Skin Effect in Speaker Cables - Conclusion
So What Does This All Mean In The Grand Scheme of Things?
We know from our calculations that our total loss in a 10 foot run of 12AWG wire from the DC and AC resistances into a 2 ohm speaker load is -0.18dB at 20 kHz while our actual measured losses were -0.14dB. To get an idea for how insignificant this is in the grand scheme of things, I have included a frequency response plot from one of the industrys best dome tweeters which is known for its excellent dynamics, power handling, and on/off axis frequency response. Pictured below is the on and off axis (30, 60 degrees, respectively) of the Scan Speak 970000 or more popularly referred to by Audiophiles as the "Revelator".
Notice how this tweeter has a relatively flat frequency response to 20kHz, but falls off more than -10dB at 30° off axis at 20kHz, and -15dB at 60° off axis at 20kHz!
In the majority of two channel audio set-up's the listener does not listen to their speakers directly on-axis. Depending on the loudspeaker design, room acoustics, and listening preferences, the user may decide to slightly "toe-in" their speakers. However, even "toe-in" will not account for the majority of these losses. Since we don't listen to music in an Anechoic Chamber, room acoustics alone will further worsen this problem of high frequency attenuation.
Fletcher & Munson Curve (Equal Loudness Contours)
We must also consider a very obvious, but often overlooked limitation to high frequency performance in our audio systems. Our Ears! The majority of adults can rarely hear up to 20kHz and those who are fortunate enough to hear up to 20kHz do so at a much less perceived level as can be seen by the Fletcher Munson curve that illustrates the sensitivty of human hearing related to amplitude and frequency response. Let us also not forget that there is hardly any musical energy that extends nearly up to 20KHz, as it is mostly harmonic in nature with very little applied power and thus resultant SPL at the loudspeaker.
This curve depects human perception of equal loudness vs frequency and amplitude. Notice the curve 50dB @ 1kHz; In order for the human ear to perceive 20kHz at the same loudness, the amplitude needs to be increased by 20dB to a total level of 70B!
So next time someone tries to tell you that their cables will reduce "Skin Effect" and thus will yield better high frequency performance or phase coherence of your system, smirk and ask them how they can reduce high frequency off-axis losses and minimze phase coherence problems of your loudspeakers, room acoustics losses resulting in associated phasing issues, human hearing sensitivity losses at high frequencies, and phase changes due to the changes of air pressure and soundwave propagation in your room?
The bottom line is Skin Effect is not a relevant factor of concern when choosing / designing high performance loudspeaker cables for hifi audio systems. The DC resistance and inductance of the cable are far more important factors as can be seen in our Speaker Cable Face Off and Cross Coax vs Zip Cord articles where we modeled lumped element parameters (R,L,C) of speaker cables.
For more information on skin effect and its impact on cable resistance and inductance, see Calculating Inductance of Speaker Cables.
You should question the validity and intentions of a particular cable vendor(s) when they boast in their marketing literature about solving the "Skin Effect" problem, and ask yourself, "Are they stressing this point as a means to an ends to justify their outlandish asking price of their 'exotic' speaker cables"?
Next we will look at the Fallacy of "Strand Jumping" leading to the myth of diode rectification and how this theory cannot be sound as it violates basic Electrical Engineering Principles, the Laws of Physics, and common sense.
"Switching Power Supply Systems" by Abraham I. Pressman , Second Edition