No one actually knows how to lculate what speaker cable they need

Mr. keppertup

Silver has a better conductivity than cooper by 9%. It's cost 94 times more. There is no way you can get a silver wire for $7/feet. Silver's melting point is close to the cooper (about 1,000 deg. C). very hard to work with.

Not the elements inside or other do the difference but the overall resistance.
That could be achieved in other ways too, without using exotic materials.
For the distance, I use two different cables (red and black) that are never in parallel.
All your say is not in line, as I excused non coil speakers from this conversation, and yours are ribbons. (Magnepan MG IIIa’s).

Mr. kosst_amojan
Sorry that all your money could't buy you some knowladge.

Skin effect:

What about the wires inside the speaker boxes or inside the amplifier? They are in that loop of speaker's cables. 

·         Speaker manufacturer provide FR (Frequency Response) data that was measured in test.

·         Amplifier manufacturer provide FR data that was measured in test as well as calculated.

·         The above data is often reviewed and proved by magazines and web sites. They are true.

None takes measurements to tangles the skin effect issue. Speaker cable manufacturer's that never provides any piece of technical data, all the sudden do pay special attention to the skin effect. Why?

The other part is that what the FR of skin effect is telling us, that a 0 awg cable that has a 150A current capacity, is good up to 250Hz@150A. this cable can still pass way more current at 20kHz than a thin cable. A cable of 19 AWG van pass 21kHz @ 1.8A. A 0 awg can do that too!

You say: "Cables are VERY low impedance in the audio spectrum; certainly lower than the output impedance of the vast majority of amps out there". Absolutly incorrect. Most power amplifiers out there are class A/B and have DF of 200 and above. 

Most speaker cables are 12-14 AWG and are 8'-24' long. Your say  VERY low impedance shall get figures. you will find out that the figures are no more that low vs. the output resistance of amplifers, when using 8 ohms / DF.

@b4icu said:

For the 3x0 AWG suggestion: My suggestion was for 3 AWG at 8’.
You require 20’. That increases the cable resistance by 3 and if you go to the guage table it calls for a 3 times 0 AWG to keep it the same as a 3 AWG of 8’ long.
That’s Ohms law.

@b4icu, you are sadly mistaken. This quote demonstrates your ignorance of the electrical “engineering” subject matter that you profess expertise in.

For your information, Ohm’s Law states that resistance (in Ohms) is equal to the potential difference (in Volts) measured across a conductor divided by the current (in Amperes) flowing through it.

Ohms law is saying that too, as any relation between U (voltage), I (current) and R (resistance). U= I x R
This can be also R = U / I or I = U / R. The power P = I x U in AC also x2.
What about the resistance (R) of a cable, if you need to keep it the same, but also to extend that cable from 8' to 20'?
To keep the voltage drop on a resistor (the speaker cable), if you make it longer, you need to increase its cross section to keep it the same R.
this is exactly what 3 AWG at 8’ would become 3x0 AWG at 20'.
Go to the AWG table and do your calc.

Your "Smart" quote from Google is showing how little you understand this subject. Way less than you need for an argue with it.