Reference

Sidebar 1: Test Group

The variety of cables tested alongside the Supra Ply (D) includes examples of generic types that are universally used or accessible (A, B, C) or easily made up (E, F). Other purpose-made audio-grade cables (G–H) were needed to contrast against. They had to be practical and immediately wireable—many audiophile cables are not. In alphabetical order:

A) Zipcord is 0.5mm² Cross-Sectional Area (CSA) (footnote 1), comprising 16 0.2mm (16/0.2) strands of plain copper in an oval sheath. It's commonly used for table lamps as well as connecting budget speakers.

B) Connectronics is this maker's plain, 2.5mm² CSA twin-core cable in a heavy, circular PVC sheath (footnote 2), with about 30 strands. Made for speakers, it is like a 20A-rated AC power cord.

C) Monster Cable is the LF section of the budget bi-wire speaker cable, sold for installation in 1991. The measured conductors comprise at least 100 thin strands of Oxygen Free Copper (OFC) (footnote 3) totaling about 2.5mm² CSA, cased in transparent and soft circular PVC with a black, rippable, circular PVC sheath. The unused HF conductors are thin solid-core, not unlike cable E. They are inside the sheath but were wholly unconnected during tests.

D) Jenving's Supra Ply 2.0 comprises 240 tin-plated strands totaling 2.0mm² CSA that are better than 99.9% OFC, in a rectangular, maximum-capacitance profile. The quite thin, "Ice Blue" colored PVC insulation is stabilized; ie, emission of chloride is low. The overall transparent sheath is ordinary PVC.

E) Twisted 0.5mm² CSA solid-core cable, PVC-insulated with no sheath, and twisted about 1 twist (or turn) per inch. The diameter follows a theoretical optimum for low-dispersion audio transmission developed by Dr. Malcolm Omar Hawksford, as originally published in Hi-Fi News & Record Review in August 1985 and rewritten for Stereophile in Vol.18 No.10, October 1995.

F) Twisted 1mm² CSA cable, comprising 32 strands of plain 0.2mm, PVC-insulated and loosely twisted about half a turn per inch, with no sheath.

G) Sonic Link AST-150. Comprises 30 strands of 0.25mm tinned copper, insulated and sheathed in silicone rubber. Sample was blue. Similar physical characteristics to any arctic-grade two-core, 1.5mm² AC cable; ie, dressability is a notch above common PVC.

H) Sonic Link, three-core "audio-grade" AC cable. The third core was not connected at all. A two-core version is usually available. Each core comprises 19 thick strands of 0.25mm silver-plated copper with PTFE insulation—including a thin but extremely rugged sheath. Doing much stripping would be taxing without special PTFE strippers.—Ben Duncan

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Footnote 1: Wire is usually circular, and a 1mm-diameter circle has a CSA of only 0.79mm². CSA (not the diameter) defines current capacity for a given temperature rise.

Footnote 2: PVC is the common plastic polyvinylchloride. Nobody makes capacitors from PVC because its dielectric losses are so high; ie, it steals energy. Yet all cables are, in part, elongated capacitors. PVC (like most plastics) also emits chemically reactive substances (eg, plasticizers and chloride ions) that can oxidize conductor skins, making them semiconducting and diodic.

Footnote 3: Raw copper contains oxygen and has random crystallinity. Successive annealing and related processes remove impurities, including oxygen. When oxygen levels are below about 1ppm (one part per million), the copper is considered free of oxygen, hence the designation OFC. In reality, at least the surface will eventually re-oxidize. Yet it is reported (at least with silver) that tarnishability ceases when purity exceeds 99.99999%.

Footnote 4: Malcolm Omar Hawksford, "The Essex Echo," Hi-Fi News & Record Review,