Cable and EMC discussion (Split from "What if the Audio Critic was completely right")

[jnjn]

Quote:

 
I used it as an example, not a strawman (that's the wrong use of the term BTW).
 
It stated that those three things are the only things which can impact performance. You haven't shown that anything else impacts performance. I'm defining performance as audible neutrality. This can't be more clear. Please respond with evidence that anything else affects the signal in an audible fashion.

Oops, it kinda was a mix between the two IMO..
 
I provided evidence.  Go back and read it..post #80 (at this time).  ps..as I suspected, that "post" was removed, my "evidence" post is now #78.   Thank you mods, much appreciated.
 
Cheers, jn
 
 

 

[kevin gilmore]

Quote:

 
Coaxial cables have a measurable, defined impedance. Twisted pair has a measurable, defined impedance. Regular twin cable (speaker) does not have a measurable, defined characteristic impedance.
 
 

If you are talking about lamp cord, the cable definitely does have a characteristic impedance and it is pretty uniform over length, something many of the twisted cables and other whacky
geometrys seem incapable of.  16 gauge zip cord is about 95 ohms.  The lowest impedance cable is goertz, and is something like 4 ohms because it has a very high capacitance.
You could even use RG8 which has an impedance of 50 ohms, and is equivalent to about 17 gauge.
 

 

[Head Injury]

Quote:

Oops, it kinda was a mix between the two IMO..
 
I provided evidence.  Go back and read it..post #80 (at this time).
 
Cheers, jn

I'm talking more along the lines of things like extended bass and larger sound stage. The stuff normally attributed to cables. That's the sort of thing the article is talking about, too.

 

[wakibaki]

Quote:

If you are talking about lamp cord, the cable definitely does have a characteristic impedance and it is pretty uniform over length, something many of the twisted cables and other whacky
geometrys seem incapable of.  16 gauge zip cord is about 95 ohms.  The lowest impedance cable is goertz, and is something like 4 ohms because it has a very high capacitance.
You could even use RG8 which has an impedance of 50 ohms, and is equivalent to about 17 gauge.
 

 

The reason it doesn't have a defined impedance is that it doesn't have a stable, defined geometry. If you twist it (easily done) the impedance changes, unlike ladder line (which mustn't be twisted), coaxial or twisted pair (which has a specific TPI). I don't know where you get the 'whacky geometries' idea from but the assertion that that they 'seem incapable of' maintaining an impedance which is uniform over length is inaccurate. The impedance is maintained as long as the cable geometry is not abused, i.e. it is used as specified.
 
Quote:

4.  ABX is flawed whenever a switchbox is used.  Changes in the system caused by even putting the box in renders comparisons meaningless.  This is from EMC concerns.

 
Quote:

There are systems out there which are not susceptible to EMC problems, but so far I find that many times it is by accident rather than design.  But it is certainly important to preserve the differences one wishes to test for, so sometimes just swapping or switching doesn't preserve the differences being tested for.  

So which is it? Is it 'whenever a switchbox is used' or just sometimes, as in 'sometimes just swapping or switching doesn't preserve the differences being tested for'?
 
 
EMI is a problem only when suitable measures to prevent it are not taken. I have taken numerous items through CISPR tests. Some failed at first, but it has always been possible to engineer a solution.
 
Your introduction of EMC to invalidate comparison testing is a red herring. EMI can be engineered down to whatever level is required.
 
If necessary testing could be carried out inside a Faraday cage.
 
Please tell me how the inclusion of a switch for comparison purposes automatically invalidates ABX testing for reasons other than problems with EMI.
 
Why would 'swapping or switching' not preserve the differences being tested for?
 
What is it about 'even putting the box in' that 'renders comparisons meaningless'? It sounds close to superstition to me. Please explain the scientific basis for this assertion.
 
Cheers, w
 

 

[Prog Rock Man]

I still think resistance can affect SQ by having slight affects on volume due to attenuation.

 

[jnjn]

 
Quote:

If you are talking about lamp cord, the cable definitely does have a characteristic impedance and it is pretty uniform over length, something many of the twisted cables and other whacky
geometrys seem incapable of.  16 gauge zip cord is about 95 ohms.  The lowest impedance cable is goertz, and is something like 4 ohms because it has a very high capacitance.
You could even use RG8 which has an impedance of 50 ohms, and is equivalent to about 17 gauge.
 

Spot on.
 
Quote:

I'm talking more along the lines of things like extended bass and larger sound stage. The stuff normally attributed to cables. That's the sort of thing the article is talking about, too.

It would be best to consider the numbered items one at a time.  At present, discussion is on item 1, and the erroneous statement that only R, L, and C are the only things that matter at frequencies below rf..
 
 
When I found that my system was heavily dependent on the cable selections for IC's and power cord, it reacted in entirely unexpected ways, modifying the sound no end.  Since I used it for mobile apps, I ran the livin bejeesus outta it and found that from setup to setup it never exactly sounded the same, something was "wrong" although I could not put a handle on it.  Sometimes there'd be what appeared to be hum riding on high power passages but not during quiet passages (line cord power draw coupling to the input circuits), noise modulated by the bass lines, sometimes more noise, sometimes less, sometimes the vocals distorted...and of course, the infamous tweeter capacitors explosion.  When I set the exact same system in my room between gigs, I could not repeat all the results.edit:  all the problems I could hear were during mobile use in constantly changing environments, so I was in no position to even consider soundstage, and the bass always depended on the size of the venue and half space/quarter space, or eighth space setup of the speakers...I liked eighth space best, really kicked the pantlegs..
 
Once I re-designed the grounding topology within the power amp and the source components, every single effect I ever had problems with went away. (well, not fan noise nor the weight of 4 K horns built from particleboard).
 
The word "topology" is the key item here.  The circuits themselves were great, both in the source and in the amp.  The problem stemmed from the physical design which did not consider the effects of both ground currents caused by the interconnection of chassis' by way of cables, nor the internal couplings between high current supply rails and output wires to any sensitive circuitry.
 
I can certainly see how poorly designed topologies could effect the entire audio spectrum, but it's the equipment at fault here, not the cables.  Equipment designed with EMC in mind will not have cable sensitivity, and once that is done, RLC will indeed be the only things that matter...

What boggles my mind is...what kind of business model is it where you proclaim "truths" which in hindsight are generally not; to an audience that may find some of those truths to be inaccurate..an audience not particularly interested in 100 dollar receivers but higher end stuff..  One "gotcha" trashes credibility, and you immediately lose a customer.
 
A more even tempered and concise article would have been better IMO.  edit:  What he actually did was painted himself into a corner in a market where credibility is a requirement for sales.
 
cheers, jn
 

 

[jnjn]

 
Quote:

Cheers, w
 

I apologize in advance for copying your statements and posting them outside the quote box.  I have changed your text to red to keep track.  I've not mastered this forum's editing features..

 
The reason it doesn't have a defined impedance is that it doesn't have a stable, defined geometry. If you twist it (easily done) the impedance changes, unlike ladder line (which mustn't be twisted), coaxial or twisted pair (which has a specific TPI). I don't know where you get the 'whacky geometries' idea from but the assertion that that they 'seem incapable of' maintaining an impedance which is uniform over length is inaccurate. The impedance is maintained as long as the cable geometry is not abused, i.e. it is used as specified.
 
What he was speaking of was the lack of geometric control of the wires.  Many times people will twist the wires using a drill or the like, and when you release the cable, it will untwist.  When it does this, the spacing between the conductors will open up, and you've lost control of the parameters of the cable.  To twist two or more wires together and maintain the characteristic impedance, you have to not twist the individual conductors as the drill does.  I made such a contraption to twist up a quad #12awg speaker cable run, it had 4 spools of wire each on it's own lazy susan, and the overall spool assembly was on a larger lazy susan. (I could post a pic of it, but it seems I've made a mess of my default picture album).  What I really need is a ten year old kid to show me how to work this forum)...  As for "wacky geometries, some of the vendors out there do indeed have wacky geometries, and some do not control the geometry sufficiently to maintain any impedance along the length.
 
ps..twisting cables does not change the cable's impedance in general. Only if the twist brings the conductors into intimate contact where they previously were not will the impedance change.

So which is it? Is it 'whenever a switchbox is used' or just sometimes, as in 'sometimes just swapping or switching doesn't preserve the differences being tested for'?
The introduction of any additional entity to make switching easier always requires consideration of the change.  If you are trying to test a cable which has an extremely low inductance per foot against one with a normal inductance per foot, it is very important to consider the inductance of any additional switching mechanism.  If you are testing power cords, the grounding resistance and the hot/neutral coupling to external grounding loops is important.
 
EMI is a problem only when suitable measures to prevent it are not taken. I have taken numerous items through CISPR tests. Some failed at first, but it has always been possible to engineer a solution.
You are attempting to shoehorn RF testing where it is not being discussed.  As someone once said to me, you have a hammer so consider everything to be a thumb..
RF susceptibility and radiation are indeed important, but that's not what's being discussed.  EMC is wider in scope.  As I said, I can either answer your questions, or point you to content.
 
Your introduction of EMC to invalidate comparison testing is a red herring. EMI can be engineered down to whatever level is required.
As I stated, it is important for you to learn the distinction between full EMC and RF.
 
If necessary testing could be carried out inside a Faraday cage.
This also assumes only RF, not EMC.  It is not about far field incursion of planar waves, it is about nearfield coupling.
 
Please tell me how the inclusion of a switch for comparison purposes automatically invalidates ABX testing for reasons other than problems with EMI.
I already have, so do not understand why you repeat this question.
 
Why would 'swapping or switching' not preserve the differences being tested for?
Already answered.
 
What is it about 'even putting the box in' that 'renders comparisons meaningless'? It sounds close to superstition to me. Please explain the scientific basis for this assertion.
Already have.  edit:I've removed my statement formerly here referencing the post of yours that was deleted, this is only fair..
 
 
I will admit that much of this has not been taught in venues of higher education, so I cannot blame you nor others for not understanding it.  Continued refusal to learn it, that is a different story.  Heck, the knowledge doesn't even have to come from me, as that is an obvious problem for you.
 
As I've stated, I can answer your questions, or I can refer you to links.  Once understood, it's not rocket science.
 
Cheers, jn

 

[kevin gilmore]

So i just took a 20 foot piece of 16 gauge white zip cord.  Measured it with my TDR at 94 ohms.
Then put 20 turns (i.e. 1 turn per foot) and measured again.  94 ohms.
Then 40 turns still 94 ohms.
To get the cable to 93 ohms i had to put 6 turns per foot.
 
Unless you are going to do evil things to this stuff it has to be considered to be constant impedance.
 
Now i took one of the multi-geometry cables, and measured it absolutely straight at 66 ohms.
Then just one 90 degree gentle bend, and at the bend, 59 ohms. All the tubes of air inside the
cable work great till you have to actually hook them to something.

 

[jnjn]

Quote:

So i just took a 20 foot piece of 16 gauge white zip cord.  Measured it with my TDR at 94 ohms.
Then put 20 turns (i.e. 1 turn per foot) and measured again.  94 ohms.
Then 40 turns still 94 ohms.
To get the cable to 93 ohms i had to put 6 turns per foot.
 
Unless you are going to do evil things to this stuff it has to be considered to be constant impedance.
 
Now i took one of the multi-geometry cables, and measured it absolutely straight at 66 ohms.
Then just one 90 degree gentle bend, and at the bend, 59 ohms. All the tubes of air inside the
cable work great till you have to actually hook them to something.

Very nice.
 
I suspect that at 6 turns per foot, you are starting to compress the insulation between the conductors, so the inductance dropped a tad and the capacitance rose.
 
Cheers, jn
 
 
 

 

[Head Injury]

Quote:

a market where credibility is a requirement for sales.

You're kidding, right?
 
My point is, beyond special cases where a certain cable causes obvious problems in the system (which could be what you're talking about, or it could be things like lack of shielding against a nearby source of interference, dropped signals in digital cables over long runs, etc.) there is nothing special about cables besides RLC. That's one of the requirements objectivists have set to determine differences between cables. As long as there's not something seriously wrong (because it's easy to screw things up!) then cables won't sound different. The cables to be compared have to be competent for the task, but beyond that basic level they're all okay. So I guess we sort of agree now?

 

[jnjn]

Quote:

You're kidding, right?
 
My point is, beyond special cases where a certain cable causes obvious problems in the system (which could be what you're talking about, or it could be things like lack of shielding against a nearby source of interference, dropped signals in digital cables over long runs, etc.) there is nothing special about cables besides RLC. That's one of the requirements objectivists have set to determine differences between cables. As long as there's not something seriously wrong (because it's easy to screw things up!) then cables won't sound different. The cables to be compared have to be competent for the task, but beyond that basic level they're all okay. So I guess we sort of agree now?

No, I'm not kidding.  One of problems I see with this "net" thing, is all said goes to the entire planet, and stays there forever.  If your gonna make your name spouting absolutes, it is important that the absolutes be absolutely accurate.  I read that TAC is no longer, is that correct?
 
I have already known all along that we agree.  The disconnect has been this:  EMC considerations for audio equipment is almost entirely non existant.  As a consequence, darn near all systems are susceptible to changes in both IC's and PC's.
 
To make the absolute statement that "the selection of an IC or PC CANNOT alter how a system sounds and I know this because physics says so" is  sheer folly..entirely inaccurate.  Physics does not say that, and anybody who makes that claim is doomed to failure eventually.
 
Now, his initial statement that "EXPENSIVE cables make all the difference" (as an audio lie), that is certainly not inaccurate, but definitely incomplete.  There is in general, no understanding of how a cable can affect a compromised system, so therefore there is no correlation between price and performance...the caveat to that can be that the cable design alters loop coupling by sheer size of the grounding conductors, or geometric changes of significance.  For example, a #12awg IC shield, while overkill normally, reduces the IR drop error caused  by a ground loop so the amp reference is cleaner...But this also increases the loop currents that go into the chassis, and IR drops consistent with pin 1 issues will increase, as well as inductively coupled higher frequency components of the loop current.
 
In general, cord selection is entirely random.  No actual science was used to create the cord that will impact it's contribution to an EMC challenged system.
 
Cheers, jn

 
 

 

[Head Injury]

Quote:

No, I'm not kidding.  One of problems I see with this "net" thing, is all said goes to the entire planet, and stays there forever.  If your gonna make your name spouting absolutes, it is important that the absolutes be absolutely accurate.  I read that TAC is no longer, is that correct?

By that same reasoning, the majority of independent audio manufacturers and audio reviewers would be out of a job. 6moons is still in business.
 
Correlation != causation. Doesn't matter if TAC is out of business, doesn't mean it has a thing to do with the facts they used and whether or not they were correct. As a lover of science, you should know that.

 

[jnjn]

Quote:

By that same reasoning, the majority of independent audio manufacturers and audio reviewers would be out of a job. 6moons is still in business.
 
Correlation != causation. Doesn't matter if TAC is out of business, doesn't mean it has a thing to do with the facts they used and whether or not they were correct. As a lover of science, you should know that.

It was not my intent to imply causation.  It was just a question, as I'm not sure if they are or not.  Don't try to read so much into it.
 
I do however, still stand by my assertion that it is not good business to hinge one's reputation on absolutes in that fashion, because if the absolute is not accurate, credibility is lost.  If one's chosen market relies on a reputation in that manner, customers will leave when the rep is lost.
 
Cheers, jn
 

 
 

 

[wakibaki]

 
OK, firstly, with regard to cable geometries and impedance, you prove my point precisely.
 
You twisted the lamp cable, the impedance changed. 6 turns per foot is trivial to achieve by accident, twisted pair is specified with turns per inch.
 
You exceeded the bend radius of the co-ax, the impedance changed.
 
No surprises there then.
 
jnjn, do you stand by this statement? 'even putting the box in renders comparisons meaningless'
 
Cheers, w
 
 

 

[wakibaki]

Quote:

it is not good business to hinge one's reputation on absolutes in that fashion, because if the absolute is not accurate, credibility is lost.
 

Hmmm.
 
Cheers, w