 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
199.60.112.10
In Reply to: Umm, you.. posted by jneutron on April 3, 2006 at 13:44:29:
hiNObody is infallible. But if one finds someone's statement not clear, incorrect, or whatever it may be deemed, just point out which part of the statement is questionable & debatble.
Making a sweeping criticism without pin-pointing the issue will not help. Besides, how is one so sure the questions are even justiable basing on self assumed 'facts' or simply on one's speculation or assumption. Make sure one can substanatiate its criticism or remarks against anything allegedly incorrect.
BTW, this wire & cable fundamental is taken out from a paper published by a leading cable manufacaturer in the USA. I take nothing for granted.
c-J
Follow Ups:
CJ: ""Making a sweeping criticism without pin-pointing the issue will not help. Besides, how is one so sure the questions are even justiable basing on self assumed 'facts' or simply on one's speculation or assumption. Make sure one can substanatiate its criticism or remarks against anything allegedly incorrect.""
You discussed the prop velocity and how we can hear the differences but yet do not have the ability to measure it.You were therefore asked, how?
It is a simple and logical question which arises from your statement. So, logically, it is a justifiable question.
CJ: ""BTW, this wire & cable fundamental is taken out from a paper published by a leading cable manufacaturer in the USA. I take nothing for granted.""
Unfortunately, what you have done is taken out of context , what appears to be correct information, and incorrectly applied it to the topic at hand.I explain..
The information you provided is the determination of velocity of propagation for a fully formed e/m wave (TE, TM, and TEM), unconstrained by any physical barriers.
The equation of course, being υ = c/√ (ε μ)
You have cut and pasted information from a site which only considers the variation of ε without regard to μ. So they are only considering the propagation through an isotropic medium with μ equal to that of free space.
That is not how most wires (transmission lines) work.
The ONLY transmission line which has the ability to transfer a signal at the free space velocity of the dielectric is a coaxial line. The coaxial line constrains the magnetic field via external cancellation, and confines the E field within the dieleictric. For all other cases, the velocity of propagation is reduced by the lack of control of the external fields. Zip cables, for example, create a dipole field externally, so does not use the dielectric solely, but uses also the external space around the pair, that being free space.
Note that this use of external space with it's DC of 1, does not mean that the prop velocity will increase. In point of fact, it causes the velocity to decrease.
The equation for any cable is:
υ = c/√ (LC)
Further bounds:
LC = 1034 * ε r (for coax)
L in nH per foot, C in pf per foot
LC = 1034 * ε effective for all other cases,
ε effective being the geometrically determined effective ε r ..I am keeping this simple by ignoring the effective μ, which is really how the unconstrained magnetic field system operates..
If your source thinks otherwise, I will be happy to correct them..
Cheers, John
Hi.First off, what I did was an attempt of some qualitative analysis which may lead to why we hear the difference in cables due to their
construction.I did already state clearly we don't even know what to measure let alone the effective instrumentation available to make such measurement valid to what we hear. Yet you still reiterate the forever tune of the naysayers: "YOU do not have the ability to measure it". So do YOU have the ability to measure it then????
Give me a break, please. I'm sick & tired to read this sterile commente all the time.Surely the signal propagation velocity is based on the ideal situation of vacuum or "free space", which would never happen in the realworld, regardless whatever construction of the transmission line, namely coaxial cable. So, your statement is WRONG.
For any straight ROUND copper conductors, the v.c. factor is the reciprocal of the square root of the effective dielectric constant (e) of the conductor insulation. Wherever there is insulation dielctric, there is a delay. This is nature. So how come your statement: "the ONLY transmission line which has the ability to transfer a siganl at the FREE SPACE velocity of the dielectric is a coaxial line"? You assume a coaxial cable is a bare wire w/o insulation?
The velocity of a wave in a coaxial cable can be expressed as a percentage of the velocity of light. For a coaxial cable using solid PE, it v.c. is 0.659, & e=2.26
However, using foam PE where air is trapped inside the foamed dielectric, say RG-62 coaxial, the effective e is much less & v.c. is higher due to the air trapped inside, i.e. v.c.=0.80 & e=1.55.
I used v.c. & e to explain the delay of signal transmission which will surely give some perspectives easier for our readers to understand.
Now you bring in something else: "magnetic field" & "E field".
YOU are now complicating the issue which I tried to explain in simple language.So what "magnetic field" & "E field" are to do with what we hear? Please explain it in simple language so that our readers can understand.
The bunch of forumulae won't help anyway. You put them there to scare
off people?So let me go back to H & E field you bring forth which you failed to explain why you mentioned them relative to cable sonics.
The relative amplitudes of electric field (E) & mangetic field (H)
due to a signal passing through a transmission line, say, a coaxial cable is determined by the capacitance & inductance per unit length of the cable (assuming NO, repeat no reflections from the load).The characteristic impedance (Z) = E/H = square root of L/C.
Another simple equation for Z is Z= 101,600/capacitance x v.e. of the insulation dielectric.
From the 2nd formula, we can see the faster is the v.e of the insulation dieelctric, lower the the impedance.
You could be a great scholar, but you got make our readers understand what you want to tell.
c-J
PS: the info. given my my posts are referenced from:
Radio Engineers Handbook, Pulse, Digital, & Switching Waveforms,
& Reference Data for Radio Engineers.
CJ: ""First off, what I did was an attempt of some qualitative analysis which may lead to why we hear the difference in cables due to their construction.""No. Actually, what you did was cut and paste some info, that is all. You still did say you hear the diff, but have not yet answered that question.
CJ: ""I did already state clearly we don't even know what to measure let alone the effective instrumentation available to make such measurement valid to what we hear. Yet you still reiterate the forever tune of the naysayers: "YOU do not have the ability to measure it". So do YOU have the ability to measure it then????""
What is this naysayer crap you hide behind. Stick to the subject at hand.You may be unable to understand what or how to measure, that is your limitation, not mine.
cj: ""Give me a break, please. I'm sick & tired to read this sterile commente all the time.""
I provided a correct analysis breakdown. You are bringing in this naysayer bullshit..please refrain from diversions, but instead, attempt to be correct in your posts regarding e/m theory.CJ: ""Surely the signal propagation velocity is based on the ideal situation of vacuum or "free space", which would never happen in the realworld, regardless whatever construction of the transmission line, namely coaxial cable. So, your statement is WRONG.""
Surely?? You must attempt to find a text from which you can get the correct information. I used Jackson, Becker, Rojansky, and Shodowitz. (separate books and authors, If you wish the titles, chapters, pages, I can provide them.The signal property in free space is exactly the equation I provided, and it is invariant on the form of e/m wave that is propogating. The velocity within a wire pair is also exactly as per the equation I detailed. That is invariant as well..
Didn't you learn this stuff in school?? Again, I could provide factual information in this regard.
Oh, btw..I really didn't understand the point you were trying to make in that last sentence..
CJ: ""For any straight ROUND copper conductors, the v.c. factor is the reciprocal of the square root of the effective dielectric constant (e) of the conductor insulation. Wherever there is insulation dielctric, there is a delay. This is nature. So how come your statement: "the ONLY transmission line which has the ability to transfer a siganl at the FREE SPACE velocity of the dielectric is a coaxial line"? You assume a coaxial cable is a bare wire w/o insulation?""
No. My statement says that if a coax is made with vacuum as the dielectric, the prop velocity of that coax will be the speed of light. My statement also says that if the dielectric is not vacuum, but instead a dielectric of value greater than 1, the prop velocity in that coax will be the same as the propagation of an e/m wave passing through that dielectric. For example, if you try to send a radio wave through a large volume of teflon, it will pass through it at the prop velocity consistent with teflon's dielectric constant. And that velocity will be identical to the velocity of a coax constructed of the same material.
Your statement is correct for coaxial constructions, that of reciprocal square root. Note that this is exactly what I said, with the equation v = c / sqr(epsilon mu), you are describing only a system with mu = 1, which is a constrained example.
CJ: ""The velocity of a wave in a coaxial cable can be expressed as a percentage of the velocity of light. For a coaxial cable using solid PE, it v.c. is 0.659, & e=2.26 ""
Of course. Why was it necessary to explain that? If you look at the equation I posted, you can clearly see the "c" in the numerator, with both epsilon and mu in the denominator, in that square root thing..
CJ: ""However, using foam PE where air is trapped inside the foamed dielectric, say RG-62 coaxial, the effective e is much less & v.c. is higher due to the air trapped inside, i.e. v.c.=0.80 & e=1.55.""
You explain that correctly, and again, this is consistent with the equation I posted.
CJ: ""I used v.c. & e to explain the delay of signal transmission which will surely give some perspectives easier for our readers to understand.""
This is a technical forum. Most already know this..
CJ: ""Now you bring in something else: "magnetic field" & "E field".YOU are now complicating the issue which I tried to explain in simple language.""
Your attempt to explain in simple language used material which had relevence only to propagation in free space, or within a coaxial construction. The simplistic explanation you gave, therefore, missed the majority of the boat, so to speak. In point of fact, the vast bulk of energy storage and propagation velocity modification is indeed as a result of the inductance of the system. Only for transmission line constructs which have a characteristic impedance close to that of the load, will the energy within the cable be minima, and of least impact on the end result.
If you cannot understand my explanation, just ask. It is not a sin, nor a sign of stupidity to ask questions. If it were an easy topic, it would be waaaay too boring.
CJ: ""So what "magnetic field" & "E field" are to do with what we hear? Please explain it in simple language so that our readers can understand.
The bunch of forumulae won't help anyway. You put them there to scare
off people?""No. I put them there to explain to YOU that what you posted was only the simple relation for prop velocity in free space. You missed entirely, half of the physics. That being the magnetic field and the inductance.
Those equations WERE the simple explanation.
CJ: ""So let me go back to H & E field you bring forth which you failed to explain why you mentioned them relative to cable sonics.""
I mentioned them because of the inaccurate way in which you attributed free field propagation to constrained propagation.CJ: ""The relative amplitudes of electric field (E) & mangetic field (H)
due to a signal passing through a transmission line, say, a coaxial cable is determined by the capacitance & inductance per unit length of the cable (assuming NO, repeat no reflections from the load).""
Yes. correct.CJ: ""The characteristic impedance (Z) = E/H = square root of L/C.""
Again, correct. And, the characteristic impedance is the impedance where the amount of energy stored within the inductance is equal to the amount of energy stored within the capacitance. This relationship can be easily derived, and is the exact reason that the advancing wavefront will not reflect when it hits a matched load, as the load satisfies the parameters that have setup within the transmission line.CJ: ""Another simple equation for Z is Z= 101,600/capacitance x v.e. of the insulation dielectric.""
Simple, yes..accurate..no. What is missing is the energy storage as a result of mu, which is the inductive relation. This simple equation was derived for a specific need, that of coaxial cables. It cannot be considered for use in any other cable construction, as that is an incorrect use of the equation.CJ: ""From the 2nd formula, we can see the faster is the v.e of the insulation dieelctric, lower the the impedance.""
It is correct only for a coaxial system. It is useless for any other.
CJ: " ""You could be a great scholar, but you got make our readers understand what you want to tell.""
It is irrelevant whether or not I am a scholar. What is relevant is the use of the correct equations for the correct situation. You have pulled some very useful equations, and used them incorrectly.
CJ: ""PS: the info. given my my posts are referenced from:
Radio Engineers Handbook, Pulse, Digital, & Switching Waveforms,
& Reference Data for Radio Engineers.""That certainly explains why you used them incorrectly.
If you go back to that text, hopefully, you will find the constraints that should have been explained to the reader, so that they understand which situations are not covered by the formula you used. If you do not find that, perhaps you should e-mail the authors and explain to them the fact that they neglected to specify the boundary conditions and system constraints which apply to the use of those formulas. E-mail them these posts if you wish, so that they understand. Then, tell us what they said.
They are good formula, but they are not general ones which apply to non coaxial constructions, which the bulk of speaker wires are not.
Oh, almost forgot..relevance to what we hear..
Both capacitance and inductance within a speaker run are energy storage mechanisms. And, both are lagging.. Consider the response to a sine wave into a load in the first quadrant of operation. As the voltage rises (charging the capacitance of the cable) the current also rises (charging the inductive component). At the peak voltage and current, the energy storage within both components are at a maximum. Only when the cable z matches the load will this storage be at a minima.
This energy storage is not insignificant with respect to the levels of the energy that are being delivered to the load..they are in the 2 to 10% regime, depending on the z/load mismatch. They are orthogonal to the signal we are trying to listen to (90 degrees lagging for sine wave only) They cause group delay within the capability of human hearing..
This storage is easily calculated. Measurement of the group delay at typical speaker load impedances is way beyond the majority of engineers out there. They cannot design a load or cvr capable of the low inductance required for accuracy.
Cheers, John
Hi.First off, I already stated we cannot measure relevantly what we hear.
YOU still pursue this measurement issue. Yet you still fail to answer my counter question: "do YOU have the ability to measure it" -anything relevant to what we hear given your statement to me: "you may be unable to understand what or how to measure, that is your limitation, not mine".
Where is your answer as you already said you know how ??????
Failed to answer this your own issue, you diverted to something else not touched in my post instead - magnetic & electric fields.
What correct breakdown of what? I reiterate this is only an attempt of QUALITATIVE analysis based on wave progation velocity &
insulation dieelctric. You jumped in with your so called "half of the physics" - magnetic & electric fields.Yet you failed to correlate how E & H affect or NOT affect the sonics of wires & cables. A totally moot diversion from the sonic issue.
Back to your moot argument on coaxial cable issue.
"The ONLY transmission line which has the ability to transfer a signal at the FREE SPACE velocity of the dielectric is a coaxial line"What is a "free space velocity of the dielectric"? Where can I find your back-up explanation "that if a coax is made with vacuum as the dielectric" in your above statement ????????
How can you expect anybody to understand what you meant w/o your
back-up explanation?First off, a coax always comes with a dielectric. Your "IF a coax is made with vacuum" does not exist & your reasoning is moot.
I already stated clearly an ideal wire is a bare wire & there will be very little propagation delay in free air. In vacuum, the wave will travel in light speed along that wire. The idea is exactly the same as you justed posted.
However, your statement: "if a COAX is made with vacuum as the dielectric, the prop velocity of that coax will be the speed of light" is very questionable.
What is a coax? It comes with an overal surrounding shield ideally equi-distant to the centre conductor from all side. This is a capactor by itself due to its construction, regardless the dielectric is a realworld material or a theoretical vacuum as you suggested.
Its capacitance is given by the formula: c=7.36x(e) divided by Log10 D/d where e is the dielectric constant & D is the outside diameter of the coaxial cable (includes the shield) & d is the diameter of the centre conductor. Unit is pF/ft
With capactance involved, how can you expect light speed transfer of a signal along a coax even with theoretically vacuum as dielectric?
Then you diverted even out of wack on speaker cable vs speaker energy storage. What's that to do with ICs the original poster inquired?Let me quote a statement from the published paper:
"The shape, diameter & spacing of the conductors and shields determine the capacity between them. Coaxial cables are a special application version of a single shielded conductor and may be treated in the SAME way."I would not lightly dispute what is written in your textbooks. I only question how you apply it to the cable sonics we are talking about.
A bunch of formulae would not necesssarily help in situation like this where the original poster was seeking for simple answers.
c-J
CJ: ""First off, I already stated we cannot measure relevantly what we hear.""And my response was, and still is..it is trivial to measure changes that result from different wires. It requires measurement technology which is beyond the simplistic information that you are presenting. Note that I am speaking of the information as being simplistic, not you. The information you have read has been simplified for specific applications, they remove the burdon of e/m theory from the reader. I admire you for your attempt at using the information, most would not put that much effort into it. thank you.
CJ: ""YOU still pursue this measurement issue. Yet you still fail to answer my counter question: "do YOU have the ability to measure it" -anything relevant to what we hear given your statement to me: "you may be unable to understand what or how to measure, that is your limitation, not mine". Where is your answer as you already said you know how ??????""
I answered that, re-read the prior post. I also point out the lack of research into what the measured changes really mean to humans w/r to localization.
CJ: ""Failed to answer this your own issue, you diverted to something else not touched in my post instead - magnetic & electric fields.""
You must slow down..Please read the posts slowly and carefully.
CJ: ""What correct breakdown of what? I reiterate this is only an attempt of QUALITATIVE analysis based on wave progation velocity &
insulation dieelctric. You jumped in with your so called "half of the physics" - magnetic & electric fields. ""Use of half of the physics involved in signal propagation cannot be confused with a "Qualitative analysis". It is in NO WAY a qualitative analysis.
Propagation of a signal along any wire requires understanding of both the electric field, and the magnetic one. They are inseperable(sp?)
Your statement about a wire passing signal ignores the fact that a wire has inductance, therefore a reactance.CJ: ""Yet you failed to correlate how E & H affect or NOT affect the sonics of wires & cables. A totally moot diversion from the sonic issue.""
Re-read the posts..CJ: ""With capactance involved, how can you expect light speed transfer of a signal along a coax even with theoretically vacuum as dielectric?""
Go through the equations, you will understand.
The permittivity of a vacuum is not 1, nor is it zero. There is a specific number associated with it, that being 8.854 12 -12 F/m. The equation for capacitance requires that term and the relative permittivity..for example, a flat plate capacitor equation is:
C = (ε r ε o Area )/distanceIf you use a vacuum, ε r is equal to 1. If you use nitrogen gas at 68 F, ε r is equal to 1.000580. I leave it to you if you wish, to calculate the difference in prop velocity for a coaxial cable constructed of either dielectric.
CJ: ""Then you diverted even out of wack on speaker cable vs speaker energy storage. What's that to do with ICs the original poster inquired?""
All cables coax or otherwise, will store reactive energy when transferring signal. For a distributed storage composed of two mechanisms, those being capacitive and inductive, the equations for the overall transfer analysis are rather daunting. It is much better to consider the total energy storage within the system, and then lump that into a worst case analysis of effect. This is made easier by the fact that both mechanisms are lagging mechanisms.The graphs are rather interesting, too bad they cannot be posted here. I'd post the relevant equations, but you seem to have serious issues with equations being posted on a technically oriented forum..??
CJ: ""Let me quote a statement from the published paper:
"The shape, diameter & spacing of the conductors and shields determine the capacity between them. Coaxial cables are a special application version of a single shielded conductor and may be treated in the SAME way."""Pulling out of context quotes like this is useless. From your quote, I can't tell if they are talking about the current carrying capacity, the capacity of the wire as a tension member, or the capacitance. Nonetheless, your understanding of free space permittivity, propagation, and coaxial propagation needs to include all aspects of e/m theory, not just culling out of context things which were simplified for the reader within a specific context.
CJ: ""A bunch of formulae would not necesssarily help in situation like this where the original poster was seeking for simple answers.""A formula was required to explain to you where you erred in vacuum capacitance vs a non zero mass dielectric. A formula is required to determine the differential localization sensitivity of humans with two channel stimulus.
Formula's can be our friend..but you must use the correct one..
Cheers, John
Hi.AA is not a scientific/technical institute. It's only a techno chit-chat space despite PHP being more technically oriented as many our readers want to learn yet not technically knowlegeable enough.
That's why I always take the simple way to try to provide easier comprehension for our less technical readers. This complicated subject is a good example whereby I employed the published data of insulation dielectrics commonly used to build wires & cables,in order to provide a simplified perspective how the cable sonics may be affected.
Of course, there are technically better or more thorough way to doing so which I never dispute. But I am NOT "incorrect" as you keep on pushing it. For AA readers, I believe my simplified way should be adequate.
We all know inductance, capacitance & resistance (L, C, & R) are the fundamental properties of any AC circuits, which surely include audio interconnects. But instead of putting these complex factors to make it more complicated for our readers, technically enough or not,
to understand the sonic issue of a wire or cable, I only use "half the physics" - skip them & use insulation dielectrics, which are also valid properties of a insulated wire or cable to give another view angle for our readers.Mind you, you are pretty academic. You apply formaulae yet you don't seem to explain why & how you use them.
Let me go back to your assumption that a coaxial cable with theoretically vacuum as dielectric, will provide light speed transfer of the signal. I doubt very much despite whatever formaulae
you put forth to me.You still fail to explain why & how these formaulae you suggested work to support your assumption.
Let me reiterate my point: a coax is by itself a capacitor, with its centre conductor as one pole & the outside shielding as the other pole of the cap when AC or DC pass through it. Its capacitance can be expressed as the formula I already stated in my past post.
Being a capacitor, it got complex impedance, with resistive, capacitive & inductive, variable at selected frequencies. Energy loss on the signal transfer is inevitable.
So how can the wave still travel at light speed as if it is a perfect zero-loss media even your assumption of vacuum dielectric stands.
This is only logics, I don't care what formulae you use.
c-J
PS: "capacity" in my quote means capacity of the wire or cable
is the overall capacity as used as used as a current carrier.
CJ: ""AA is not a scientific/technical institute. It's only a techno chit-chat space despite PHP being more technically oriented as many our readers want to learn yet not technically knowlegeable enough. ""It's much more than that. It is a hugely hostile chit chat space.
Some of the readers do understand the equations, though.
cCJ: ""For AA readers, I believe my simplified way should be adequate.""
For some, you are correct.
CJ: ""But instead of putting these complex factors to make it more complicated for our readers, technically enough or not,
to understand the sonic issue of a wire or cable, I only use "half the physics" - skip them & use insulation dielectrics, which are also valid properties of a insulated wire or cable to give another view angle for our readers.""Neglecting the magnetic field means it is not possible to calculate the propagation speed. That distributed inductance is an absolute requirement to determination of prop speed.
CJ: ""You apply formaulae yet you don't seem to explain why & how you use them.""
I did explain. You either didn't understand, or you glossed over the explanation.
CJ: ""Let me go back to your assumption that a coaxial cable with theoretically vacuum as dielectric, will provide light speed transfer of the signal. I doubt very much despite whatever formaulae
you put forth to me.You still fail to explain why & how these formaulae you suggested work to support your assumption.""
I told you. Work out the math.
The formula exists to determine the inductance of a coaxial cable with an inner OD and an outer ID. Calculate it for any dimension coax at all, and use an μ r of 1.
Then use the formula for the calculation of the capacitance of that same coax using ε r of 1.
The, use the equation V = 1/ √ (LC).
You'll find that the velocity is the speed of light.
Put it into an excel spreadsheet...then vary either the inner OD, or the outer ID..and watch the prop velocity..
It remains the same..it is invariant w/r to the size of the coax.
Then change the dielectric constant. You will find that the velocity in this coax will follow exactly the formula for free space propagation in that media.
Why you do not confirm this for yourself, I have no idea.
But the equations are there, they are real, and they work.
If you need help with the equations, just ask.
CJ: ""So how can the wave still travel at light speed as if it is a perfect zero-loss media even your assumption of vacuum dielectric stands."'
Do the math..it works.
And, it is verifiable. It is (and has been)easily confirmed using tdr.
CJ: ""This is only logics, I don't care what formulae you use.""
That you don't care about the formula is something you've made quite clear. However, it is inaccurate and illogical to ignore 6 decades of e/m theory and it's results. That is what you are doing here. It is unfortunate that you choose to not let the facts get in your way.
As I said...I can only show you the door..your refusal to go through it is your issue, not mine.
Cheers, John
PS..obviously you need a lot of help here. (Your welcome)
Here's the simple equation, maybe you'll try it??Prop delay of a coax:Note: The equation has also been simplified for the reader, the removal of μ in this equation means it is only applicable for media with free space permeability..and it only applies to a coax. Changing the geometry, such as offsetting the center conductor or going with parallel wires or ribbons means this equation is useless.
B = 84.72 * 10 -12 √ ε r seconds per inch.
Now, Speed of light is 299792458 meters per second
there are 39.3700787 inches per meter.
Multiply SOL by inches per meter, you get:11802852665.1264446 inches per second. Now, invert that to get to the units of the prop delay from the previous equation...
1/11802852665.1264446 =..ta da..84.725280266750 * 10 -12 seconds per inch.
Now, you could try calculating the inductance and capacitance, then the prop velocity, as I suggested (and you ignored).
L = length(inches) * 5.08 * 10 -9 ln(outer ID/inner OD)
C = length(inches) * 1.41 * 10 -12 /( ln(outer ID/inner OD))
You know the prop velocity equation..
.
You need to learn the topic a little more..this stuff:
CJ: ""What is a "free space velocity of the dielectric"? Where can I find your back-up explanation "that if a coax is made with vacuum as the dielectric" in your above statement ????????
How can you expect anybody to understand what you meant w/o your
back-up explanation?First off, a coax always comes with a dielectric. Your "IF a coax is made with vacuum" does not exist & your reasoning is moot.
I already stated clearly an ideal wire is a bare wire & there will be very little propagation delay in free air. In vacuum, the wave will travel in light speed along that wire. The idea is exactly the same as you justed posted.
However, your statement: "if a COAX is made with vacuum as the dielectric, the prop velocity of that coax will be the speed of light" is very questionable.
What is a coax? It comes with an overal surrounding shield ideally equi-distant to the centre conductor from all side. This is a capactor by itself due to its construction, regardless the dielectric is a realworld material or a theoretical vacuum as you suggested.
Its capacitance is given by the formula: c=7.36x(e) divided by Log10 D/d where e is the dielectric constant & D is the outside diameter of the coaxial cable (includes the shield) & d is the diameter of the centre conductor. Unit is pF/ft
With capactance involved, how can you expect light speed transfer of a signal along a coax even with theoretically vacuum as dielectric?""
Wow..please find a text, you are rather confused.
1. Free space velocity of a dielectric is the speed of propagation of an e/m wave in that dielectric.
2. The speed of travel of a signal in a coax is the same speed as that of free space.
3. Vacuum filled coaxial cables are a dime a dozen in the world of high energy physics.
4. A signal does not travel along a "wire". It travels along two wires, both of them together form both a capacitor and an inductor. Or, in free space, as a result of e/m wave propagation.
5. A coax forms a capacitor and it forms an inductor.
6. The velocity of propagation along a coax is directly related to the inductance per unit length and the capacitance per unit length. Do the math...calculate the inductance per foot, and the capacitance per foot, then the prop speed. You will find that vacuum coax (which is used in some parts of the world of science), and even nitrogen filled coax (which is a staple for high power rf coax), has prop speeds approaching C.
I'll touch on the rest of your somewhat haphazard post tomorrow..in the meantime, please pick up a good book on the subject, Jackson maybe, or Becker..
I can only but show you the door..
Cheers, John
of relevance to what we hear, are we to infer that those are the only properties that have relevance to what we hear? If not what other criteria/properties need we consider?Also, even in the case of capacitance and inductance should we only be concerned with the absolute values of these properties (for that matter, in the case of cables, does the concept of absolute values even make sense?), or are there other considerations, e.g. a concept such as quality perhaps?; I'm thinking of the analogy to electronic parts where it is generally accepted that not all, e.g. capacitors, are considered equal, some claimed to provide superior sonic results, etc. (in any event clearly there are multiple types of capacitors, and I assume there are measurable properties to differentiate them).
Finally, when you say "You may be unable to understand what or how to measure, that is your limitation, not mine", are you implying that you possess definitive knowledge to associate objective measurements and/or other artifacts with subjective performance for cables?
Such a body of word would represent the tantamount of discovering the Holy Grail, at least for many audiophiles.
If so can we expect publication anytime soon?
bjh: "" are we to infer that those are the only properties that have relevance to what we hear?""
The only things important are R L and C for bulk cables.UNFORTUNATELY, all three are rather complex entities.
R and L vary with freq, skin effect. C is also, but it has many issues like soakage as stuff. So the quality of the dielectric is a big mush..until test capability is able to see the non linearity vs time for capacitors, the whole da thing is gonna be nuttin but hand waving. The basic stuff that was done years ago on caps, like that marshall article were very good, but don't go into real qualitative analysis, just point out the diff.
bjh: ""Also, even in the case of capacitance and inductance should we only be concerned with the absolute values of these properties (for that matter, in the case of cables, does the concept of absolute values even make sense?), or are there other considerations, e.g. a concept such as quality perhaps?""
RLC are all relative, so abs val is to be considered with respect to the load that is being driven.. L and C multiply to a constant, this constant changes with dielectric, which also can be frequency dependent.. C has a quality issue as well.bjh:
""Finally, when you say "You may be unable to understand what or how to measure, that is your limitation, not mine", are you implying that you possess definitive knowledge to associate objective measurements and/or other artifacts with subjective performance for cables?""It's easy to calculate out how the R, L, and C will cause changes in the waveforms, both for ITD and IID from a simple linear vantage. More complex issues are related to power dissipation into the cable resistance feeding a branch load, with that weird A 2 plus B 2 term, the 2AB..and, I'm wrestling also with a concept called inductive shedding, the ability of a hf waveform to zero out the inductive energy storage of a lf waveform, both via skin decimation, or flat out current squared terms. Something doesn't seem right in the energy balance, so says my gut. Working out those equations currently.
The real problem stems from determining the level of audibility of those shifts. We are sensitive to those parameters depending on where the image we wish to create is. I've seen no real research which addresses our sensitivity to those parameters in a differential manner. Most of the research is either shift one for threshold detection, or shift one with the other constant. But not really shifting both in configurations which are real world stimulus.
It is easy to measure how the cable parameters will shift the information. It requires some rather hairy, low inductance special resistors and the ability to detect small temporal shifts for reactance, some small amplitude shifts for resistance. But that technology is easily within grasp.
The real problem stems from understanding how we perceive the shifts. There, unfortunately, little work is evident in the high end world with respect to how we image.
bjh: ""If so can we expect publication anytime soon?""
I post a lot of this stuff on the forums, but absolutely nobody seems interested in persuing it. As I have a life, a job, and a honeydo list of several hundred (it seems) items, I would not be publishing anytime soon.
Got the kitchen functional now, so at least I can begin the work of setting up my basement lab in the next year or so. It's suprising how slow the detail work at the end of the job is.
Cheers, John
best of luck with it. I certainly look forward to seeing some definitive results fromthe biggest pile of
technical (wire related) erudition I have read in a while. :)
bjh: "" erudition""What a nice word used to describe a whole mess of "garbage"..
Some of the concepts are not easy to explain..keeping it as simple as I've been doing doesn't do the subject justice.
I kinda wish I could post the graphs here..and I wish I was better at three d excel spreadsheets. I hate having to write my own code to display the stuff in 3-d. The autoranging functions in visual basic can be a PITA.
Cheers, John
I don't have enough scientific knowledge or materials background to be familiar with this stuff, but the way you explain it makes sense.BTW, the original poster was talking about interconnects, not speaker cables.
Clifff: ""BTW, the original poster was talking about interconnects, not speaker cables. ""My initial post simply described the term non-sequitur, which CJ responded to in a hostile fashion. I had not intended to plop directly into a treatise of maxwells equations. That only happened when he started smacking me in the face with an inaccurate use of constrained equations.
The world is not capacitance alone. Nor is it coaxial alone.
It is way more complex. And requires a complexity commensurate with the issue.
Cheers, John
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
