This cable now uses a mixture of Ultra Pure Silver Plated Oxygen Free Copper and Ultra Pure Oxygen Free Copper for its conductors. As with the ultra pure oxygen free copper used in other Van Damme Cables ‘solderability’ and conductivity are much improved. The additional advantage of UPSPOFC is that silver is approximately 5% less resistive than copper. High frequencies, which gravitate to the outside of the conductor due to the skin effect, are conducted slightly more efficiently than the lower frequencies which tend to saturate the UPOFC conductor. In addition silver is less susceptible to corrosion than copper and so the plating offers a protective barrier between the conductor and the insulation or free air.
Cross-linked polyethylene (XLPE) is used for the conductor insulation. Although considerably more expensive than conventional polyethylene it offers distinct advantages over other insulation materials. XLPE has a low dielectric constant (2.2 at 1KHz), essential for minimising high frequency signal losses, and is stable at high temperatures. This temperature stability ensures that the insulation material resists shrink back during the soldering process. It has good abrasion and stress-cracking resistance yet remains flexible down to - 40 degrees C. XLPE also is less environmentally damaging than other insulation materials as it releases carbon dioxide and water during combustion with no halogen emission. The term starquad refers to the construction method used for this type of cable.
Four insulated conductors are tightly twisted together with natural textile fillers and overlaid with an anti-static paper separator. The overall braided screen uses 128 strands of 0.10mm tinned copper giving 98% coverage and unsurpassed screening and mechanical strength. The overall jacket is anti abrasion PVC/neoprene composite which is tough yet flexible even in sub zero temperatures. The four inner conductors of this cable are colour coded white (2) and blue (2). To maximise the cable’s resistance to interference the 2 white conductors should both be connected to the hot (+ve) signal and the 2 blue conductors should both be connected to the cold (-ve) signal.
|Conductor||Material||Bare silver plated ultra pure free copper wire|
|Stranding||7 x 0.08mm|
|Material||Bare ultra pure oxygen free copper wire|
|Stranding||32 x 0.08mm|
|Insulation||Material||Cross linked polyethylene (XLPE)|
|Diameter||1.35mm ± 0.10|
|Colour coding||2 x white 2 x blue|
|Screen||Type||128 x 0.10mm braided tinned oxygen free copper wire|
|98% optical coverage|
|Description||Unit of measurement||Actual result|
|Core to core||50 average|
|Core to shield||94.6|
|Test voltage||Volt||1000v/min no cracks|
|Jacket||Material||Flexible PVC/neoprene composite|
|Heat shock||120 °Cx h no cracks|
|Temp Range||-10 to +60 degrees C|
|Cable||Cable Weight kg/km||65kg|
Star Quad is a type of cable construction used to minimise interference with Balanced Lines. This includes interference both to and from external sources, and interference between adjacent circuits within the quad.
A star quad cable consists of 4 cores tightly twisted together. Both single and multiple quads exist and they commonly have an overall screen.
A single circuit uses opposite cores of the quad, connected in parallel, to form a single balanced pair. The quad arrangement gives a magnetically coaxial structure and the compact, short lay-length allows any induced interference to be more accurately cancelled at a differential input. The cable inductance is also halved and this tends to extend the HF limit in low impedance circuits such as microphone runs. Improvements in interference reduction of the order of 20 dB are often found compared to a standard twisted pair.
It is important that opposing cores are used to make each leg of the balanced pair otherwise the interference rejection will be compromised.
|The correct cores to use can be determined by examination of the cable. The red cores should make one leg and the black cores, the other.|
Manufacturers are not consistent about their colours for the cores. The following is a guide for some popular cable suppliers but it is best to identify the cores independently.
|XLR Pin||Function||BBC||Van Damme||Canare||Gotham||Belden||Mogami|
|2||High||Red + Blue||White + White||White + White||Red + Pink||White + White/Blue||Red + Blue|
|3||Low||Green + White||Blue + Blue||Blue + Blue||White + Ivory or Yellow||Blue + Blue/White||Black + Clear|