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Old 1st February 2004, 11:07 AM   #1
Prune is offline Prune  Canada
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Default Shielding interconnects

I've seen cables that, instead of foil and braid shielding, use just foil along with a drain wire wrapped around to provide lower resistance to ground. Is this significantly less effective than shield and braid? If I use the drain wire method, do I wrap it in the same direction as the twist of the signal carrying wires inside, or opposite?
I plan to use double shielding (insulation in between), which deals with both electrostatic and electromagnetic interference. If I use braid, is it effective to only use as one of the shields and foil for the other, and then which one, the outer or inner?
Jon Risch from audioasylum recommends only grounding source end of the shield and terminating the other end with 0.01uF to ground. In my case of two mutually insulated shields, does this apply to both shields?
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Old 1st February 2004, 12:13 PM   #2
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take a look at this for some reading>>> http://www.rane.com/note110.html
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Old 1st February 2004, 12:29 PM   #3
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I'm familiar with that document, but it doesn't deal with my questions.
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Old 1st February 2004, 12:42 PM   #4
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I use double sheilded twisted pair cable and both of the sheilds are connected together
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Old 1st February 2004, 12:53 PM   #5
dimitri is offline dimitri  United States
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>double shielding (insulation in between), which deals with both electrostatic and electromagnetic interference

sorry this is nonsence

>Jon Risch from audioasylum recommends only grounding source end of the shield and terminating the other end with 0.01uF to ground

you can ask Mr.Risch in person, but this is diyaudio, not audioasylum

the common way - shielded twisted pair, with shield connected to ground in the input plug
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Old 1st February 2004, 12:58 PM   #6
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well it seems to me you have an answer to your question already.....alot pertains to the system that the interconnects are in......for my system this works....maybe for your application something else is better suited
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Old 1st February 2004, 01:13 PM   #7
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Quote:
Originally posted by dimitri
sorry this is nonsence
I worded it badly, and my example was mistaken. But two mutually insulated shields and capacitors are used professionally. Take a look for example here (and similar information can be found in other places), under the section "Shield connection":
http://www3.phoenixcontact.com/cgi-b...oersicher.html

So, restating that one of my questions, assuming I wire as in figure 4 (except the inner is grounded at the source end), is it OK to use foil instead of braid for one of the two shields, and which one?
My other question about how foil+drain wire compares to shielding braid remains.

Quote:
this is diyaudio, not audioasylum
So? What's your problem? Get up on the wrong side of the bed today?

Quote:
the common way - shielded twisted pair
I was asking for a comparison of what sounds best, not which way is the most common. All three I mentioned are used in various audio cables.
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Old 1st February 2004, 01:37 PM   #8
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Use triple shielded cabel : Connect ( from middle to up ) middle - hot, first shielding - ground, second shielding - ground on one end of cable, third shielding - ground on second end of cable.
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Old 1st February 2004, 02:35 PM   #9
dimitri is offline dimitri  United States
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>double shielding (insulation in between), which deals with both electrostatic and
electromagnetic interference

double shielding deals _only_ with electrostatic interference, twisted pair helps you do suppress electromagnetic interference. The better is four twisted wires (1-2-3-4), where two wires (1&3) and other two wires (2&4) connected in parallel.

>… is common practice to connect one side to the reference potential via a capacitor. This interrupts the ground loop for direct or low-frequent currents at least.

In this case all the hf EMI (from mobiles, etc) will be yours

For the good start try jensen transformer site and Bill Whitlock publications

>is it OK to use foil instead of braid for one of the two shields
it is better to use foil and thin braid simultaneously (as one shield)

>So? What's your problem? Get up on the wrong side of the bed today?
Not exactly. Nothing personal, sorry. But the discussion of the sound of two-feet double shield cable with a battery between the shields, or the cap before and after stripping from copper can drive me mad.

In different installations I worked with snakes thousands feet long, at mV levels with presence of strong EMI. The correct way of grounding and shielding in this case can be obtained only when you understand how the grounding actually was made in each piece of equipment on both sides.

>I was asking for a comparison of what sounds best
you have already know the answer – it’s up to you:
>Religion is answers that may never be questioned
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Old 1st February 2004, 02:49 PM   #10
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Let me see if I understand you correctly: you recommend to use a twisted quad and a single foil-braid shield grounded at the source end.

Now I have a couple more questions:
Assuming a ground loop does not occur, could it be better to ground both ends of the cable?
And if I can't find large diameter braid (which I can't) is the foil+drain wire much worse?
What gauge is best to use for signal conductors (I'm using copper litz wire)? I have about 21; do I need thinner or thicker for interconnects?
How far does the shield need to be spaced away from the conductors, and what to use as a spacer?

Thanks in advance for replies.

PS
Quote:
cable with a battery between the shields
Say what?
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