More Information

Materials

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.

Mechanical pair specifications

	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

Electrical pair specifications

	Description	Unit of measurement	Actual result
	Resistance	Ohm/km
	Conductor		93.2
	Shield		23.5
	Insulation	Mohm/km	<1200
	Capacitance	pF/m
	Core to core		50 average
	Core to shield		94.6
	Test voltage	Volt	1000v/min no cracks

Overall jacket properties

	Jacket	Material	Flexible PVC/neoprene composite
		Overall diameter	6.00mm
		Tensile strength	0.85Kg/mm2
		Elongation	>250%
		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
1	Ground	Screen	Screen	Screen	Screen	Screen	Screen
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