Are there any constants in speaker wire designs?

09-01-10: Irvrobinson
Kijanki, skin effect isn't considered significant at audible frequencies. At 20KHz it'll be less than 0.2db, which is truly insignificant in the context of real speakers in a real room.

Strand jumping sounds like quasi-technical mumbo-jumbo to me.

You are correct about skin effect. Skin effect is a phenomenon that you tend to see at microwave frequencies. Your comments also point to one of the big problems in the audiophile game in general; there is too much BS in the selling of audio equipment. The reason, i suspect, is that most audiophiles know little about electronics and are therefore susceptible to marketing hype and "buzzwords". Add to it all, the "audiophile" reviews that you read by reviewers who often have undisclosed conflicts of interest that mean that they are really acting as salesmen for the vendors' products. For me, the net result is that I have become highly skeptical of the claims that I read. This loss of credibility, I think, is ultimately harmful to the industry.

Let me make a brief comment on you statement about the significance of inductance and capacitance in cable. Under the "transmission line" model, a wire can be characterized as a network of inductive and capacitive elements; then you analyze the signal distortion effects of this model. However, the transmission line model is also one that is primarily observed at microwave frequencies. At audio frequencies, the wire is basically a resistive element. But speaker cable might run on the order of 5-10 ohms/km so resistance should generally be negligible.

When people claim that they observe dramatic differences among cables (and they often do so using buzzwords like "sweetness", "focus" and similar BS), if the test is not minimally a blind test then I tend to discount the claims unless they can back it up with some objective data. I mean, in reality, when it comes to subjective judgments, you can pretty much convince yourself of anything.

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.

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.