Thanks for tolerating my quirky humor, Sy. I'll get around to doing the test. I'm collecting various older speaker cables and lamp cord at the moment.
Actually, I could probably attempt to prove my point by 'pretreating' a speaker cable to the point where the conductors are very seriously corroded, say by soaking them in a brine &/or acid or alkali bath for a period of time. The UUT may then be more deteriorated than speaker cables usually get, but isn't the point, at the end of the day, whether measureable interstrand rectification even exists at all in speaker cable?
Actually, I could probably attempt to prove my point by 'pretreating' a speaker cable to the point where the conductors are very seriously corroded, say by soaking them in a brine &/or acid or alkali bath for a period of time. The UUT may then be more deteriorated than speaker cables usually get, but isn't the point, at the end of the day, whether measureable interstrand rectification even exists at all in speaker cable?
Last edited:
Excellent.. My, those pictures look STRANGELY similar to the graph I produced on this thread...
Note that when you use the 8 ohm T-line, there is no delay to speak of, just the 15 nSec.
Now, instead of your infinite slew, drop the rate to 1 nSec, 2, 5, 10, and 20 nSec. Notice that the delay times still remain the same relative to each other. However, you will begin to see that the steps are going away. NOTE that your model is INDEPENDENT of your slew rate. It's just that you can easily see the jump with fast slew..
Let's try a real cable. A zip line 20 feet long, with an effective dielectric coefficient of 10. the Prop velocity is V = 1/sqr(EDC), or v = .316 C. 3 nSec per foot, or 60 nanoseconds transit. 4 times the 15nSec you used.
So now you're running what, 4 uSec for the 100 ohm cable? When you run 2 ohm load and 120 ohm cable, say, 6 to 8 uSec? Versus zero delay if the speaker bumps to 100 ohms..
And this is for ideal resistive load and zero impedance output. With real world values of reactance on the load and impedance at the amp, what numbers can we realistically envision? 10 uSec, 20, 50??
What is important is the difference between the load values one can reasonably expect among speakers, what those loads do to these delays, and if they exceed JND for image localization.
He does indeed seem to be claiming this. But as I stated, using a load higher than the line is a very poor choice, as it presents oscillations which are meaningless to human hearing.
No, it is entirely in agreement with my statements..
If the line matches the load, the only delay in the system is prop delay. And as I have said all along, prop delays are trivially small. 15 to 50 nanoseconds??? No brainer.
It is only when the load is tragically lower in impedance than the line that the settling time rears it's ugly head.
Cheers, jn
This post clearly indicates that you do not understand what is being discussed by me. Yet, it did not stop you from elaboration.
My previous post explains the distinction between settling time of a mismatched line to load system, and one which is fully matched. Please ask questions of me instead of going off on tangents..
thank you.
jn
Your attempt at measuring the resistance of a corroded cable at the ppm level to prove rectification or directionality will fail miserably. Any difference you find will be a result of test error.
The only way you will be able to prove anything of this nature will be by the use of AC signals of sufficient frequency to distinguish the interstrand breakup of eddy currents. And at that, it will only be possible to see the inductive change resulting from the breakdown of the skin effect.
Since the inductance of a solid conductor at DC is 15 nH per foot, this is the upper limit of inductive change that you will be able to see. Given the inductance per foot of a zip is in the 180 nH per foot range, you are trying to notice an inductance shift of about 10%. You will need to construct a specific cable to do measure the loss of internal inductance.
Take your zip apart. Use ONE of the greenish conductors, and place a copper braid around it forming a coaxial cable. Heat shrink over this to stabilize the external inductance. This coax is the best shot you have at measuring anything.
Now test it. Do a frequency sweep from100 hz to about 100 khz.
Push an ampere at any frequency into a good 4 ohm load, and look at the spectra of the output.
Interstrand breakdown will produce even order harmonics.
To prove your results, make two of these cables with good wire. Then bake the livin heck outta one..then repeat measure both.
Cheers, jn
Last edited:
If properly soldered to end terminations, I see no possible way to sustain any potential between strands of multistrand wire. JN's example of course is possible but I would like to see a detailed analysis of how much potential could arise due to this. I would take some crap wire and deliberately not connect half of the strands at each end. Lots of strands in that 0000 welding cable.
Last edited:
Agreed.
It is important to remember that it is not the steps, nor the slew rate that is important here. It is the system delay as a result of the mismatch line to load, given that our speaker loads vary hugely.
If I could have modelled it easily to show the delays without the infinite steps, perhaps everybody else would have understood the issue. Sigh..
Unfortunately, the simple lumped model doesn't directly show the zeropoint inflection that occurs when line equals load.
Cheers, jn
We went through this earlier in the thread. One indeed has to have half the strands break at one end, the other half break at the other end.
Only by forcing skinning can it be done. As you say, properly soldered and DC, there is no way.
edit: skin effect is the result of Faraday's law of induction applied to the conductor, a consequence of changing the transport current of the conductor. It creates toroidal currents which enhance current density at the outer region of the conductor, and reduces the total currents at the core. The net effect is to force the transport current to the outer surface, or skin, of the conductor. Interstrand insulation prevents these toroidal currents. A corroded stranded wire will "attempt" to act like a litz.
Um, I already stated it.
15 nH is the total internal inductance. And, that is the only thing.
The coax method is a method of reducing the rest of the inductance while keeping external noise out as well.
Jn
Last edited:
??? If the rectifying system is Cu-CuxSy-Cu I don't see the assymetry. This experiment has no way to get at the "junk" layer by itself with an ohmic connection.
I'm passionated by music. (My mother was a pianist)
As a research and development engineer, in a hifi equipment company, i was passionated by all the technical aspects witch make this magic: Make believe to the presence of musical instruments and musiciens in your living room with such a garbage of carbon, Silicium, Coper, Magnets, partial technical knowledge, luck and other paper cones glued together with economical preocupations. Trying to minimize the luck factor and to increase the knowledge's one.
Part of our mission was to help marketing in producing technical arguments (curves, words and formulas) to convince the naive and gullible customer that our products where constructed by God itself. It was very funny to tell fairy tails with real measurements.
As a sound engineer both in music, concerts and movie industry, i was involved in producing realistic sonic landscapes with expensive garbage equipments in various bad acoustics environments.
As an old man, i've read and listened so many crazy things even from respected sound engineers ...
One day, if i have time, i will write a web page on my site to demonstrate how my supermarket electric wires are superior against all existing others.
If you glue that together, you will understand some of my reactions and positions.
As a french guy, my English is far from satisfy the hifi minimum requirements. (sorry if some misunderstandings or lacks of nuances from my side). But i had read your posts with much of interest, and read hundred pages about some technical questions you talked about since two days, i love to learn new domains and correlate them with my too little knowledge.
This localization and "sound in space" question is passionating me. I've read thousand of books and research white papers about this subject. Used very interesting and exotic studio's stuff to manipulate sound space durin mixing process.Worked a lot on loudspeakers horns filters and enclosures. In the time domain too.
I wonder this incredible and mysterious instrument witch is our ears witch capture pressure variations and our brain witch treat them when it comes to listen to sounds and music.
And the mystical way are build our senses ( logarithmic and differential) while we all think in such a linear and integrating way.
But that's if far out off topic ?
Last edited:
Find a picture which details the toroidal currents that flow when the transport current changes. Notice that the currents have to flow across strands. If there is no interstrand conductivity, there is no skin effect. Like litz.
The exclusion of current from the core of a conductor due to skin effect is magnitude (of rate of change) based. In other words, it happens in both directions of the current. Hence, it is 2 times frequency.
edit: for velocity V, it is fraction of light speed...sorry, forgot to mention that...
For a coaxial cable, the general case for prop velocity is V = 1/sqr(epsilon times mu). Since most dielectrics have a mu relative of 1, the equation becomes:
V = 1/sqr(epsilon) (edit..epsilon is the relative dielectric constant of the insulation)
This equation is accurate for any constrained transmission line, so is useful for cables made using flat conductors as well, as long as the dielectric is very thin in comparison to it's width.
Also used is : V = 1/sqr(LC). just be careful of units. (edit: this is actual velocity, not fraction of C)
For regular wire pairs, the magnetic field is not constrained like the coaxial case. So you cannot use the simple V = 1/sqr(epsilon). It is necessary to use either the LC equation, or the "effective dielectric constant".
For my needs, it is useful to use "effective dielectric constant" in place of "dielectric constant" when considering cables which are like zip cable. It is a hybrid entity which considers both the capacitive as well as inductive energy storage of the wire. And, it is accurate for velocity as well..
In all cases, the equation:
LC = 1034 EDC L in nh per foot, C in pf per foot.
describes the relationship between the inductance and capacitance of any wire pair.
If you take the measured values of L and C, and use the LC=1034 EDC equation, you can derive the EDC, and 1/sqr(EDC) gives the prop velocity.
Cheers, jn
Last edited:
As I was replying to SY's comment on something MT said, why should I consult you? As it happens, I believe you and I are probably not too far apart on this particular topic, but so what? If I wish to "go off on a tangent" (in your opinion) then provided it is within the general topic of the conversation (speaker cables?) and the mods are happy then I am free to do so.jneutron said:
John, please don't jump to the conclusion that if one of my posts happens to immediately follow one of yours that I am replying to you. Time delays insert a degree of randomness. If I happen to say something which differs from you in some detail please don't assume I am arguing with you - in some cases I might not even have seen your post first. I might be arguing with someone who is much further away from my own opinion.
Let us suppose that the resistance of the cable varies at 2f. (I am not saying that it does, but let us assume that it does). This is equivalent to multiplying the signal f by 2f. The result will be f and 3f components.Esperado said:
Does the resistance vary? I am not sure it does. Skin effect depends on frequency, not amplitude. So maybe I was too hasty in post 517.
- Status
- Not open for further replies.