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Outer add on shielding

post #1 of 16
1/28/09 at 12:28am
Thread Starter 
Hello,
I guess this could be a tweak so here goes-
I have an interconnect that is litz braided and inside of teflon tubes and I use it by my computer so I was wondering if there would be any benefit from wrapping it in aluminum foil. It may sound a bit silly, but there isnt any shielding and though I am not hearing any interference, it may make a difference to put a layer around it as a bit of interference rejection. Any benefits or negatives to wrapping it in aluminum foil?

I will likely try this tomorrow and report back with my findings, but I was just curious if anyone else has done this as a simple r.f.i. shield.

Dave
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post #2 of 16
1/28/09 at 2:16am
Shielding will help a lot. Can you find some braided metal tubing, that would work well. Alum Foil would be a good experiment. You could add a drain wire (connected at one end) cover it, then run it through a braided shield and then cover it with technoflex or nylon.
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post #3 of 16
1/28/09 at 2:21am
A litz braid also naturally rejects interference -- that's the whole point. If you're not picking up, why bother?
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post #4 of 16
1/28/09 at 2:25am
Quote:
Originally Posted by Sherwood View Post
A litz braid also naturally rejects interference -- that's the whole point. If you're not picking up, why bother?
Point is I had a Litz cable and it was noisey as hell, it was made by a respected cable builder here too, not some DIY stuff. So from that experience I came to the conclusion that there is more to it than Litz.
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post #5 of 16
1/28/09 at 2:31am
Thread Starter 
Quote:
Originally Posted by Sherwood View Post
A litz braid also naturally rejects interference -- that's the whole point. If you're not picking up, why bother?
I was under the impression the litz braid was meant to overcome the skin effect more than anything else.

I actually just did a bit of an experiment, where I covered my cell phone in aluminum foil (a solid piece) and it dropped to 1 bar from 5 bars (its an iphone, I had to make a little tab where i could lift up to check but it has a slow refresh rate) and it dropped from my wifi to edge. Bluetooth was still able to go through albeit staticky. So from that I gather that it can effectively block out wireless signals (g or n from my router). I also gather that it has some effect on cell signals.

I also did wrap my litz braid IC in foil and hooked it back up and I'll be darned to say it doesnt sound quieter. Somethin about it sounds a bit cleaner. Believe me not night and day, and I hate to say that wrapping something in aluminum foil would change anything, but I cannot refuse that it does sound a tab bit different. Possibly placebo, but it just sounds a little cleaner/darker I guess in quiet passages. Could also be that my phone is also wrapped up right now.

I'd appreciate if someone else tried it on a non shielded IC and shared their experience.

Dave
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post #6 of 16
1/28/09 at 2:50am
Anyone using a computer for a transport and or has a bunch of wires shoved into a tight place and doesnt have a shielded cable is screwing the pooch.
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post #7 of 16
1/28/09 at 2:55am
Thread Starter 
Quote:
Originally Posted by olblueyez View Post
Anyone using a computer for a transport and or has a bunch of wires shoved into a tight place and doesnt have a shielded cable is screwing the pooch.
xD, thank you.

I was also under the impression that the litz was supposed to throw off interference before some reading, now its my understanding that it is to overcome the skin effect and proximity effect.

I'm going to have to say that I think such a simple fix as wrapping the IC in foil made a small improvement in cleanliness of the signal. Bout time I covered her shame hah. I'm going to leave the "shielding" on for a few days and see how my ears like it.

Eager for someone else to try!

Dave
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post #8 of 16
1/28/09 at 2:59am
Thread Starter 
A thought just occured to me, what is the downside to internal shielding? There must be one or all cables would be shielded right?

Seems more logical to place the shielding around the outside of the conductor, dielectric, and insulation if it is going to be moving charges and possibly attracting electrons right?

so in other words put the conductor-> dielectric -> insulation-> shielding-> insulation and one may have a better cable than shielding around the dielectric inside of the single layer of insulation. However at the cost of flexibility and labor.

EDIT - woops just realized thats how the majority are set up lol But there must be a downside to shielding, possibly its the conductance and possibility of holding a charge in the shield, where a drain wire would be used. However there shouldn't be that many amperes running through an audio IC right? is it sherely the flexibility that is the problem?

Dave
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post #9 of 16
1/28/09 at 3:07am
Quote:
Originally Posted by myinitialsaredac View Post
A thought just occured to me, what is the downside to internal shielding? There must be one or all cables would be shielded right?

Seems more logical to place the shielding around the outside of the conductor, dielectric, and insulation if it is going to be moving charges and possibly attracting electrons right?

so in other words put the conductor-> dielectric -> insulation-> shielding-> insulation and one may have a better cable than shielding around the dielectric inside of the single layer of insulation. However at the cost of flexibility and labor.

EDIT - woops just realized thats how the majority are set up lol But there must be a downside to shielding, possibly its the conductance and possibility of holding a charge in the shield, where a drain wire would be used. However there shouldn't be that many amperes running through an audio IC right? is it sherely the flexibility that is the problem?

Dave
I think the Kimber Kable website may have some answers for you, they dont use shielding.
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post #10 of 16
1/28/09 at 4:52am
Quote:
Originally Posted by myinitialsaredac View Post
A thought just occured to me, what is the downside to internal shielding? There must be one or all cables would be shielded right?

Seems more logical to place the shielding around the outside of the conductor, dielectric, and insulation if it is going to be moving charges and possibly attracting electrons right?

so in other words put the conductor-> dielectric -> insulation-> shielding-> insulation and one may have a better cable than shielding around the dielectric inside of the single layer of insulation. However at the cost of flexibility and labor.

EDIT - woops just realized thats how the majority are set up lol But there must be a downside to shielding, possibly its the conductance and possibility of holding a charge in the shield, where a drain wire would be used. However there shouldn't be that many amperes running through an audio IC right? is it sherely the flexibility that is the problem?

Dave
Increased capacitance.
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post #11 of 16
1/28/09 at 10:42am
Thread Starter 
Quote:
Originally Posted by NightOwl View Post
Increased capacitance.
Ahh. Wouldn't that also be an inherent problem with the litz braid as well as shielding? Likely not a good combo to shield?

Dave
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post #12 of 16
1/28/09 at 5:15pm
Quote:
Originally Posted by myinitialsaredac View Post
Ahh. Wouldn't that also be an inherent problem with the litz braid as well as shielding? Likely not a good combo to shield?

Dave
Depends on the number of strands, gauge of the wire , geometry of braid, spacing between strands (less is better), spacing between conductors and shield, dielectric material, etc. But, yes, a litz braid has inherently higher capacitance than a simple twisted pair or coaxial design.
There is a simple overview of cable construction with pros and cons at George Cardas site.

Cardas Audio

There is also a link below to Jon Risch's web site. I don't necessarily agree with all his conclusions, but he's probably spent as much time as anyone on the planet studying audio cables.

Jon_Risch's Web Site, Cable Main Page

If you're interested in cables, they're both good reads.
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post #13 of 16
1/28/09 at 5:54pm
I don't know why but I didn't shield my interconnects. Should I bother?
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post #14 of 16
1/28/09 at 5:58pm
Thread Starter 
Quote:
Originally Posted by apatN View Post
I don't know why but I didn't shield my interconnects. Should I bother?
Give it a try with some foil and let us know what you think.

Dave
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post #15 of 16
1/28/09 at 7:50pm
Quote:
Originally Posted by apatN View Post
I don't know why but I didn't shield my interconnects. Should I bother?
Depends on your environment, your cable construction and your sound preferences. If your cables are braided, this geometry provides some RF and EMI rejection, but not as much as a full shield. THE FOLLOWING ARE GENERALITIES as there's a lot more to the "science" of cable construction. Unshielded cables can pass a "purer" signal than shielded cables, but RF and EMI can more than offset this. If your conductor consists of more than 2 braided wires per conductor, you are increasing capacitance (as you are by adding a shield). High capacitance will normally manifest itself as a "warm" sound signature with less treble energy. The two most common and "safest" cable designs are two braided insulated wires per conductor with a double overall shield (twisted pair with shield for analogue) and one straight wire per conducter with overall shield (coaxial for digital).
With the proliferation of electronics in today's world I always recommend a shielded cable, but if you are in a relatively "noise" free environment, you may prefer unshielded.
There are many cable designs and they are all a compromise of some kind. There are variations in materials, geometry and size. Unless you have a specific requirement (capacitative loading, minimum or maximum inductance etc.) they can all sound good or bad. There's no one right way.
Shields also have electronic properties and materials and geometry can affect these also. A foil shield is the most basic of all, but also has downsides.
If you are going to shield your interconnects and they are braids, tie the shield to ground only at the source end so that the shield doesn't become part of the signal path. This is the real reason for directional cables as opposed to those cable makers who tout the directional nature of the cable material's grain structure (bs).
End of Rant.
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