Quote:
Originally Posted by
alan0354
I actually did calculation and posted here, if you read the first link in post# 59 below, I actually calculate the resistance(actually called impedance) due to the inductance at 20KHz, it is 0.22ohm for a 7ft wire. That is a lot of resistance at 20KHz. The resistance of the wire is really not important. ....
Read this, get back to me -
https://www.avsforum.com/forum/89-sp...rspective.html
Quoting myself -
But longer runs come with a second problem I had never calculated before. Using the above analysis, I determined what frequencies would be effected by the
Inductive Impedance of 50ft of very common 13ga/2.5mm² twin lead cable.
At 2.286% Inductive Impedance loss, the frequency was 3,614hz.
That is MUCH lower than I would have imagined.
At 10% Inductive Impedance loss, the frequency was 12,650hz.
Capacitive loses were still well outside the Audio Range. But, again, the
Inductive losses were much more significant than I imagined.
Which results in a combined
Resistive and Inductive loss of about 6% at 3,614hz and about 13% at 12,650hz. In terms of dB of loss, that's still not much, but I don't know anyone who really want to lose 14% of their signal.
And more quoting myself -
Seems pretty extreme, but when you convert Percent of Loss to Perceived Sound Loss (in other words, what you actually hear), it breaks down like this.
dB = 20 log(Vo/Vi)
2.86% Inductive loss at 3,614hz is -0.2009 dB; which is microscopic and insignificant.
10% inductive loss at 12,650hz is -0.91515 dB, which is larger but still insignificant.
However 50ft of 13ga (2.62mm²) wire has a Resistive loss of 0.10015 ohms, or 1.25%. That's not really enough to make a difference in the perceived sound.
2.86% + 1.25% = 4.11% or -0.365 dB; microscopic (3, 614hz)
10% + 1.25% = 11.25% = -1.037 dB; still way too small too matter. (12,650hz)
Except, I am simply not wiling to allow 10% of my signal to be lost and wasted. So, I will choose my wire and wire length accordingly.
Steve/bluewizard