views on shielded cables?

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JP78

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views on shielded cables?
« on: 15 Dec 2013, 05:02 am »
I'm familiar with Frank's views on expensive cabling, IEC cables, etc, but as an engineer whose opinion I respect very much I'd like to get some thoughts on the impact / importance of shielding versus not.

I also understand if there is microwave-level RF then shielding will of course improve, but I'm worried more about the average person's room.

If you could shed some light on the importance of shielding at the speaker wire, interconnect, power cable levels I'd really appreciate it.  Should this matter between connector types, or in the case of interconnects, XLR vs RCA? Apologies if any of these questions are ignorant.

Best,

WireNut

Re: views on shielded cables?
« Reply #1 on: 15 Dec 2013, 06:33 am »
FWIW,
I built 4 DIY XLR interconnects with Neotech solid core UPOCC copper in Teflon (no shield) in a 3 wire braid and hated them.
Replaced them with Belden 89207 cable (has a shield) in a DIY XLR interconnect and love them.



 









 




 

dB Cooper

Re: views on shielded cables?
« Reply #2 on: 15 Dec 2013, 11:34 am »
Frank's views on he topic of shielding are discussed in detail in his old "Audio Basics" newsletter which is downloadable from his website. Hope he won't mind a brief quote:
"Some golden ears recommend the use of non-shielded wire for interconnects 'unless you have RFI in your area.' We offer a simple test for RFI: A. Turn on your radio or TV. B. Does it work? C. If so, congratulations, you have RFI in your area. D0 NOT use unshielded interconnect cables."
« Last Edit: 15 Dec 2013, 12:41 pm by dB Cooper »

Photon46

Re: views on shielded cables?
« Reply #3 on: 15 Dec 2013, 01:36 pm »
I run ten feet of unshielded Luminous Synchestra Reference interconnects from my phono preamp to my preamp and have no-nada-zero problems with RFI interference, hum, or any problems (all other interconnects in my system are the same Luminous wire.) I don't care whether you are a cable objectivist or subjectivist, there is no one size fits all answer to questions of cabling. All of our ears, brains that process our ear's signals, and audio systems are different. If your system isn't highly resolving, you probably won't hear a difference between good shielded and unshielded wires. If you have a system that reproduces the upper frequencies on the "hot" and lively side of the spectrum, you may well not like unshielded. If you listen to nothing but energetic mixes of rock n roll and other popular music, you may not like unshielded. The differences are subtle, things like the decay of triangles and cymbals in orchestral music are more delicate and well resolved with unshielded wires (in my system.) If you want to decide for yourself, just buy a used set of unshielded wire you can resell for little or no loss or spend an afternoon making these: http://www.soundstage.com/synergize/synergize021998.htm  Many forum participants know I've recommended these more than once and I've received a number of private messages from Audiocircle readers that made these and thanked me for the heads up on great sounding cheap interconnects.

Please remember boys and girls, this is supposed to be a fun hobby, not a theological debate. Before this thread runs its course, there will be pro and con responses of every kind. These sort of discussions almost always degenerate into nasty snipping about the inability of someone to perceive reality, being subject to audio industry sponsored consumer mass hypnosis, etc. There's no need for it. For something this inexpensive, listeners can just try it both ways and decide for themselves.

avahifi

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Re: views on shielded cables?
« Reply #4 on: 15 Dec 2013, 01:38 pm »
Right now I am using and recommend BlueJeans cables.

http://www.bluejeanscable.com/store/audio/index.htm

They are very low capacitance, very well shielded, and have excellent quality termination fittings.  I use their speaker cables too terminated in their locking banana plugs.

Safe, easy to use, and durable, and rationally low priced to boot.

Frank Van Alstine

PSB Guy

Re: views on shielded cables?
« Reply #5 on: 15 Dec 2013, 03:15 pm »
The Blue Jeans website also has some excellent articles about the science behind their cable choices among  other relevant subjects.

Cornelis

JP78

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Re: views on shielded cables?
« Reply #6 on: 15 Dec 2013, 06:38 pm »
Thanks Frank. I'll get my hands on some and see how they fit.

AluminatiSound

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Re: views on shielded cables?
« Reply #7 on: 15 Dec 2013, 06:59 pm »
I run them. They can be found for very cheap with or without a shield :)

Best,
Matt

Speedskater

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Re: views on shielded cables?
« Reply #8 on: 15 Dec 2013, 08:41 pm »
When someone writes about using unshielded RCA interconnects it reminds me of when we tell the grandchildren to buckle the car's seat-belts and they respond that they didn't buckle them yesterday and nothing bad happened. It's just a matter of time. 

Speedskater

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Re: views on shielded cables?
« Reply #9 on: 15 Dec 2013, 08:44 pm »
A 3 wire braid makes a very poor XLR balanced interconnect.  You need to read about 'Shield Current Induced Noise' (SCIN).

http://www.audiosystemsgroup.com/Shield_Current_Induced_Noise.pdf
http://www.audiosystemsgroup.com/SCIN-2.pdf

Elizabeth

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Re: views on shielded cables?
« Reply #10 on: 15 Dec 2013, 11:33 pm »
When someone writes about using unshielded RCA interconnects it reminds me of when we tell the grandchildren to buckle the car's seat-belts and they respond that they didn't buckle them yesterday and nothing bad happened. It's just a matter of time.
Yeah, but when your unshielded cable gets a problem you can just swap it for some other. No problem. Not Rocket Science.
 when you kid needed the seatbelt and did not use it.. way too late.

R Swerdlow

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Re: views on shielded cables?
« Reply #11 on: 16 Dec 2013, 03:13 pm »
If you could shed some light on the importance of shielding at the speaker wire, interconnect, power cable levels I'd really appreciate it.  Should this matter between connector types, or in the case of interconnects, XLR vs RCA?

To understand whether or not shielding is needed, consider the voltage levels in the various cables.  They are not all the same, and the lower the voltage level, the more you need shielding.

Phonograph Level
     moving coil 0.5 millivolts (mV)
     moving magnet 4-5 mV

Line Level
     about 100 mV (0.1 volts)

Preamp Level
    varies from about 0.1 to 10 volts

Speaker Level
    varies from about 1 to 100 volts

Most EMI and RFI is on the weaker side, in the ball park of millivolts or less.  But that can vary depending on your local conditions.

So it makes sense to use shielded cables that carry the weaker signals: phonographs, line level signal sources (DVD, Blue Ray, CD, TV sets or cable boxes, etc.), and preamps.  For the same reason, it usually works better to keep these cables as short as possible.

Speaker level signals are significantly stronger that most sources of EMI/RFI.  As a result, speaker cables, in nearly all cases, don't require shielding.

If signal levels are low enough to need shielded cable, then use shielded cable no matter what the connector type, RCA or XLR.

Charles Calkins

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Re: views on shielded cables?
« Reply #12 on: 16 Dec 2013, 05:27 pm »
I've been using blue jeans cables for years. Before them I had some hum(?)in my audio system. All gone now thanks to blue jeans cables.

                                                                  Charlie

jonbee

Re: views on shielded cables?
« Reply #13 on: 16 Dec 2013, 05:41 pm »
I think there are local variables at work here.
I used a pair of unshielded Cerious ICs for a while. I like their sound a lot, but in my main system switching to them brought a buzz that was pretty audible. My main system has tons of wiring, a cable box, an HT PC, DAC etc., and I live in a downtown location near some radio transmitters. Probably a worse case situation. I wrapped the ICs in copper foil (bought through Amazon) and it reduced the buzz by maybe 80% to a barely acceptable level.
I moved the ICs to my home office system, and the buzz was reduced further -now it was barely audible with the copper foil in place. I've since replaced them with shielded cables, and have no noise issues.
I didn't notice any ill affects from the copper shields, although it was obvious many ICs have much more effective shielding than the copper foil.
Some maintain that lower levels of induced noise is a bad thing and shielding is essential, others believe shielding causes harm. Maybe both are right, in the right application. I also think the signal level, as R Swerdlow has noted, has a real bearing on the audibility of this noise.
In technical applications, such as mixing and mastering, it is always best to keep noise levels as low as possible, but for playback for pleasure, since each installation has its own particulars, trusting you own ears and judgement is a good course.

rollo

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Re: views on shielded cables?
« Reply #14 on: 16 Dec 2013, 06:19 pm »
  Back in the day lots of Aluminum foil was in heavy use for phono cables.


charles

yeldarb

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Re: views on shielded cables?
« Reply #15 on: 17 Dec 2013, 02:32 am »
I have homemade ICs on both my CD player and my DVD.  Cat 5E  PTFE plenum cable.  I pulled out matching twist pairs and soldered up some cheap crap rca plugs.  Sounds fine, no noise detected.  I will add that I am driving a SEP tube amp with the DVD.  I had previously hooked up with a good quality shielded interconnect.  Then, the tube amp, which has no preamp, was flat and really needed a pre.  With the Cat 5E the little amp sounds great.  And it might not work for you.  The noise the amp makes probably exceeds anything picked up by the cable.

There are some really unusual DIY cables on TNT-Audio.

dlparker

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Re: views on shielded cables?
« Reply #16 on: 17 Dec 2013, 06:48 pm »
I think there are local variables at work here.
...

I think that's the key. How about a shielded room, with DC replacing AC where theoretically possible? I'm sure it's been tried and no doubt someone's published the results. For someone with a grasp of the ALL the physics involved, there's no end of tweaks and solutions to problems measured or perceived.

Listening to music is another matter entirely. I recently had the opportunity to listen to a 'state of the art' system from around the WWI era. You could hear the music. It was very similar to the one at my grandmother's house in the fancy cabinet with the green felt turntable and the two drawers filled with those old thick platters. I wore 'em out.

My current AVA-based system is the best I've ever owned, and some of the pieces I'm currently using are several years old. I have none of the current models. The newest is an Insight+ power amp. Each step up is a revelation, but the object is to hear music. Each time I upgrade a component there's a period of evaluation where I want to hear how such and such piece/artist/arrangement/mix sounds with the new component. At some point I always go back to listening to music. I'll always WANT to upgrade and tweak, but..

Minn Mark

Re: views on shielded cables?
« Reply #17 on: 17 Dec 2013, 09:06 pm »
@dlparker  +1   8)

I too, use blue jeans ICs and am very happy with them. I have some new and not so new AVA equipment. Most recently spun some LPs from the set: Fleetwood Mac Live at the Boston Tea Party 1970, using the new Vision phono circuits in my Insight+ preamp. A Wondrous experience.   

It's about the music.

M

Devil Doc

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Re: views on shielded cables?
« Reply #18 on: 17 Dec 2013, 09:32 pm »
Most component manufacturers no longer recommend a cable. They refer you to your dealer. I wonder why? Mr. Van Alstine does in fact recommend BJ cables. Now why would he recommend a cable that didn't show his components in the best possible light?

Doc