Back in 1984, when writing for HI FI News, I reported on how to make an inexpensive interconnect from a stock cable supplied by RS components. Of course, such cables include many variations mainly designed for industrial applications. Some of these (perhaps unintendedly or accidentally) have favourable properties for audio interconnection. Indeed some audio cable brands still trawl industrial cable catalogues seeking out those that could be made up and packaged for audio use.
At the time I received correspondence from a Mark Stager of NY, USA who had looked up the US equivalent cable, ordered some, and received something else, an IBM specification #165 7265. He wrote to me wondering whether I had got the type number wrong, but it was not my error. Now, more than 30 years later, Stager has contacted me to explain about his cable making operation that goes back some 20 years and was inspired by my article. He was again using twisted pair technology, and recently offered HIFICRITIC a silver-cored single strand interconnect product for review, drawn from his direct sale Silver Solids operation.
As you might have guessed, it uses single strand wire of 0.020 inch (0.5 mm) diameter, a soft tempered silver of 99.9% purity chosen (in preference to still higher grades of metal purity) for its sound character, particularly when polished after drawing. Cable characteristics comprise a low 35pF/m capacitance, and negligible inductance. The inherent bandwidth will exceed 500MHz, for this Teflon tube dielectric construction with twisted pair geometry. Technically this type is well known to afford a good degree of both radio frequency and hum field shielding, so there is no further shield.
Terminations for the unbalanced version use well-toleranced Canare RCA/phono plugs (inexpensive, well regarded and 75 Ohm matched); Neutrik XLRs are chosen for the three conductor balanced connection version. The solder used for the terminations is Cardas' well regarded 'quad eutectic' formulation. Note that Teflon is microphonic, and with the cable connected open circuit into a high impedance pre-amp input (such as a Townsend Allegri), the cable 'speaks' electrically when tapped, so careful routing is important.
Focus was particularly good, and the midrange colorations sometimes encountered with certain 'over designed' cables was quite absent. Detail retrieval was high, the bass lines were crisp, and this cable sounded quite upbeat with good musical timing, and therefore remained consistently entertaining. My experience with Teflon would suggest that there may be further mild improvement over the next few hundred hours of use. At this stage the sound quality rating is 95 points (note that this is not a percentage rating), which is fine for the price.
It is physically almost vestigial, and not really self-supporting, so do take extra care not to loop or entangle the channels during installation, as this could cause unwanted coupling between the channels. Ideally the length chosen should just right so as to remain in the air and not rest on products or equipment supports. The metal tie twists used with the packing should be discarded, while the polymer locking ties also supplied may be used to keep order and physically pair the two channels, minimizing possible hum induction.