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What Electrical Property Governs Cable Design?

post #1 of 45
Thread Starter 

This question has been addressed in other threads in other forums, but coming to this site only recently, I find that most of the existing threads regarding this topic have digressed.  I am not an electrician, or an electrical engineer, just curious if some scientific principles can be applied to this discussion.

 

I would guess that the controlling electrical property of the cable is the overall resistance...connectors, solder, conductor all in the mix, and that lowest possible resistance in the cable system is desired for best SQ.  If this is true, consider the equation:

 

RESISTANCE = (RESISTIVITY x LENGTH) / AREA

 

Resistivity is a property of the metallic conductors in the system.

Length could be considered the length of the cable.

Area is the total cross sectional area of one conductor, which likely has multiple individual wires or strands.

 

Ignoring the influence of the connectors and the solder, and considering only the cable...

 

1.  The difference in resistivity between copper and silver is small...silver is a better conductor, but not by much.  If the resistivity of copper is 1.0, then by comparison silver would be about 0.95.  So changing the conductors from solid copper to solid silver and leaving everything else the same would lower the resistance by about 5%.

 

2.  Assuming the average cable is about 48" long, reducing the cable length to 36" (with no other changes) would reduce the resistance by 25%...a far more significant improvement, and presumably a far more cost effective solution than in point 1.  However, I do not recall ever having seen a claim that a shorter cable length improves the SQ.

 

3.  Similarly, an increase in the diameter of the wire would also decrease the resistance.  Increasing the diameter of the wire by 10% would increase the area by 21% and reduce the resistance similarly.  This could also be accomplished by adding individual strands of wire to the composite conductor,  Again, I have not seen any claims that using larger diameter wire or more wires in the cable strand will improve SQ.

 

What am I missing here?  Is the resistance of the cable (ignoring the other components in the system...connectors, solder joints, etc.) the controlling electrical property of the cable?
post #2 of 45

Assuming that the wire in the cable isn't made from Swiss Cheese and nothing is defective, the capacitance of the wire and impedance of the circuit (cans and amp) will cause a loss of high frequencies. Again, unless the cable is really bad stuff, it should not affect audio at all. I measured the capacitance of the stock cable on my Sennheiser HD600 and at 300 Ohms the affected frequencies are well into the spectrum of radio frequencies, not audio. The real affect would have to consider how it creates a load or tuned circuit to the output of your amp going to your cans. In this case is the capacitance enough to cause unstable behavior? Or considering the capacitance and the impedance of the cable (in this case resistance of the wire) along with the reactance of the cans (inductance/capacitance/impedance) forming a tuned circuit which in this case again will not affect audio, at all. IMO Silver is best used for killing mythical vampires. Copper is just fine.

post #3 of 45
Resistance, capacitance and inductance.

se
post #4 of 45
Quote:
Originally Posted by Steve Eddy View Post

Resistance, capacitance and inductance.

se

Makes better sense than some of the myth and magic that I've heard :D I just love it when I hear the one about a power cord improving the treble or soundstage.

post #5 of 45
Quote:
Originally Posted by zombywoof View Post
 
What am I missing here?

 

Subjectivists don't care about any of that. It doesn't matter how competent or broken a cable (or any other component for that matter) is, as long as their gut feeling is good.

They're not interested in high fidelity but in hearing differences.


Edited by xnor - 12/15/13 at 10:06am
post #6 of 45

Quote:

Originally Posted by zombywoof View Post
 

What am I missing here?
 
Originally Posted by xnor View Post
 

 

Subjectivists don't care about any of that. It doesn't matter how competent or broken a cable (or any other component for that matter) is, as long as their gut feeling is good.

IMO, they are missing listening skills. The psychology of audio is both enlightening as well as amusing. I find it facinating that human beings have a very brief period of audio memory, yet Subjectivists swear how they remember intricate details of impossible experiences and deny the science that allows them the devices that sparks their imaginations. I don't mind that they enjoy themselves but do not appreciate the spread of myths that misinform the uninitiated.

post #7 of 45
Quote:
Originally Posted by StanD View Post
 

IMO, they are missing listening skills.

I think it's not so much a lack of listening skills, but a lack of basic honesty controls.

 

"The first principle is that you must not fool yourself, and you are the easiest person to fool." -- Richard Feynman

 

 

This starts with trivial things like correctly matching volume levels (this may even be required for cables if they have enough difference in resistance) and ends with statistical analysis of full-blown double blind tests with many participants.

For example, if 100 people do a blind test with 20 trials comparing two identical components (so there is no difference at all, NONE) you will still get 3 people who succeed in the test from a statistical point of view!


Edited by xnor - 12/15/13 at 11:41am
post #8 of 45
Quote:
Originally Posted by xnor View Post
 

I think it's not so much a lack of listening skills, but a lack of basic honesty controls.

 

"The first principle is that you must not fool yourself, and you are the easiest person to fool." -- Richard Feynman

 

 

This starts with trivial things like correctly matching volume levels (this may even be required for cables if they have enough difference in resistance) and ends with statistical analysis of full-blown double blind tests with many participants.

For example, if 100 people do a blind test with 20 trials comparing two identical components (so there is no difference at all, NONE) you will still get 3 people who succeed in the test from a statistical point of view!

It is extremely unlikely that cable resistance will come into play, however, you are 100% correct about matching volume levels as that affects the way we perceive frequency response due to loudness contour (Fletcher–Munson curves). I didn't want t bring up the honesty issue as that's a quick way to get the flames burning. :blink:

post #9 of 45

There seem to be some rare cases where the stock cable actually measures a few ohms.

post #10 of 45
Quote:
Originally Posted by xnor View Post
 

There seem to be some rare cases where the stock cable actually measures a few ohms.

Defect? What brand what model? If the cans are 300 Ohms like an HD600, it may not make any difference in a change of loudness. A few Ohms and a few hundred pF of capacitance won't have any affect on audio frequencies.

post #11 of 45
Quote:
Originally Posted by StanD View Post
 

Defect? What brand what model? If the cans are 300 Ohms like an HD600, it may not make any difference in a change of loudness. A few Ohms and a few hundred pF of capacitance won't have any affect on audio frequencies.

At 300 ohms it won't make much of a difference, but it'll make a difference at 32.

post #12 of 45

Atm I only found ultrabike posting that his HD558 cable measured ~1 ohm.

post #13 of 45
Quote:
Originally Posted by SanjiWatsuki View Post
 

At 300 ohms it won't make much of a difference, but it'll make a difference at 32.

Probably that not as much as you may think as we hear in a logarithmic fashion. The cable would have to be 32 Ohms to make a -6 db loss,  a 5 Ohm cable resistance would  result in a -1.26 dB loss and a 1 Ohm cable resistance in  a -.27 db loss.  See the below equation.

20 * log(32 /( CableResistance + 32))

post #14 of 45

That could be enough to prefer it in a comparison, if we completely ignore that two headphones will sound (slightly) different anyway ... which in turn makes cable sound claims even more ridiculous.

post #15 of 45
Quote:
Originally Posted by xnor View Post
 

Atm I only found ultrabike posting that his HD558 cable measured ~1 ohm.

50 Ohms cans, so that would result in a -0.172 db loss with a 1 Ohm cable. I have a pair of HD558's and the stock cable which is very long measures at around 0.7 Ohms per leg which is more than 1 Ohm total for a loss of -0.24 dB, I just measured them. I also bought the optional shorter cable with a 3.5mm plug which should have a lower resistance. I use the shorter cable,mainly because of the plug size as well as the length is tidier. OK I just unplugged that cable, it's 0.2 Ohms. It's late and I'm not going to mess with my HD600's or Momentums. :D

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