Great Article on Cables

[Monstrous Mike]

Obviously, that is incorrect given the presence of shielding in a wide range of cables. Here is one of the times I directed this question to you where you did not respond:

Sighted Testing IS King!! Silly me - all those years wasted...

So what is the missing metric? rw

Since I'm on a roll, here is something for you to read: http://www.floemc.com/applications/s...ness/index.jsp

In general, Belden doesn't give any shielding data because shielding effectiveness very much depends on the installation of the cable, the connectors, the length, the environment, the equipement connected, etc. It would be impossible for Belden to come up with data for all of the scenarios their customers use for their cabling. Shielding is not a cable metric, it is measure of protection for the signal in a given environment.

And actual shielding effectivene testing is quite complicated and expensive. When it does happen, it is usually tested for a specific purpose. For example, on our naval vessels, there are several high power emitters like radar, fire control radar, HF communications, etc. So we have done a thorough shielding effectiveness test (usually before a ship is first commissioned and then only infrequently after that) by simulating the actual shipboard radiation it will be exposed to and having all sensitive electronic equipment operational. This is a tedious and expensive process.

During the normal life of a ship, cables and equipment are designed to meet military standands with some manufacturer's testing. Mostly, equipment problems at sea are tackled with troubleshooting and if EMI is the culprit, then measures are taken to eliminate the problem.

I guess an analogy would be designing a skyscraper. You obviously need to consider hurricanes and earthquakes when you design the structure (thickness of steel, use of cement, flexibility points, etc.) but you don't actually do tests on a completed building.

As for pertinent facts, how does Motorola determine how much shielding is required for a given component? rw

Motorola would analyze the range of envirnments the product is expected to operate in and then apply current good engineering practices regarding shielding. They may even do some testing to verify that the shielding is adequate. Sometimes the customer has special requirements which it can identify and Motorola will provide custom shielding (at a higher cost of course).

[E-Stat]

Shielding is not a cable metric, it is measure of protection for the signal in a given environment.

And a very desirable performance parameter as it can lower the noise floor. Would you buy a tire that is NOT resistant to hydroplaning?

I guess an analogy would be designing a skyscraper. You obviously need to consider hurricanes and earthquakes when you design the structure (thickness of steel, use of cement, flexibility points, etc.) but you don't actually do tests on a completed building.

How does that relate to testing completed cables in their real world environments?

Motorola would analyze the range of envirnments the product is expected to operate in and then apply current good engineering practices regarding shielding.

Those being?

Would a Wrigley's chewing wrapper foil work sufficiently? If not, why not?

rw

[Resident Loser]

...looks like grasping-at-straws time to me...

As MM stated, Belden makes product to fit specific purposes...certain industrial apps are a given...there are formulae, mathematcal models, CAD and the like to aid in design but, it's up to the user(vendor) to determine if that specific design works for them...the real question is: how do these aftermarket companies test for all the items and scenarios you've offered...do they expose their wares to all the possible sources and types of RFI/EMI/EIEIO?

So, if it's not hash from the power source...how many other things can cause problems? proximity to power lines? radio stations? the unique wiring configurations of each home or business? the amount of electronic garbage generated from within?

A simple piece of wire is most susceptible...so maybe a twisted pair is a bit better at keeping the signal coherent and providing a measure of shielding, working it's way up to a CAT5 configuration...keeping in mind, every change in one parameter has an effect on other measurements, in this case capacitance, so designs will make trade-offs...then coax...start with a simple, stranded wrap-aroundwith minimal coverage...then a foil or a tighter weave or perhaps both...then a conductor or two in a foil segregated from other conductors and then all foiled and/or in a weave or both...it's all dependent on use and again remember, in business you buy and pay for what you need...and then there's mil-spec which is usually overkill, based on worst-case scenarios...

And a very desirable performance parameter as it can lower the noise floor

Can it? I thought that to be more of a power supply issue...if the "A" battery provides clean power, I don't know how anything external to it can have an effect, provided that the circuit topography and a well-designed metal case minimize the potential point-of -entry for unwanted interference.

Would you buy a tire that is NOT resistant to hydroplaning?

It can be minimized, there are no guarantees that I'm aware of...too many variables, the a-hole NASCAR/LeMans wannabees being the most egregious...

How does that relate to testing completed cables in their real world environments?

Again, and I sure much like the consumer-level disclaimer, beyond specs, no representation for suitability for each and every application is, or can be, given. It's up to the purchaser to go beyond that level. See my question re: aftermarket providers in paragraph one.

Those being?

I'm sorry, that's a silly question IMO...much like the earlier request for speculation as to Belden's methodology, you are asking someone outside the company to provide info they can't possibly have...asking Motorola would seem to be the logical course of action.

Would a Wrigley's chewing wrapper foil work sufficiently? If not, why not?

Maybe...I've seen some instrument effects pedals that used a simple foil wrap on short jumpers with success...again, too many variables to be any more specific...maybe Reynolds wrap or heavy-duty Reynolds if it's a real turkey.

I think industry has far more possible sources to contend with than our little crumb of the slice-O-pie we're concerned with...they seem so get things done without re-inventing the wheel.

jimHJJ(...is this horse sufficiently dead yet...)

[E-Stat]

As MM stated, Belden makes product to fit specific purposes...certain industrial apps are a given...there are formulae, mathematcal models, CAD and the like to aid in design but, it's up to the user(vendor) to determine if that specific design works for them...the real question is: how do these aftermarket companies test for all the items and scenarios you've offered...do they expose their wares to all the possible sources and types of RFI/EMI/EIEIO?

As with MM, you danced around the question using far more words than necessary. So there is no common test for RF rejection. Interestingly, their 83803 "fire alarm" cable has multiple shielding strategies as opposed to 19364 "portable cordage" which uses only the "Beldfoil" aluminum shield. Both have been used for audio component power cords.

So, if it's not hash from the power source...how many other things can cause problems?

All the devices I previously mentioned.

It can be minimized, there are no guarantees that I'm aware of...too many variables, the a-hole NASCAR/LeMans wannabees being the most egregious...

My point is simply that there are relevant performance considerations for many devices beyond it's basic metrics.

Again, and I sure much like the consumer-level disclaimer, beyond specs, no representation for suitability for each and every application is, or can be, given. It's up to the purchaser to go beyond that level. See my question re: aftermarket providers in paragraph one.

Ditto as above. LCR ain't the whole story for a range of cables used in audio applications.

rw

[Resident Loser]

...sorry you feel that I am, but I earlier gave my best guesstimate at what such testing would entail...I have ab-so-lute-ly no idea as to what Belden's test protocols might be.

So there is no common test for RF rejection

.

I didn't say that...and I don't believe MM did either...there are standard usages, but anyone can use practically anything for any nearly purpose, generally speaking...example: Teflon coated CAT5 wire is designed to transmit data with maximum signal coherence when wired through common air conditioning returns...it's a fire saftey directive in NYC...you can use Plain ol' CAT5 if you are running it in another environment...so if someone takes this more "exotic" PTFE wire and applies it to interconnects, who is then responsible for "testing"?...and what exactly will they be "testing" for? AND how will they do it?

...their 83803 "fire alarm" cable has multiple shielding strategies as opposed to 19364 "portable cordage" which uses only the "Beldfoil" aluminum shield...

Well, the former has a specific application...and again I'd guess something sold for a "life-or-death" app better be up to the task...The wire will be run where other wires will be cohabiting with it...Power, phone, data, CATV, various control circuits...Belden(or any other wire manufacturer) has no control over the environment in which it will be placed or the forms of "hash" it will have to try to guard against...It does have to work with equipment or circuits appropriate for it's function with no adverse loading effects, etc. so there are other considerations to be taken into account.Do they take a worst-case-scenario philosophy? You would have to ask them...

The latter, non-critical applications with a minimum cost, commensurate with general guidelines for a "class" of purpose...I see it as simply logical business practice.

Both have been used for audio component power cords.

Are the wires themselves rated for such use?..Can they handle the voltage and current for such an application? Does the design of the "new" product in any way compromise the integrity or suitability of the original item? Are they UL listed for this use? You can put yer boots in the oven, but that don't make 'em biscuits...

My point is simply that there are relevant performance considerations for many devices beyond it's basic metrics.

Ahhh...the wonderful gray area of audiophilia!!! Who has identified these "considerations"? How have they tested and proven their product's "superiority" in any given respect...Use and listening tests?...Sorry, too many variables, ranging from the myriad number of potential gear combinations, to the type and strength of "interference"... NO ONE can possibly test for every scenario, not Belden and certainly these smaller aftermarket specialists...Are you the R&D?...Great if you feel like doin' it...

jimHJJ(...I personally am not up to the task...particularly in light of the dubious qualities of the net results...)

[E-Stat]

...sorry you feel that I am, but I earlier gave my best guesstimate at what such testing would entail

And I couldn't care less as to how such a measurement is carried out as much as what to measure. You continue to harp on "they can't possibly know all the ways the wire is going to be used" and that is irrelevant for my question. You don't have to know how someone uses a rope in order to measure it's tensile strength. Neither do you have to know how a wire is used in order to measure it's characteristics, either. You have to identify a metric and quantify it. The analysis of the results is then used afterwards for specific application suitability.

Are the wires themselves rated for such use?..Can they handle the voltage and current for such an application?

12/3 and 14/3 is quite sufficient to handle the current needs of most audio amplifiers.

Ahhh...the wonderful gray area of audiophilia!!! Who has identified these "considerations"?

The answer would be every single cable manufacturer who produces shielded audio wires. That would pretty much be all of them.

How have they tested and proven their product's "superiority" in any given respect...Use and listening tests?

Now it's time for me to throw the same irrelevant, "how can I possibly know what Belden and others are thinking in their product offerings" line to you. THERE IS A REASON and it is not based on LCR metrics.

..Sorry, too many variables, ranging from the myriad number of potential gear combinations, to the type and strength of "interference"... NO ONE can possibly test for every scenario, not Belden and certainly these smaller aftermarket specialists...Are you the R&D?...Great if you feel like doin' it...

Forget all that. Bruce (who still hasn't responded) and others continue to harp the simplistic tune that LCR parameters are all that is relevant to the audibility of cables. OBVIOUSLY, that is not the case. Virtually ALL microphone cable, for example, is shielded and LCR metrics don't quantify any aspect of that facet of its design.

rw

[Resident Loser]

...what DO "they" measure? What do any of the aftermarket guys measure? It's all done by ear? Again, given all the variables, what do they listen for?

Shielding is noise rejection as far as I am aware...straight wire with no gain...nothing added, nothing taken away. It seems as though just about every piece of gear has as it's basic premise, the unsullied passage of a signal's waveform...there are expectations as to the "traffic" and conditions it will encounter in it's travel...If the noise floor is limited by the active devices in the path, what do you expect to do, lower it further by use of a passive one, i.e. wire?

Shielded wire by design "shields"...there are special circumstances that require other designs...

Tensile strength? You may be able to take measurement or estimate a number, but there ARE other considerations, so it's not so simple...and it's use is not irrelevant in the overall equation...There's static and active...rope can haul, but it can be used for other purposes...loads are applied to the point of failure...bang! you get a number...climbing ropes are made specifically for that purpose, same type of load testing, sorta'...HOWEVER, climbing rope has a fixed number of times for which it can be used, how many times it can withstand the stretch/shock stress before it MUST be discarded as per the mfr....it is used for NO OTHER purpose during its active life...You surely would not use a hemp rope of similar load bearing properties in lieu of a certified climber's rope; hence some things ARE purpose specific. Other materials have burst strength, torsional loads, etc. all of which are specified and tested for known entities...as is shielding of cable. With wire, it's the ability to reject any change to the signal being carried...

jimHJJ(...unfortunately, gotta' go...tomorrow's another day...)

[FLZapped]

Virtually ALL microphone cable, for example, is shielded and LCR metrics don't quantify any aspect of that facet of its design.

rw

No? then why is there a specification for capacitance to the shield?????

-Bruce

[FLZapped]

Forget all that. Bruce (who still hasn't responded) and others continue to harp the simplistic tune that LCR parameters are all that is relevant to the audibility of cables. OBVIOUSLY, that is not the case. Virtually ALL microphone cable, for example, is shielded and LCR metrics don't quantify any aspect of that facet of its design.

rw

And as usual, you have no idea what you're talking about. -Bruce

[FLZapped]

And I couldn't care less as to how such a measurement is carried out as much as what to measure.

What to measure. Depends on the expected(or recommended) application.

You continue to harp on "they can't possibly know all the ways the wire is going to be used" and that is irrelevant for my question. You don't have to know how someone uses a rope in order to measure it's tensile strength. Neither do you have to know how a wire is used in order to measure it's characteristics, either. You have to identify a metric and quantify it. The analysis of the results is then used afterwards for specific application suitability.

You have it backwards, you need to know the tensile strength of the rope in order to properly use the rope. That's part of your problem, you're perspective is incorrect.

12/3 and 14/3 is quite sufficient to handle the current needs of most audio amplifiers.

If you think that's all there is to it, you're gravely mistaken. You're friends who are using cable designed for limited power applications as power cords as you mentioned, are:

1) Violating the National Electric Code(and maybe several state and local ones) for using a wire with insufficient insulation characteristics.
2) Likely not to be covered by their homeowners insurance in the event of a fire.
3) Putting their safety and the safety of their family at risk for the previously mentioned reasons.

So there are your things that DON'T come down to LCR metrics......

-Bruce