Shielded or braided better? - Head-Fi: Covering Headphones, Earphones and Portable Audio

greggf · 05-31-2008, 11:40 PM

Can anybody tell me whether shielded interconnect cables - with foil or whatever - is better when it comes to EMI/RFI rejection (or whatever it's called), or whether an unshielded braided type will do just as well?

Is there any superiority for either type, in either theory or in practice?

Or are there just too many variables to make a judgment, just as it's possible to have bad sounding opamp-based headphone amps, and really good sounding opamp-based ones, depending upon the implementation?

Uncle Erik · 05-31-2008, 11:44 PM

Depends on how much RFI there is. If you're next to a 10kW transmitter, shielding won't do that much good. But if there's no/little RFI, then it won't matter whether the cable is shielded.

If you have a moderate amount of RFI, say from an electric fan, dimmer switch, cell phone, fluorescent light, etc., then a shielded cable is what you want to use.

No matter the topology of the wire (braided, stranded, solid, et al.) it will act an an antenna and pick up RF if it is not shielded.

Also, if you're set on using braided wire, you can can still put shielding over it. It'll be a little more work, but you'll be able to have a braided cable with shielding if you want that.

greggf · 06-01-2008, 01:31 AM

I'm in a very rural area, alongside a state forest.

But the listening room, and the whole house, is full of dimmer switches.

I assume shielded is the way to go?

AND . . . can you or anyone else recommend cables that seem to have good shielding properties? (The less expensive, the better, of course.)

Hardflip · 06-01-2008, 03:36 AM

I would definitely look at Blue Jeans Cables. I got their Digital coax and it is beautiful sounding. Brought out some more detail over the previous cable.

Their LC-1 rca cable looks real nice, too. I may just pick one up to see how it fairs. Very reasonable prices as well

PhaedrusX · 06-01-2008, 04:44 AM

Originally Posted by Uncle Erik

...No matter the topology of the wire (braided, stranded, solid, et al.) it will act an an antenna and pick up RF if it is not shielded.

Also, if you're set on using braided wire, you can can still put shielding over it. It'll be a little more work, but you'll be able to have a braided cable with shielding if you want that.

i'm mulling over using a four-strand shielded cable or an unshielded three-strand braid.

with the four-strand cable, does the shield need to be tied to ground on one end? i've read of some DIYers doing this, while others just snip off the exposed shield and use the four wires. I'm curious how big the benefit is when the shield is grounded.

regarding the braid, if a shield was added, again would it be required to tie it to ground on one end only?

nikongod · 06-01-2008, 05:07 AM

The cardas DIY cables have shields. on the less expensive fronts, I would look at markertek in their wire sections.

An ungrounded shield has nowhere near the protection value that a grounded one has. The question is not whether to ground it but where and how. one RCA, both RCA's, or a separate ground.

edited: I assume you are refering to a star-quad by 4-wire with shield. 2-wires twisted should give lower capacitance pr length, which is very good for cables. the 2-conductor cables may turn out less expensive too.

It sounds crazy on first hearing, but I have seen recommendations for a shielded POWER cable. The argument for it kind of makes sense: as much noise as a rectifier makes is reflected back through the power transformer. this noise can extend into low RF, and a shield can do as much to contain noise as keep it out...

Punnisher · 06-01-2008, 05:26 AM

What I do, is use a 4 conductor wire + shield, and tie a separate wire to the braided shield itself. Ten you attach that to the chassis of whatever your connecting it to.

PhaedrusX · 06-01-2008, 05:55 AM

Originally Posted by nikongod

...An ungrounded shield has nowhere near the protection value that a grounded one has. The question is not whether to ground it but where and how. one RCA, both RCA's, or a separate ground.

edited: I assume you are refering to a star-quad by 4-wire with shield. 2-wires twisted should give lower capacitance pr length, which is very good for cables. the 2-conductor cables may turn out less expensive too...

righteo...a grounded shield it is then.

yes, i was referring to a starquad cable, but the ones i've seen have all four wires twisted together rather than twisted pairs. curious if that nullifies any benefit of lower capacitance that you mention.

i looked at some two-strand cables but was concerned that the thicker guage wire might compromise flexibility since i'm looking to make short "U" shaped interconnects for stacked components.

PhaedrusX · 06-01-2008, 06:02 AM

Originally Posted by Punnisher

What I do, is use a 4 conductor wire + shield, and tie a separate wire to the braided shield itself. Ten you attach that to the chassis of whatever your connecting it to.

hmm...if i understand this correctly you would have a separate wire dangling outside the connector?
since my source is housed in a wooden enclosure i don't think this would be feasible, but i'm wondering how you attach the wire to a metal chassis.

infinitesymphony · 06-01-2008, 11:38 AM

Copper braid and aluminum foil are two common types of shield. You'll want shielded cables for all line-level interconnects--there are no trade-offs, only benefits.

I'd go with Blue Jeans Cable if you're interested in pre-built cables, or at least use their cable and connector choices as references. If you want truly high-quality RCA cables, go with BJC LC-1s--they simply can't be DIY'd as well as BJC makes them, since the connector is crimp-style (better than soldering) and requires crimping machines to do properly.

If you're building a specific type of cable, we can give you more recommendations about models and connectors.

Also, the question "where do I connect the shield" is a pretty complicated one that varies depending on the cable type, what your equipment expects, and even your own stance on where ground loop prevention should occur. I connect the shield/ground on both ends (signal ground). Punnisher's solution is great because it uses chassis ground versus signal ground. Other people only ground the cable at one end to prevent any grounding from occurring, but this can cause some equipment to malfunction (and shouldn't make any difference if all of your equipment is properly grounded).