The cable is very simple: multiple strands of litz wire bound with polypropylene hollow-braid. It’s also very inexpensive provided you can find a source of surplus litz wire. See pictures at:
http://www.audiocircle.com/index.php?action=gallery;area=browse;user=1053Litz wire is just multiple strands of magnet wire rope-lay twisted. There are literally thousands of litz wire configurations ranging from 2/0 to 40awg using magnet wire from 18 to 56awg with dozens of different insulations and geometries. I got a good buy on several thousand feet of 24awg 105/44 SPSD. That means, 24awg overall with 105 strands of 44awg magnet wire, each insulated with a single layer of polyurethane and served with a single layer of Dacron. Understanding litz wire nomenclature is important so you can buy the right stuff. See
www.coonerwire.com,
www.neewc.com, and
www.hmwire.com for more information.
When choosing a litz wire for DIY speaker cables, only two things are important: The film insulation on the magnet wire must be polyurethane or other “solderable” insulation, and there must be an outer fiber insulation of Nylon, Dacron, or other “solderable” material. “Solderable” means the insulation burns/melts away with the heat of molten solder. The 15awg litz wire shown in the gallery is unsuitable, IMO, because: The heavy gauge of the wire and the Nylon film insulation make it difficult to tin without a high temperature solder pot; Without an outer fiber insulation there is risk of chaffing and abrasion leading to shorts in the cable; I don’t like the sound of magnet wire larger than 39-40awg. Note: Litz wire up to about 20awg can be tinned with a soldering iron. Just make sure you apply plenty of heat and fresh solder to insure the insulation gets burned off the inner strands of magnet wire.
For each individual cable I cut the appropriate number of litz wires to the exact length required, +/- .5mm, and tinned each end in a small solder pot. I divided the cut and tinned litz wires into four equal bundles and, with a hot soldering iron, fused the ends of each bundle together making four composite conductors. Two conductors were marked “+” and two marked “-”. I arranged the four conductors in a star-quad and pulled them through a length of hollow-braid, polypropylene rope. The exposed ends of litz wire were protected with heat shrink and the hollow-braid was seized with dental floss tied in a double constrictor knot.
The tricky part is determining how big to make the cable. You could follow the conventional wisdom, or, as I did, just keep increasing the size of each conductor until you don’t hear further improvement or you run out of wire. With my 110dB horns and powered-sub woofers, the conventional wisdom says I should be happy with 15awg speaker cables. That’s where I started. Single-wired with 15awg sounded good but 12awg was better and 9awg was better still. Then I started all over again with penta-wired cables. I finally settled on 15, 12, and 9awg for the tweeter, mid, and low horns, respectively, and 18awg to each powered sub. That totals 6awg.
I can’t tell where to find inexpensive surplus litz wire because that’s the nature of surplus: availability and price are uncertain. I suggest you start with Google and the links above.
