JNeutron, thanks for your obviously very knowledgeable inputs. Yes, there are clearly a number of oversimplifications and "inaccuracies" (which I prefer to think of as "rough order of magnitude approximations") in what has been said in this thread. However, I would question whether or not the "inaccuracies" are relevant to the underlying points that have been made.
For example, concerning your point about propagation delays I am aware that delays at deep bass frequencies can be far longer than the 1.6 ns/ft ballpark figure cited by the OP. At 20 Hz, for instance, I have seen data indicating that for many cable types delays may be 50 times or more greater than that figure. However, that would still equate to more than 2000 miles per second, which clearly corresponds to a negligible amount of time in the context of speaker cables in a home audio system.
Based on the following comment you made in this 2005 thread, it appears that you would agree with that:
Finally, a question I ask out of sincere curiosity: Do you design or manufacture audio cables, and if so, which ones?
Regards,
-- Al
For example, concerning your point about propagation delays I am aware that delays at deep bass frequencies can be far longer than the 1.6 ns/ft ballpark figure cited by the OP. At 20 Hz, for instance, I have seen data indicating that for many cable types delays may be 50 times or more greater than that figure. However, that would still equate to more than 2000 miles per second, which clearly corresponds to a negligible amount of time in the context of speaker cables in a home audio system.
Based on the following comment you made in this 2005 thread, it appears that you would agree with that:
I do agree that the term "prop speed" is rather confusing, as most seem to think it means that the transit time from the amp to the load is of any consideration...IT ISN'T [emphasis added]. But, the term prop speed is directly related to the DC [dielectric constant], L[inductance], and C[capacitance].I certainly don't disagree with that statement, and I doubt that the OP or most of the others who have responded above would disagree. Nor, I suspect, would they disagree with the following statement you made:
But honestly, it's all in the R, L, C, and Q of the cable. Unfortunately, there's been so much mis-information spread around that high end audio guys end up guessing and trial and error, without much in the way of science..and, realistic measurement of matched Z cables is impossible for most wire vendors, as inductance measurements at the tens of nanohenry level are very difficult to do correctly.Regarding your points about skin effect, can you provide us with a QUANTITATIVE feel for the degree to which the result provided by an exponential approximation would deviate from the Bessel function result? For example, what would be the difference between the 63% skin depths at 20 kHz for solid core copper wire as calculated based on the two functions?
Finally, a question I ask out of sincere curiosity: Do you design or manufacture audio cables, and if so, which ones?
Regards,
-- Al