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In practice property changes due to wear and tear, e.g. bending of the cable, play a decisive role. Foil and spiral wound screens of lower quality often dislocate in a way that the cores are completely open to distortion. The screening is lessened then. On the other hand, in many applications a high flexibility has to be achieved. In these cases mostly a spiral wound screen is used. Braided screens, due to their better mechanical and tensile strength, are used as overall screens for multicore cables.

The screen of multicores is often tinned which makes further processing considerably easier. Furthermore, we distinguish between separately screened pairs (single screen) and overall screened (overall screen) cables.

So, generally true for delicate applications:
double screening is safer than single screening.

Thanks to the additional jacketing of the cores of microphone cables with conductive plastic, their microphony behaviour can almost be completely reduced. Therefore noise due to bending and moving of the cable can be eliminated.

The insulation provides the galvanic separation of the cores with different potentials against each other as well as against other conductive components (e.g. shielding) and ground. Commonly used insulation materials are PVC and PE, whereas PE allows lower and therefore better capacitive values. This is especially audible at longer runs, where the cable starts to cut treble. In such applications PE ought to be used. When processing the cables with soldering irons or soldering baths the temperature stability of the insulation is important. You can often find thermic instabilities caused by shrinking core insulation.

In data cables the intensity of the inducted signal decreases continuously over the cable length. The logarithmic proportion of transmitter- to receiver level is defined as attenuation.

The measure is decibel (dB).
It is common that the attenuation, which is especially important for multicore cables and which grows linearly with the cable length, is stated for a length of 100 m.
In audio range, losses in a copper conductor contribute to the attenuation.

The braided screen consists of copper wires, often the same the strands are made of. They usually cover the cores and cords in a cross parallel way. The coverage is approximately 85%, the flexibility is sufficient. The mechanical stability is better than with a spiral wound screen.

 the foil screen achieves a coverage of 100%. Its flexibility, though, is not as good as the one of braided and spiral wound screen cables. The foil consists of thin layers of aluminium. Therefore the conductivity is much lower than with copper strands.

The inductance of a conductor circuit, stated in Henry (H), depends basically on the distance between both conductors: the larger the distance, the larger the inductance!
As the cores in audio cables are in close proximity, the inductance is very small and therefore insignificant.

The main and most important element is the inner core. Here you have to distinguish between massive cores and strands. Massive cores use one massive wire as a conductor, whereas the stranded version of the conductor consists of several thin strands and achieves a higher flexibility. 
In general: the thinner the strands are the more flexible the cable will be. Flexibility is most important in mobile use of microphone-, instrument-, loudspeaker- and multicore cables. Besides that, you have to pay special attention to the conductor cross section in case of long cable runs.

The common rule is: The bigger the conductor cross section, the lower the conductor resistance and the better the transmission. This is of utmost importance in the microphone cable field and so cross sections of 0.20 mm² or even better 0.22 mm² are common. For long distances we even recommend 0.50 mm². The alternative to the common copper conductors is the use of oxygen free copper (OFC) which to some extent offers better electrical properties. These values have to be evaluated as the case arises and the usage has to be decided on accordingly. When using loudspeaker cables, special attention has to be given to the conductor cross section due to modern power amplifiers which generate power of 2,000 Watts at 8 ohms respectively 4,000 Watts at 4 ohms in the bass range. Here, maximum values of 180 volts at 40 amperes are reached, which have to be transmitted by the loudspeaker cables. Conductor cross sections which are too small lead to considerable loss of power and in the end possibly to cable failures. Where speakers are concerned, cables with two, four and eight poles in the range of 1.5 mm² to 8 mm² are available according to the system specifications.

The insulating resistance indicates the electrical loss of the conductor.
You can easily imagine these losses as leakage current which flows to the ground via the conductor insulation. The resistance the insulation current has to overcome on the way through the insulator, is the insulating resistance. It should be as high as possible.
The length of a conductor affects the conductor and insulation resistance in different ways: when the conductor resistance grows with the increasing length of a core, the insulating resistance abates at the same ratio.

The capacity of a conductor circuit, stated in Farad (F), depends on the distance between the conductors and on the dielectric coefficient of the insulating material: the smaller the distance between the conductors, the higher the capacity. The usual small distance between the wires usually generates relatively high values of capacitance (130pF), that can be affected by the appropriate selection of the insulation material (for example PE), so that capacities below 70 pF can be achieved. As these capacities result in a low-pass filter reaction of the cable, attenuating highs with large transmission paths, sensitive applications, like transformer balanced and high resistance tube microphones or tube preamplifiers and power amps can be affected. Therefore, this effect has to be considered carefully.

It is worthwhile listening exactly!

This is the DC resistance of the conductor, which depends on the resistance of the conductor material.

It is stated in ohms.
During the transmission of AC with expanding frequency the current does not evenly spread over the conductor area. At high frequencies the current transmission is finally effected only on the conductor surface (skin effect). This can be important for digital data communication; it is insignificant in the range of low-frequency audio uses! The conductor resistance for microphone- and multicore cables should be below 100 ohms/km and for loudspeaker cables below 10 ohms/km.

In practice the cable jacket is strained considerably. It has to withstand mechanical influences, temperature changes, acids, oils and also natural aging. Widely spread is the use of PVC as jacket material, however, lately other new materials with specific qualities have become available.

Crosstalk characterises the unwanted passing of signal energy in close-by circuit lines. Causes are capacitive and inductive couplings as well as marginal leak loss. Stated is the logarithmic proportion of signal power in the sending pair of cores to the incoming power in the defective pair of cores. The measure is decibel (dB), the numerical value should be as high as possible. By twisting close-by pairs with different lengths of twists and by screening activities crosstalk can be minimized.

A cable should have a balanced design, that means with twisted pairs, to guarantee an undisturbed transmission over a long distance. The audio signal will be transmitted in-phase opposite to both inner cores. The interferences, which are not kept out by the screen, show equiphase behaviour and cancel each other out on transformer- and electrically- balanced inputs. This allows – with transformer-balanced inputs- an ungrounded connection between electronic equipment without the dreaded ground loop.

The unbalanced, coaxial wiring uses the screening of the cable as a signal carrying element and is not capable to compensate for interferences.

As regards multicore constructions, the twisting of the single components plays a decisive role, because of the eventuality of a restraining, which can influence mechanical as well as electrical properties considerably .
The cross-talk behaviour can be minimized by the length of the twist (that‘s the length up to the 360 degree rotation of the components). Ribbons or foils of synthetics, respectively fleece, connect a cable lay and avoid that the jacket material will get into the hollow space during the extrusion. That could enormously complicate the stripping or even make it impossible. It also allows the switching of the single elements, thus also improving the flexibility of the cable.

The characteristic impedance in cable technology is defined as input impedance of a homogeneous conductor with endless length.

The measure is Ohm.
The frequency-dependent progression of the characteristic impedance enables statements about incoming signal distortion at imperfections. Frequently the impedance is named as characteristic impedance. The characteristic impedance is constructively forced by the sizes of the inner conductors, the dielectric and the screening. It does not depend on the cable length. The characteristic impedance is insignificant in low-frequency audio applications, but important with high-frequency uses like digital transmission and converting (for example the AES/EBU standard: 110 ohms). There you have to make sure that the characteristic impedance allowances are at +/- 20% of a maximum according to standard, otherwise reflections could distort the signal and especially the signal edge (jitter), thus virtually preventing authentic interpretation. “State-of-the-art” cables offer impedance tolerances of +/- 10% at 3 and 6 MHz.

In a spiral wound screen, the single wires are wound in one direction e.g. without crossings, around the cores. The coverage is 90% to 95% thus achieving higher values than with the braided screen. The flexibility is very good. Both types provide a high screening effect against electro magnetic distortion in the low and high frequency ranges.