Zip Cord VS Cross Connected Coax Article

[Guest]

<font color='#000000'>What is the most interesting thing for me is that the greatest errors occurred with the most current meter using factory provided cables..the old one, produced the best results....but that's consistent with an equation from 1943 giving the most accurate portrayal of wire inductance..

####,, &nbsp;I hate those error bugs...

I don't know about Gene or Jon, but I have a good excuse...I don't know what it is yet, but it's gonna be really good...if I use some of my work terms, nobody will be the wiser...

As far as accuracy of measuring low impedance transfer function with existing equipment...I have serious concerns..
The b dot error with existing loads is too high for the accuracy we require...Going into the tens of kilohertz, I will question all results, as there's a problem in camelot..

&quot;looks like we're in for nasty weather&quot; (ccr).

Cheers, John</font>

 

[gene]

<font color='#000000'>John;

My excuse is pure carelessness.  I should have known better than to use 1ft of cable in my measurement, and Jon is 100% correct that using 10ft/10 will reduce error.

In my up and coming cable faceoff article, I will be using 8ft lengths for all of my measurements and analysis.

We will also be taking it up a notch and analyzing transient response, group delay, frequency response, etc.


Jon;

One thing I find interesting is in your cable guidelines, you recommend DCR of cable be &lt; .1 ohms.

Jon Risch Cable Guidelines

Yet 50ft of your cable would result in at least .22ohms, over twice your recommendation, while 50ft of 12AWG Zip would only yield .17 ohms, which much closer to what you recommend. &nbsp;Seems to me that 12AWG Zip, according to your guidelines would be better suited for long cable runs than your Cross Coax.


Jon, we may even attempt to measure wire distortion, which I suspect is below the noise floor of even the best test equipment, and certainly audibility.  I seem to remember from your website that your design goal of cable distortion is &lt; -80dB, which is easily measured by an Audio Precision.


Risch Link for Cable Guidelines

Of course, in the past I have taken 8ft 12AWG Monstercable to the Audio Precision Two, and made a distortion measurment that met this requirement with flying colors.

Note: The Audio Precision System Two Cascade Plus delivers an unmatched -112 dB for THD+N in a 20 k bandwidth and worst case harmonics 130 dB down.

But lets not dive into a whole different topic.  We will address this in due time.  

Aren't cables so much fun to debate?

[ added link to JR Cable Guidelines and comments about DCR]</font>

 

[Guest]

<font color='#000000'>Interesting, the way the site eliminates words which may be deemed inappropriate...Human, or machine??

I'm not sure Jon overstated his inductance figure...I seem to be getting close numbers...But, I'm workin on a cable test set to fix the newer HP errors..This work certainly applies to my superconducting magnets (at work)..

Just a little correction..You state &quot;audio, where skin effect is not a factor&quot;..that is where the skin effect factor is the most significant...equation wise that is..

BTW, the pspice analysis.....a thought...

In a complex audio signal, there will be places where bass signals (lf) are added to by highs...what happens when a hf transient affects the overall current in a wire?..Say, a transition from 5 amps 20 Hz, to zero caused by a 20 Khz signal? &nbsp;What happens to the inductance, with the stored energy within the wire?? &nbsp;I personally have no clue...Does it present as a temporal shift of the signal, one which is percieved as soundstage shift?? &nbsp;Does the energy convert to current re-distribution, does it present as a voltage??? &nbsp;Or, it the re-distribution energy neutral?? &nbsp;Unfortunately, Pspice (actually, all e/m field theory math packages available at any price) do not accurately model this issue...Oh well, guess we just have to stab in the dark...

This, and other questions...I do not have answers for...But I look...

In my review of all the e/m theory available (unfortunately, I don't have access beyond the national labs), these questions remain (so far), unanswered...

Cheers, John</font>

 

[gene]

<font color='#000000'>John;

I think you are getting a bit over the top, even for me &nbsp;

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">Does it present as a temporal shift of the signal, one which is percieved as soundstage shift?? &nbsp;</td></tr></table>

Sounds like Star Trek Physics &nbsp;

&nbsp;

As for skin effect, I see it like this. &nbsp;It is skin effect that is responsible for eliminating self inductance at high frequencies. &nbsp;Where as you feel skin effect is the cause of self inductance at low frequencies. &nbsp;Since skin effect is related to frequency, and in turn increases AC resistance at high frequencies, I see skin effect being the cause of self inductance elimination due to added AC resistance of the wire in which the skin effect forces the current distribution to the surface of the conductors. &nbsp;Now who is speaking Star Trek lingo?

I am hoping we can quote Henry on a follow-up to all of this.

Again, I have to you and Jon Risch to thank for forcing me to brush up on E/M basics. &nbsp;I can't believe I actually find this stuff interesting enough to cut into my workouts at the gym &nbsp;

My wife says I am nerding out, perhaps she is right &nbsp;

</font>

 

[gene]

<font color='#000000'>Ok guys, I think I managed to make all of the updates as promised. &nbsp;Please let me know if I left anything out.</font>

 

[Guest]

<font color='#000000'>&quot;&quot;It is skin effect that is responsible for eliminating self inductance at high frequencies.&quot;&quot;

Skin effect is the reason the current profile changes, with the current flowing on the surface being the overall result..

&quot;&quot; Where as you feel skin effect is the cause of self inductance at low frequencies.&quot;&quot;

No..Self inductance is the measure of the energy storage within the conductor as caused by the field lines within the conductor...&quot;Skin effect&quot;, our generic term for the highs going towards the outside of the conductor, is the reason the self inductance goes down..

&quot;&quot;I see skin effect being the cause of self inductance elimination due to added AC resistance of the wire in which the skin effect forces the current distribution to the surface of the conductors. &quot;&quot;

No.. the added resistance is just because less of the cross section of the wire is actually carrying the transport current..The reduction of self inductance is simply the result of less transport current field within the bulk of the wire cross section, a consequence of the current flowing within the cylindrical space of the surface...

&quot;&quot;My wife says I am nerding out, perhaps she is right &quot;&quot;

Your wife is wrong...She incorrectly used the present tense..She should have used the past....

Welcome to the party, pal..

Cheers, John</font>

 

[Audioholics]

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>

Guest : <font color='#000000'>Interesting, the way the site eliminates words which may be deemed inappropriate...Human, or machine??</font>

<font color='#000000'>Machine. &nbsp;

</font>

 

[gene]

<font color='#000000'>John;

I apologize, but when I check my AH email address from an outside server, I cannot retain my address book for some reason.  Please email me again at: gds@audioholics.com.

I have good feedback to share from Henry Ott and he has authorized me to reprint it.

BTW&gt; To quote Henrys book, p149 &quot;The internal inductance is further reduced when high frequency currents are considered since, due to skin effect, the current is concentrated near the surface of the conductor.&quot;

Skin effect doesn't cause self inductance change directly. Self inductance and internal inductance are two different things.  Internal inductance is independent of wire size, thus that kills the notion of skin causing it.

Also, consider 12AWG wire, the skin depth is larger than the cross sectional area for frequencies below 5kHz.  Thus below 5kHz there is absolutely no Skin Effect, yet there is still internal inductance.  Internal inductance eventually gets minimized as a result of skin effect at high frequencies.  Lets discuss further off line and I may turn it into another featured article.

OK John, Here is a Quick Update I worked on.  Tell me if I messed up any of my reasoning:

Calculating Inductance of Twin Feeder Cables

Let me make some definitions applicable to twin feeder cables with two adjacent conductors #1 and #2:


Self Inductance:  is comprised of internal and external inductance (L11 = Le1 + Li1, L22 = Le2 + Li2)

Mutual Inductance: is a result of L1 and L2 interaction (L12) where L12 &lt; Le2, and L2 and L1 interaction (L21) where L21 &lt; Le1.  (Is there a way to calculate coupling coefficient here? IE. In PSPICE I can model two inductors with K-Linear and enter coupling coefficient)

Total Inductance:  Is the sum of Self Inductance and Mutual Inductance where:
Ltot1 = L11 – L12  and Ltot2 = L22 – L21
(The negative sign of the terms L12 and L21, represent current flows in opposite direction of the other conductors L22 and L11, respectively.)

Total Loop Inductance is the sum of Ltot1 and Ltot2 where:

LTOT = Ltot1 + Ltot2 = L11 – L12 + L22 – L21




At Low to Mid Frequencies:
LTOT = .281*Log(B/A) + Li1 + Li2 where B is the space between two conductors and A is the Radius of each conductor.  For very closely spaced conductors, the internal inductance terms may become important.


At High Frequencies:  
Skin effect forces current to surface of conductors, thus internal inductance becomes negligible and Self Inductance becomes equal to External Inductance:

LTOT = Le1 –L12 + Le2 – L21 = .281*Log(B/A)


Summary:

At low to mid frequencies, both internal and external inductance may have to be considered.  As frequency increases, skin effect causes the internal inductance to become negligible, since the current is forced to the surface of the conductors.  The theory behind negligible inductance at high frequencies is, as you previously stated,
<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">&quot;Within a wire carrying DC, there is a uniform current density profile. The magnetic flux within the wire is zero at the geometric center, and increases linearly in value as you move towards the surface of the wire...Outside the wire, the field drops off as 1/R....When a conductor is skinning heavily, as in RF, all the current has
moved to the outside surface of the conductor. From the field equations, the field within an infinitely thin cylindrical sheet of current is zero....So, at infinite frequency, the internal portion of the wire has no field, hence, no energy stored, and no inductance....That is how the skin effect alters the internal&lt;/b&gt; inductance of the wire.&quot;</td></tr></table>




[added more info on inductance, made corrections to thoery and conclusions]</font>

 

[Guest]

<font color='#000000'>In reviewing my previous posts, it seems clear I've been too loose in my terminology....

I have only been talking of the inductance within the conductor, the internal inductance, and the effects skin has on it..When I state skinning reduces self inductance, I am talking of the &quot;internal&quot; portion of that inductance..

Your definition:

&quot;&quot;Self Inductance: &nbsp;is comprised of internal and external inductance (L11 = Le1 + Li1, L22 = Le2 + Li2)&quot;&quot;
and:

&quot;&quot;Skin effect doesn't cause self inductance change directly. Self inductance and internal inductance are two different things.&quot;&quot;

Skin effect reduces the internal inductance, which is one component of self inductance..It therefore causes a reduction in self inductance, but only the internal component..

&quot;&quot;Internal inductance is independent of wire size, thus that kills the notion of skin causing it&quot;&quot;

No, skin does not cause internal inductance.....skin will reduce it by lowering the field integral within the conductor..

And I believe the wire size will determine the rate at which the internal inductance will change with frequency. &nbsp;Perhaps Henry can confirm that..

Now, about that 12 guage...There is a current slew rate dependence on skin depth...When the current slew rate changes, the internal inductance should change instantaneously....When that inductance changes, what is the energy balance??? &nbsp;To equalize that conservation of energy, does the hf transients lead or lag?? &nbsp;Can the leads or lags reach the 5 to 10 microsecond domain, where humans discriminate direction? That is what I talk of with skin effect and soundstage blurring or shifting..

It's not clear to me that the internal inductance changes cannot cause soundfield shifting...so I cannot discount audible effects of skinning..Nor can I confirm, either...Just working on it..

Cheers, John</font>

 

[gene]

<font color='#000000'>John;

It sounds like we are saying the same basic stuff now.  I think I may have been mixing up terms and that is where the confusion began.  I am writing a paper based on this and plan to have Henry and you, if you would like, to peer review it before posting it and becoming prey to the wolves  

While internal inductance is a constant for all conductors within valid bandwidth, I also wonder/suspect if the rate of change as you approach the skin frequency is dependent on wire size.  I will ask Henry.

<table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">Now, about that 12 guage...There is a current slew rate dependence on skin depth...When the current slew rate changes, the internal inductance should change instantaneously....When that inductance changes, what is the energy balance???  To equalize that conservation of energy, does the hf transients lead or lag??  Can the leads or lags reach the 5 to 10 microsecond domain, where humans discriminate direction? That is what I talk of with skin effect and soundstage blurring or shifting..

It's not clear to me that the internal inductance changes cannot cause soundfield shifting...so I cannot discount audible effects of skinning..Nor can I confirm, either...Just working on it..</td></tr></table>

John; you are still losing me here.
The answer is &quot;nothing&quot; because it can't happen. There is never sufficient energy at 20kHz to reduce any signal of reasonable amplitude to zero - the levels are just too small.  I think you are trying to apply terms of the tests and experiments you are working on in your field, rather than the reality of a music signal.

I quote this from a reliable source:
As a rough guide, signal levels fall off at around 3dB to 6dB/octave above about 2kHz, and there are no high amplitude signals above 10kHz - the energy of most transients is a lot lower in frequency.</font>

 

[Guest]

<font color='#000000'>&quot;&quot;The answer is &quot;nothing&quot; because it can't happen. There is never sufficient energy at 20kHz to reduce any signal of reasonable amplitude to zero - the levels are just too small. &nbsp;I think you are trying to apply terms of the tests and experiments you are working on in your field, rather than the reality of a music signal.&quot;&quot;

I am persuing the possibility...I do not know the frequency domain for which the effect would be most apparent, nor, indeed, if the effect truly exists..The bulk of my testing will probably be at vocal freq's, as humans tend to derive directionality in that realm.

But I in general try to shy away from absolute statements..

Seems some bicycle mechanics from Ohio had that attitude back in 1912, and I prefer to emulate that mindset...

Cheers, John</font>

 

[Audioholics]

<font color='#008080'>I dunno, absolute statements are OK, so far as you are sufficiently concerned with only your own, observable universe.

For instance: I am not God. I can say that, knowing it is an absolute statement.

I can also say that humans, so far as they exist today, cannot audibly hear frequencies at 100KHz. That's an absolute statement.

So, while it is good to pursue possibilities, there comes a time when observable and scientific data stares you in the face and draws a conclusion. To ignore these conclusions is to inexorably continue pursuing something that doesn't exist.

Now when do we decide to draw our conclusions... that's the question!</font>

 

[Guest]

<font color='#000000'>Your points are good.  I just said I try to shy from absolute statements....

&quot;&quot;So, while it is good to pursue possibilities, there comes a time when observable and scientific data stares you in the face and draws a conclusion. To ignore these conclusions is to inexorably continue pursuing something that doesn't exist.&quot;&quot;

I agree, to ignore them is not &quot;the best&quot;.

Until such time that the engineering paradigms we have learned and use are scrapped and replaced with new, the best we can hope for is to embrace the current ones..

That is why I've not argued over the &quot;absolute&quot; statements such as skin effect doesn't affect sound, soundstage, audible problems, etc...As the analysis presented to date has been correct w/r to current engineering theories..I'm quite comfortable with the technical content of the articles presented to date and the acceptance of corrections when needed.

For me to argue counter without any proof, any math, anything whatsoever to bring to the table, would be stupid on my part..  For me to present such ideas, it will be necessary for me to change parts of the paradigm.  That is not an easy task, and I've spent about 6 months working towards applicable theory mods, test setup capabilities, etc.  Until I've established real effects do exist, I certainly can't present them as real..  Of course, I can also privide null effect, which is also useful..

&quot;&quot;Now when do we decide to draw our conclusions... that's the question!&quot;&quot;

Which one?  Testing and modelling wire inductance?  We seem to be done with the modelling, perhaps the testing still needs a little work.. I know I've some cabling to build for the meter I use.

For my skin effect hypothesis?  Half a year from now I'll probably be in a better position to answer..

Cheers, John</font>

 

[Guest]

<font color='#000000'>Oh My
All these measurments of cables and not one consideration
about termination ? If you want an accurate measurement
about what a cable is doing in your system you must consider
the termination,simply measuring a cable at both ends is a moot point if you dont take the termination into consideration
If the cable is terminated at the binding posts of a speaker
or amp the measurement is sure to change directly after
that connection.... Just thinking outloud.... &nbsp;

</font>

 

[gene]

<font color='#000000'><table border="0" align="center" width="95%" cellpadding="0" cellspacing="0"><tr><td>Quote </td></tr><tr><td id="QUOTE">All these measurments of cables and not one consideration
about termination ? If you want an accurate measurement
about what a cable is doing in your system you must consider
the termination</td></tr></table>

Ray;

Note sure I really follow you here. &nbsp;The purpose of the article was to compare two different cables. &nbsp;Lets assume they are both terminated identically, the termination becomes irrelevant. &nbsp;Also, terminations differences may result in contact resistance changes, but they will rarely have an effect on inductance or capacitance.</font>

 

[Guest]

<font color='#000000'>My intent was not to take anything away from the artical
It was well written and to the point Resitance is Resistance
it does not matter where the resistance occurs it is
a major factor in the linkage between a amplifires output and the transducer it is powering.Many manufactures of
Mid and Hi End equipment overlook this important part of there product and resistance changes will occur from product to product There is no way a cable can for see this problem
I guess what I am trying to say is that it is not a good idea
for one to try to &quot;tune&quot; there systems using cables
there are just to many variables involved Spend your cash where it will do some good and tune your room your room instead
Ray</font>

 

[gene]

<font color='#000000'>Ray;

That is very sensible advice and I agree. &nbsp;If you get a chance, review our cable articles where we discuss important metrics of cable design.

Here is one link to our Budget Guidelines for Cables
Cable Budget Guidelines

The bottom line is that there is really not that much to cables. &nbsp;Sadly however, we have to expend quite a large effort to prove that since there has been so much unchallenged misinformation spread by many cable vendors and cable cult hobbyists for so long.

Room treatment, quality of the recording, loudspeaker design, placement, etc all have a far more profound impact on improving a systems sound as opposed to wire tweaks.</font>