Are there any constants in speaker wire designs?

"You are correct about skin effect. Skin effect is a phenomenon that you tend to see at microwave frequencies."

This is incorrect. At microwave frequencies skin depth is in order of um. At audio frequency of 20kHz largest copper wire that has still the same resistance for DC as AC is gauge 18. Please check skin depth calculator here:

http://daycounter.com/Calculators/SkinEffect/Skin-Effect-Calculator.phtml

Skin effect is very pronounced at video frequencies. That's why cables are made of cheap metal silver plated (signal travels on the surface).

Skin effect allows for shielding. Interconnect for instance cannot be possibly protected from electromagnetic pickup of high frequency signals by non-magnetic shield. What really happens is that shield passes these high frequencies and they are induced in the cable, but because of skin effect they travel on the outside of the cable - shield. Internally field is zero as long as wire is symmetrical. Without skin effect aluminum foil or copper braid would not shield higher frequencies (would protect only for capacitive pick-up). Shielding is very complicated. Shield is carrying externally induced high frequencies on its outside while at the same time common mode high frequency signal noise travels on the inside of the same shield. At lower frequencies shield does not protect at all but wire is to short to become effective antenna (starts at 1/10 of wavelength)

Audio cables are much more complicated than just RLC. If I remember correctly Muralman1 uses in his design cable different metals for signal and Ground wires. You cannot explain in terms of RLC how different metals change the sound.

PaperW8, I mentioned the inductance / capacitance issue with speakers because, as you probably know, some manufacturers are purposely designing cables to have abnormally high values of one characteristic or the other. Some high capacitance cables have even been known to destablize some poorly designed amps, not to mention causing high frequency roll-offs that people with overly bright speakers seem to be drawn to. Nonetheless, I think you and I are on the same page.

Mjordanas, I'm sorry, but changing a power cord is extraordinarily unlikely to change the way a DAC works, especially in a way that is beneficial. Focus would imply a measurable reduction in noise or distortion, which is beyond the capability of a completely passive conductor.

Kijanki: it is a true statement that signals attenuate within a conductor as you get farther away from the surface of the conductor into the interior. I didn't mean to suggest that skin effect doesn't at frequencies below microwave but that it is at higher frequencies where it becomes a bigger deal.

You mentioned skin effect as being significant with video signals. Video signals operate in the MHz range, which is below what is typically considered the microwave frequency range. I do agree with your suggestion that skin effect can be significant for frequencies in the MHz range. At video frequencies the skin depth is very thin, so the silver plating can be economically applied at thicknesses greater than the skin depth. Silver plating is a less effective cost-saving strategy for audio frequencies because the skin depths at audio frequencies are much larger.

There is a relevant figure of merit called the 1% depth of penetration. The 1% depth figure indicates that point at which the signal magnitude is about 1% of it's surface value. It is about 4.6 times the skin depth.

In general, skin effect is significant when the skin depth is small compared to the size of the conductor. At audio frequencies, the skin depth is going to be on the order of 20 mils, so I would think that for significant skin effect, you're probably looking at conductors that are on the order of at least 0.1 inch. That would be more like AWG 10.

There are other effects that are significant when thinking about signal propagation through a conductor (you had me going to my old textbooks to look this stuff up). For example, as the magnitude of the signal decreases the relative phase of the signal also changes. I believe that at the skin depth, the signal is about 180 degrees out of phase with respect to the signal at the surface. Also, when you have multiple conductors, there are proximity effects where the electromagnetic fields of the conductors interact and can effectively reduce the skin depth. Skin effect also increases the impedance of the conductor to signal propagation, although I am unfamiliar with the formula that was cited in the web link that you posted (I took a look at it and it looks to be a pretty good link). However, the skin depth calculator is correct, so I will assume that the AC/DC resistance ratio presented is correct as well.

Is any of this stuff audible, significant or even detectable at audio frequencies? It's impossible for me to say without data, so I tend to not tell people that they aren't hearing what they say they are hearing. I question how significant this stuff is at audio frequencies and because of the amount of hyperbole that has so come to characterize the audio biz, I am skeptical of claims that rely upon nothing but buzzwords. The thing is, if I spent big money on cables, I would have a vested interest in convincing myself that there really is a big difference because I would have a commitment to feeling that I haven't wasted my money. It would be nice to see some real data on this stuff. In my mind, it would make all this talk of "focus" and the like, a lot more credible. As I stated, the amount of hype and questionable "audiophile reviews" just hurts the credibility of the industry in my mind.

Paperw8 - according to mentioned skin depth calculator 20 mils corresponds to gage 18. Skin effect is therefore not existent in interconnects but might with speaker cables. Using thick wire lowers resistance but also inductance. The same happens with stranded wires. Isolating strands doesn't help them being in each other magnetic field (doesn't reduce overall skin effect) but placing strands on the hollow core or flat woven pattern does.

I understand that you are sceptical about skin effect in audio (as I am) since we need couple of dB to notice volume change but on the other hand fraction of dB on the tone control can be perceived.

All cable companies go toward similar solution like flat cables (Nordost) or hollow tube cables (AQ, AZ). I tend to trust them and suspect that they don't do this for marketing purpose alone since most of customers have no idea what skin effect is. I can hear specific difference between speaker cables while other tell me I must be self hypnotized and that cheap Home Depot wire is good enough.

I don't know how to measure focus or soundstage depth or width but it exists and is affected by something. Can this something be simply measured by relation between R, L and C.
Can we say that all speaker cables that have exactly same RLC will have exactly same sound (focus, soundstaging, etc.)? What about R,L or C vs frequency - it might be complex relationship?

09-05-10: Kijanki
I don't know how to measure focus or soundstage depth or width but it exists and is affected by something. Can this something be simply measured by relation between R, L and C.
Can we say that all speaker cables that have exactly same RLC will have exactly same sound (focus, soundstaging, etc.)? What about R,L or C vs frequency - it might be complex relationship?

"focus" and "soundstage depth" are subjective evaluations - you can't measure that kind of stuff. but you can measure electrical characteristics that have relevance in cable performance. the measure that i would generally think to be of significance is resistance, maybe measured at different frequencies. this could give an indication of how transparent a cable is across the audio frequency spectrum.

for interconnect cable, there could be capacitance in the dielectric material between the core and the screen; you can measure that. even if they just report the data and don't tell you how to interpret it, at least then you could find that kind of stuff out and then you have data that you can use to evaluate the cables. it would be useful for reviews to provide information about the magnitude and phase response of cables.

i'm not saying that there is no role for subjective evaluations, but it would be useful to see whether objective data supports the subjective claims. a non-audiophile like me would be inclined to use the information to cut down the number of candidates that i might consider.