The Science of Cables

Ha ha  "dropped the ball on gravity" 

I don’t want to bring anybody down but John Archibald Wheeler, Charles Misner and Kip Thorne wrote the book on gravity... a long time ago. Almost 50 years ago, actually. My, how time flies! Let’s just say gravity is not what you probably think it is but what it is is probably understandable to most people who aren’t English majors or audio engineers. 😀 I’m afraid you’ll have to look elsewhere for something that’s still a mystery.

I have heard subtle differences between how different speaker cables sound in an A-B demonstration at an audio club and the difference was above a threshold of placebo effect. Interconnect cables can sound different if capacitance is not accounted for in their design and the context of input impedance. However, there is some bad physics adduced in the marketing of very expensive cables. Here are two examples.  The first  is skin effect, the concentration of current towards the surface of a conductor as the frequency of alternating current increases. There are some speaker cables which endeavor to address skin effect in their design: either by making ribbon cables which are thinner than skin depth at higher audio frequencies or by litz wires which bundle insulated individual strands of wire which individually are thinner than skin depth. But nobody has made any calculations to determine whether such designs make a difference in whether anyone could hear treble roll-off caused by the skin effect in a speaker cable. So let us consider a set of 5 foot long cables of 8 gauge copper wire connected to a pair of speakers with 4 Ohms impedance. The total of 10 feet the audio signal must pass through the two 5 foot speaker cables has a DC resistance of only about 0.006 Ohms. At 20 kHz, skin effect concentrates the current towards the surface of the cable reducing the cross-sectional area which carries the current and the resistance increases to 0.012 Ohms. Compare that to the 4 Ohms speaker resistance in the case of a magnetic planar speaker which has negligible inductive or capacitive reactance and the effect is slightly over one one hundredth of a decibel roll-off at a frequency almost nobody can hear. Either the cable designer has too shallow an understanding of skin depth to calculate this or they know the effect is inconsequential but choose to capitalize upon their target audience's superficial understanding when they advertise how they are doing something about the skin depth problem which does not really exist. Another questionable matter is the alleged grain structure of copper wire emulating semiconductors at the interfaces between grains making the resistance non-linear with respect to applied voltage at low signal. Nowhere in any graduate school physics or electrical engineering texts is there a non-zero derivative of resistance with respect to voltage or current in Ohm's law for copper wire and if this law applied to low signal voltages antenna cables from a receiving antenna atop a tall tower to an FM tuner would have nonlinearities which would generate Fourier RF harmonics that would disrupt any frequency of a radio station inducing only micro-Volts in the antenna. Another issue is slight nonlinearities in the dielectric which insulates cables. This becomes insignificant at the few volts in a speaker cable and an interconnect cable not suffering an electric field which makes the alignment of dipole molecules change the dielectric constant at much higher voltages. Also since the electric field in a cable is parallel to the cable in a conductor, there will be no component of electric field in the insulator.  

drbarney118 posts02-16-2019 4:19pmI have heard subtle differences between how different speaker cables sound in an A-B demonstration at an audio club and the difference was above a threshold of placebo effect

>>>>A threshold of placebo effect? Whoa! I did not know that.

Thank-you  taras22. As for eric_squires all I get from you is an appearance of personal jealousy.  Dismissing a detailed argument as irrelevant shows no analytic skill and is a lazy thinker's way of trying to dominate a conversation.  You have been well and truly one-upped and the more you complain, the worse you look.