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Technical and scientific discussion of amps, cables and other topics.

RE: Thanks for the response.

Hi
"I believe the simplest concept of 12 gauge Romex is fantastic in the bass but not further up in frequency."

Here is why. The need for a low resistance source for the woofer was explained already. The current flowing in a speaker cable is automatically balanced, that is two equal but opposite currents.

A magnetic field surrounds a conductor carrying current, that field gives the wire the property of series inductance. If one places two equal but opposite conductors in close proximity, the equal but opposite magnetic fields cancel each other out.
One can see this if you wind a coil of wire and measure it's inductance then close the opening until the two sides are close together and now the inductance is much much lower.

In a speaker cable, the conductors are not infinitely close together in fact in Romex or hardware store extension cord, the conductors are separated for safety by filler and insulation.

As a result of that spacing, there is what is called leakage flux, flux that does not couple or cancel and becomes a series L. As a result, the series inductance per foot can add up if the length is sufficient to roll off the high end. It's parallel C and series L per foot is a good way to look at wire, a short wire is always better than a longer one of the same type.
I have a tower that I measure speakers with in an anechoic condition, I needed to run a 125 foot speaker cable to the tower and needed that cable to have negligible effect (1/10dB or less) on the speakers measurements. I had samples of a number of commercial speaker cables and many types of AC cords and RF cables.
After many measurements with an HP network analyzer, I found that a pair of cross coupled coax cables gave the best practical results. The 125 foot cable had approximately the same series L of the woven Kimber hifi cable (12 feet long) sample while having less Rdc and less C per foot.
Anyway, if you interested in trying what appears to be VERY good electrically speaking, take advantage of true wire science, try some lmr-400 ultra flex at a screaming $1.20 a foot . (I found some at a hamfest)
http://www.universal-radio.com/catalog/cable/coax.html

Coax is an attempt to minimize the series inductance to a minimum value with near perfect field cancellation. Depending on the type, some of it also has very low C per foot, all in all this area (RF) is where the vast majority of cable research has been conducted because all the secondary effects becomes ever larger as one climbs the decade after decade above audio in frequency.
Best,
Tom



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