An open format of slides, anecdotes, questions, answers, comments and discussions filled the evening. Steve Lampen amazed everyone with his encyclopedic knowledge of wire and cable, while Kurt Denke, whose Blue Jeans Cable is a good customer of Belden's, related much about the business of selling AV cables without relying on anything other than engineering facts.

Much discussed was the "audiophile" cable and accessories market. Belden makes no claims about unscientific or pseudoscientific characteristics, but rather sticks to the engineering facts about its products. Resellers are free to make their own claims about their sometimes odd use of cable in their products, such as configurations that drastically increase capacitance or resistance. Also discussed were inventive claims and steep prices by some vendors. As Steve said, "Wire and cable are pretty simple and boring." A little inventive marketing is often used, as in selling anything. Beware of clever terms that are trademarked, he said, as usually only the word is trademarked and that has nothing to do with actual engineering achievement.

Virtually all AV cables are made in China today. Blue Jeans Cable is one of the few that sells some cables where the cable is verifiably made in the USA by Belden, but they still need to have assembly and connectorization done in China. It does cost more than the budget, all-Chinese cables they also sell.

The discussions continued with some information on Belden's oxygen content of the copper — you can get 99.95% or 99.995%, which has less than 1% difference in resistance. Cheap copper wire also may not be properly annealed, a heat treatment which puts flexibility into the drawn wire. Gold makes nice wire, but is not a particularly good conductor. Steve related a story about Belden's making fine gold wire for the Manhattan Project in WWII. Because copper and aluminum was in short supply two tons of gold were taken from Ft. Knox and made into wire. After the war it was recycled, and only 2 ounces were gone from the initial 2 tons.

Questions were asked about some characteristics of good audio cable. Kurt said for speakers, you want low resistance, so a fairly big gauge. You can look up your situation in a table. Not too much inductance and capacitance, otherwise that is not too critical. Steve said that normal wire capacitance is not critical for speaker wire customers want less, but any effect depends on source impedance. Inductance is so low, it's not so important in speaker cable, but gauge size is, to a point.

For line-level interconnects — CMMR (common mode rejection ratio), shielding, low capacitance, and impedance consistency is needed in digital cables. Unbalanced analog audio just needs decently low capacitance and shielding. In some cases you don't even need shielding.

Shielding on balanced and unbalanced cables was asked about. Many of Kurt's customers using unbalanced systems get ground loops. Shield coverage percentage, spiral vs. braid, double spirals, French braid, and drain wires were discussed. Foil shields are only effective for very high frequencies, above 10MHz. Braid only goes down to about 1kHz. 60Hz goes through almost anything, so you need a balanced line to reject that. Foil has triboelectric noise when flexed, so foil or foil+braid is not for portable use.

Regarding capacitance, 13pF/ft is the lowest they (Belden) make in twisted pair; 30pF is average, poor cables are like 50pF/ft.

A comment was made that code (NEC) does not allow running any other signals in a conduit with speaker wires, which can have lots of power. Also noted was that Speakon and banana connectors are not UL approved.

Kurt thinks stranding vs solid wire is mostly a flex life issue for speaker wire. Otherwise, it's of no particular importance except to those that believe in unproven skin effects. Solid wire is fine, just not too flexible. Also, crimp terminations are excellent, as are ultrasonically welded terminations.

Steve Lampen told a story about very fine 52 gauge wire at Belden, which is nearly invisible. The woman who ran the machine retired. Belden couldn't find anyone who could run the machine (making wire for space satellites). Now they use a computerized machine for wire down to 60 gauge.

Wire gauges were discussed, which are done by cross sectional area on a log scale. This makes calculations easy.

Steve spoke about the speed of signals in cable, which is related to the plastic insulation around the cable because of magnetic field interaction. A signal is faster with more air in the insulator (a vacuum would be even faster). Fiber optics are actually more like 50% of the speed of light, whereas good copper is more like 85%. Kurt noted that the dielectric foam insulation has many names for marketing purpose. The foam does affects the characteristic impedance and capacitance of a cable, vs. a solid dielectric covering.

Kurt said that his big customers are home theater installers, which seem to appreciate his no-BS sales approach. He wondered originally if such an approach was even viable, but business has been good. Also talked about were legal threats by other cable companies, and the time Kurt, a former attorney, did not back down from such a tactic.