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In the Forum: Audio Discussions
In the Thread: We who are about to die... (a cable thread)
Post Subject: If not hammers, then glass?Posted by Bud on: 6/30/2008
Hi Paul,
The net gauge for one cable of the 140 strands of #40 stuff is #15 AWG, as far as circular mils of area vs current induced heating goes. The surface area is some 13 times that of a solid #15 gauge copper wire. A minimum of 10 times the surface area of an equivalent solid wire is the Litz standard. There are two or three varieties of Litz lay up though. Also, this is only for insulated strands. Bare wire in this sort of mad plan is not considered Litz by the RF folks, because it does not have the external field isolation that the insulated stuff has.
We buy the wire from a company that used to make wire for magnetic memory and are thus the premier redraw house in the US, though, I suppose there are two others just as good in the rest of the world. They do all of the lay up and present us with the final cable on a spool, ready for use in coil winding for audio transformers, which we do to get to live indoors.
The only feasible way to dress the ends is with a solder pot. Just forget about bare copper here, you cannot mechanically strip this many fine wires and remain sane. Since we are not talking about minimalist energy transfer here, the dissimilar metals question really doesn't raise it's argumentative head. I am sure bare copper to bare copper would be best, but the cupric contamination rate would be phenomenal in such a case and you would end up removing a new length of wire insulation about every six months.
The 2 inch radius is really an infinite one, but 2 inches is about the limit for interference that brings an audible change in a high resolution system, where the information that has been stripped away by poor grounds and sodden transformers/capacitors, has been kept to a minimum.
The Litz immunity to external field events just comes from the intermittant exposure of the individual strands as the outer surface, down the length of the cable, as opposed to the continuous exposure of the surface of a solid cable, or even a typical multi strand cable.
The use of small amounts of low dielectric constant material is allowed beecause you space the peices down the length of the entire cablee and it is just a resevoir to aid the dielectric coating on the wires and that supplied by the cotton sleeve. Using this many, or more, strands of bare copper, even in a pure vihyl or nylon sleeve, is audibly more colored than the Litz in a cotton tube without any extra dielectric added. Bare Litz wire is not audibly different from that in cotton, except in the information content of very wide band, low amplitude signals, like hall echo. Musical instrument sound is equivalent for direct tones and their constituent harmonies.
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