[Tom M]

Quote:

Originally posted by Joe Bloggs If they are really frequency dependent... Then, somebody show me a 'capacitance response' or 'inductance response' graph... J.Y. can you link to the article?

sorry bloggs but you are wasting your time with that one. Nobody will show you any graphs. I don't know why. Either they can't or they Won't. I find this just as confusing. It might just be the mystery that makes better cables sound better. The old placebo effect

 

[Mastergill]

There's no mystery with cables, there's just things that actually cannot be mesured and the ears are more accurate than any mesuring device. There's lot of things with sound and music that cannot be mesured, the most obvious is the tonal quality of an musical instrument. Ask a techi guy to mesure what make a Stradivarius sound like vs. an ordinary violon and look at his face, that's very funny.

 

[AnsBjork]

Quote:

If they are really frequency dependent... Then, somebody show me a 'capacitance response' or 'inductance response' graph...

As I said I am no expert at electronics, but I was recalling that information from my electromagnetic course at university. Maybe a general search (not cable related) on internet could help you find the information?

 

[dvw]

joe bloggs is correct. Capacitance, inductance and resistance are not frequency dependent. I think you are thinking about impedance which is grequency dependent.

 

[fewtch]

Quote:

Originally posted by Mastergill There's no mystery with cables, there's just things that actually cannot be mesured and the ears are more accurate than any mesuring device.

Oh? One can measure an 80 KHz tone, but try hearing it

... Also, one can measure a 0.05 dB difference in volume, but it can't be heard as a variation.

Actually, the accuracy of human ears (in dozens of different areas, not only frequency response) is well known and has been meticulously charted and plotted out by people who are interested in such things... I have no links and am not interested myself, but thought maybe you'd like to know.

 

[Joe Bloggs]

I asked about this at hydrogenaudio.org:
http://www.hydrogenaudio.org/index.php?showtopic=14232

Made quite a few people amazingly confused, but the consensus at the end is the same: capacitance, inductance and resistance do not change with time. Impedance and phase response do. The best thing to do is really to just keep capacitance, inductance and resistance all at a minimum.

 

[Mastergill]

Quote:

Originally posted by fewtch Oh? One can measure an 80 KHz tone, but try hearing it ... Also, one can measure a 0.05 dB difference in volume, but it can't be heard as a variation.

C'mon, you know i was talking about frequency we can hear.

The accuracy of a well trained musicien ear is far better than mass people earing including myself, do you think the guy tune piano with a meter ?

 

[AnsBjork]

This link is a study by IBM on the effect of frequency on cables caracteristics illustrating what I've learn in my electromagnetic courses. They are also speaking of the "mythical' skin effect.

The study is based on hi-frequncies and close proximity conductors so it may not be directly transferable to audio cables, in fact in may not be applicable at all for our discussion... But who knows?

Not me for sure!

http://www.sigda.org/Archives/Procee...files/18_3.pdf

For those of you who will read this paper, I think you will get a glimpse of the complexity of a quite simple phenomenon: current flowing trough a cable. The just imagine how complex it would get just to compare the musicallity differents cables on different systems!

Our ears may not be the best instruments to measure sound, but what we have between our ears (ie: brain) is still the best sound analyser I know of.

We don't need to measure inaudible sounds, we need to know if a recorded instrument sounds like the real thing. That's a whole different problem.

 

[Tom M]

Quote:

Originally posted by Budgie Really? I doubt that. Things are routinely measured that are far beyond the ability of human senses. The only thing that is not measurable is the placebo effect.

I agree with budgie. Btw check your pm Budgie

 

[Joe Bloggs]

It seems that according to the graph on that paper, skin effect starts to affect R and L at 100MHz, and even then it might be because of the interaction between the dense forest of tiny wires and the power supply at different frequencies.

 

[AnsBjork]

Joe, I've read the posts on the other forum and they are saying a lot of different things but they are mostly talking about *ideal* elements like the ones used in school textbooks of general electronics. Is a cable an *ideal* capacitance? Maybe it can be approximated like one but we are talking about small difference here.

It is like using Newtonian physics instead of Einsteinian physics.

Again I'm no expert in the field so I'm in no position to argue.

 

[Joe Bloggs]

Quote:

Again I'm no expert in the field so I'm in no position to argue.

Then I'm sorry to tell you that I think you're not reading the info in that thread right

Seems like it's usually not a good idea to pick words and sentence fragments out of a technical paper or discussion and use them to support some point you have... usually it turns out the writer means something entirely different from what you think he means... at some point it's a much better idea to ask them questions directly and get a straight answer

Although your paper does seem to suggest that R and L can change with freq. in certain situations... like when the actual pattern of current flow is changing at different frequencies! Kind of hard to happen, though, when there's only one wire leading from A to B, don't you think?

 

[AnsBjork]

I hope I won't go too much out of thread.

First things first:
My point in this tread is that to describe cable characteristics we need more than the usual incomplete data provided by vendors or by hobbyists. I find that with the tools we have now, our ears are the best and only way to evaluate cables.

That’s the only point I was trying to make.

Secondly:
I did not quote that paper at all in my comments, so your "gentle" accusation is uncalled for. My comments were based on my general knowledge of electromagnetism and were formulated as a question and a possibility, not an affirmation (I don't have the qualifications like a mentioned a few times). The document I mentioned was to show that things can get more complex that we initially believe in a related field. It was to open our eyes to the possibilities. It is not a proof of anything.

This concept also exist in mechanics (hydraulics): resistance and capacitance are dependant of frequency because of friction. Frequency of resonance also exist in hydraulic systems. Friction also exist in electronics and from my studies in engineering I can tell you that the equations we use in mechanics are very similar to the one used in electronic. This is not a proof, only an intuition that make sense enough to investigate.

Last and the least:

Once, a long time ago, I've learn in my electronic courses that a LED offer no resistance to current. Later I've learned that in real life there is an associated voltage drop in LED but it was not mentioned earlier for "academic" reasons. So there can be differences between basic knowledge and advanced research. All the discussions in the treads are based on basic level electrical formulas NOT direct experimentation on cables; it doesn’t prove anything.

Also when I read argument on that forum like: "a capacitance cannot change because then we wouldn’t be able to write 100Fa on a capacitor" I see two things:
1) He/she is talking about capacitors not cables.
2) This is a rhetorical argument.
This is of course only one (loose) quote and does not represent the forum in a whole. Personally I'm not convinced that I didn't understand the tread; maybe it's because of my poor intellect.

 

[AnsBjork]

By the way, look at this web site. A lot of useful information and some words about cables sensibility to frequency:

http://www.rwonline.com/reference-ro...-lampen2.shtml

http://www.rwonline.com/reference-ro...n-July18.shtml

http://www.rwonline.com/reference-ro...08.15.01.shtml

Basically the paper is saying that impedance, capacitance inductance and skin effect are dependant of frequency but with more or less effect on sound depending on the parameter. Resistance is also affected indirectly by frequency. The guy has also a pretty strong opinion about audio cables...

Here are the credentials of the guy:
Steve Lampen is Technology Specialist, Multimedia Products for Belden Electronics Division. Steve holds an FCC Lifetime General License (formerly a First Class FCC License) and is an SBE Certified Radio Broadcast Engineer. On the data side he is a BICSI Registered Communication Distribution Designer. His latest book, "The Audio-Video Cable Installer's Pocket Guide" is published by McGraw-Hill.

Now let's try to focus on the thread.

 

[dvw]

AnsBjork

The IBM paper you cited is not really relevant to the cable. It is about modelling of interconnect on an IC. The IC is made of silicon (which is a semiconductor), and the interconnect is made of aluminiun and poly silicon. Because of proximity effect at very high frequency the RLC will change (layout dependent). Cable has no such power distribution limitation therefore will not affect the RLC.

Steve L's article mentioned only frequency dependent impedance not RLC. Impedance = 1/2/pi/f/c with capacitnace only.

Steve L's artilcle is pretty accurate if you read it carefully.