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Why would anyone use unshielded cables? Seems that power cords are touted as being important because of all the RFI around. Would not all cables pick up unwanted stray signals of all types? What could be gained with unshielded cables? I am sure I am missing something here.
Follow Ups:
I see that its a good idea to get a shielded power cable for a computer that is in the same room as the sound system. But do I need one if I never have the computer "turned on"? Or is the power supply still sending digital nasties into the power lines.
_______________________________________*Analog fans may be blind-but digital fans are deaf*
http://www.flickr.com/photos/82495693@N00/
HowdyThese days computers, like most remote controllable devices, are often a "little" on. (My computer actually came with a remote which has a power button... :) There is a small amount of power being supplied so that various devices (your modem, network, keyboard, USB, etc.) can wake your computer up... Since this power is being supplied by your computer's switching power supply, there probably is a little junk being put back on your power lines, but probably not nearly as much as when the computer is going full bore...
Hi.Let me give you an example, a certain brandname LAN cable, Cat 5e & cat 6, with 4 pairs of insulated solid conductors jam-packed inside the jacket, yet are claimed to deliver up to 350MHz frequency response WIHTOUT any shielding!
Such extended high-end response is needed for ultra fast data transfer. How? The manufacturer claims a special twisting technology is used to achieve such high speed transfer without using any shielding there to slow down the speedy transfer.
Same principle can also apply to audio cables. As long as the pair of IC is built up of two wires of IDENTICAL size & material & construction, one serving as signal in & the other wire as signal return, they are twisted together tighly & UNIFORMLY. Any EMI/RFI noises generated on one turn will be cancelled out in the next turn.
So no shielding should be needed. Don't overlook shielding is sorta
kinda sweet poison with shielding-to-conductors capacitance which drain off the high frequencies of the audio signals. Don't use it unless your gears are in some EMI/RFI noisy environments.All the ICs & power cords I built for own use & for my audiophiles friends are built WITHOUT any shielding.
I snap on EMI/RFI ferrous suppressor ring only on the power cord of my switch mode power supply for my phonostage tube heaters. No shielding for my power cords at all.
c-J
From a purist POV, the use of shielding is often considered by some folks to be a necessary evil; a design compromise that's only necessary if audible noise issues occur within a particular audio system located in a noise prone area. The notion is: When an unshielded line-level interconnect cable designed with an effective noise canceling/rejecting geometry is used in a moderate RFI/EMI area, and kept well away from adjacent AC power cords that emit noise, shielding is thought to be unneeded and to only do harm to the signal (phono-level interconnect cables and digital/video coaxial cables excluded).Here's some info from XLO, well known for their line-level interconnect cable model versions available as shielded or unshielded:
http://search.globalspec.com/Search/viewcache?query= shielding speaker&doc=264341472651&SrchItem=5
-snip-
"...A note on shielding... shielding affects the sound. Even shielding done
the right way (which is the only way that XLO will ever do it) acts like an
additional capacitor, and creates "dump artifacts" that will audibly change
the sound of the system. Done the way XLO does it (with insulated
over-shielding spaced as far as possible from the signal conductors and
grounded outside the signal path) the sonic effect of shielding is minimal.
Even so, to the critical listener, it may still be audible, if only very
slightly. XLO recommends that, for the very finest systems, shielding for
line level interconnects should not be used unless severe EMI or RFI
problems make it necessary. If you must use it, though, use it. It's far
better to deal with tiny incremental shielding losses than with large
annoying hum, noise and static problems. The proof? All of XLO's phono
cables (even the Signature2 Type 3.2 ) are shielded, and the critics still
regard them as "The Best in the World."..."-snip-
I will add that the same notion applies to AC power cords. However, a digital component tends to produce digital noise that can enter an audio/video system via the digital component's power cord, so much as to pollute adjacent components (radiated noise emission) and the AC delivery system (line-borne noise). Thus said, shielded power cords intended for digital components are often welcomed, since the shielding action is more that of noise suppression rather than noise rejection -- meaning a shielded power cord does more good in protecting adjacent gear from digital noise rather than of direct benefit to the digital component that it's connected to. The use of AC filtering methods such as isolation, noise cancellation, and capactor-based power line conditioning (including the Auricap Tweak) do well to protect adjacent gear from line-borne digital noise.
So, other than the want of shielded power cords for use on digital components, many folks have found that shielded power cords tend to restrict dynamics and negatively affect soundstaging and other listening cues when placed on analog components. Self-shielding designs such as star-quad and high twist ratio helical geometry power cords are often found to be more desirable for analog use, both high current amplification and low power source components, alike.
HowdyWell, they can sound better. I have a balanced system with balanced components and good grounding. My components have low output impedance. My interconnects are approx 1m and my speaker wire 8'. In my system I don't like the closed in sound from shielded cables.
I'm sure that some people have more RFI than I do (and others less) and hence they may make different trade offs.
There is nothing magic about shielded cable. The shield is a conductor, and can support RF resonances just like any other conductor in the cable. In fact, there will be resonance modes among all the conductors, including the shield.Getting a shielded cable to sound good requires that the resonance issues be addressed. Simply grounding the shield is not the answer. Sorry that I can't go into details beyond this observation, as the answer is proprietary technology that does not belong to me.
IMHO, blocking RFI not the only (or the main) reason for using an aftermarket power cord.My take on the conventional wisdom is that power cords for digital components like CDPs benefit from shielding due the smaller current draw. The RFI ingress can play havoc with the circuitry and have a noticeable impact on the sound. Same reason why interconnects are shielded.
Bear in mind that the shield, if not properly designed, could have a negative impact on the sound itself, which is why some people prefer unshielded ICs. Personally, having tried unshielded ICs, I prefer shielded in my setup.
Power cords for analog components like pre-amps and amps benefit less from shielding, due to the current draw being higher. The effect of RFI ingress on the sound is minimal, relatively speaking. This is the same reason why most speaker cables are unshielded.
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There's an opportunity: we start selling shielded speaker cables and tell the world it's the only way to go!
You may try your luck, but I wouldn't hold my breath.IMHO, audiophiles who spend $$$ on cables usually would like to audition them before buying. Shielding on speaker cables is said to quash dynamics, that's why other methods of noise canecellation are preferred, like for example the "star quad" configuration or other winding geometries.
BTW, Furutech makes some shielded speaker cables. They might make a noticeable difference in high-sensitivity speakers.
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