to the star ground, it still has conduction where the jack meets the shield. so it's function will work. if you don't have a shield then the signal ground only goes out the output jacks shield/ground lug and the shield function does not exist. that i believe we all can agree on. i believe the crux is whether the signal/star grounding can or should be soldered directly to the actual shield(this can construed as star grounding, but is not actually star grounding). i say no, this leaves ONLY the output jack shield/ground lug through hole connection, or contact point where it makes contact with the shield to make contact with the actual shield. if that nut loosens or worse the connection becomes compromised or corroded, then the signal grounding is lost. the very best way is to have 2 conductor shielded wire output where the signal(star) ground and shield(chassis) ground each have there own conductor. shield to shield and signal and signal ground on their own conductors respectively. that said, the shield and signal ground end up meeting down the line anyway. so the next best way, imo, is the way it is traditionally done and that is to have both the signal/star ground AND shield/chassis ground w/ soldered wire, soldered together meeting at the one place out the guitar at the output jacks shield/ground.

just my 2 cents.

peace,
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Re: Copper shielding ??

Postby JonnyBoy » Tue Oct 05, 2010 8:21 am

Rick Turner wrote: I keep shielding ground separate from signal grounds, and I don't loop them.



If that is the case, then what RR and RT are arguing is the same thing. I believe, and could be wrong, that RR was arguing that the pots touching the shield and being connected by wire to buss is creating a loop and not truly isolated. The loop is what RR was saying was not true star grounding if I understand the info correctly. And again, would a loop matter if the shielding side of the loop has a higher resistance at all times, thus being isolated by the laws of electricity?

Waldo, isn't the path to the final point (input jack) the path the electricity wants to go? That being the case, what does it matter how it gets there and if the two(shield and signal) meet up before the final destination where they mix anyway? Wouldn't a loop be more resistance anyway and not matter?
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Re: Copper shielding ??

Postby waldo041 » Tue Oct 05, 2010 9:25 am

the loop is created when a star/buss ground or other grounding scheme is used on a pot casing with shielding. this approach to ground is directly connected to the output jacks ground output lug. but the problem lies in that the same pot case(s) that the signal ground is tied to is directly connected to the output jacks ground lug which is also connected to the shield at it's(their) casing. the shield is also wired directly to the output jacks ground lug. this creates 2 paths to the output jacks ground lug/output or in other words a loop or multiple pathes to ground. what Ray is saying is that the "Star" is not a star because the shield ties to it at the output jack. but the shield needs to be looked at as an individually functioning piece of the equation and not as a path to ground, even though it is. what rick is saying is that all the signal grounds should tie together at one singular point(star) and the singular shield should also tie to that point, the output jacks ground lug.

a stock strat can get away with it's form of shielding and using the pot casings because the shield is not tied to the output jacks ground directly with a wire. it is tied to ground, but rather from the pot casings. this leaves only the one direct path, shield>pot casings>signal ground(star/buss/multiple)>output jack ground lug versus the 2 paths if the shield was wired directly to the output jacks ground lug. then all the pot casing signal ground connections would be loops.


Rick Turner wrote: Then there is the issue of ground loops acting as coils and picking up electromagnetic radiation. This is why you should not loop ground connections from pot to pot to point.



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Re: Copper shielding ??

Postby JonnyBoy » Tue Oct 05, 2010 9:40 am

I see, Thanks. But I still don't understand, even if there are two paths (connecting at the pot/shielding and at a wire/buss), the current will only flow down the one with least resistance, so the higher resistance connection is as if it is not there at all anyway because it won't travel down both if one has less resistance, true? That is if the pot to shielding connection is a higher resistance than the wire coming off of it to the buss. And if that was true, there would be no need to insulate the pot from the shielding? Just wondering and really don't know if that is true.
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Re: Copper shielding ??

Postby waldo041 » Tue Oct 05, 2010 10:13 am

JonnyBoy wrote:I see, Thanks. But I still don't understand, even if there are two paths (connecting at the pot/shielding and at a wire/buss), the current will only flow down the one with least resistance, so the higher resistance connection is as if it is not there at all anyway because it won't travel down both if one has less resistance, true? That is if the pot to shielding connection is a higher resistance than the wire coming off of it to the buss. And if that was true, there would be no need to insulate the pot from the shielding? Just wondering and really don't know if that is true.


no, the current will flow down both paths, this is what creates the problem.

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Re: Copper shielding ??

Postby TI4-1009 » Tue Oct 05, 2010 6:11 pm

Um, River Rat- with all due respect, you do know who you're arguing with, right???
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