AWG is the American measurement unit for cable and equals the approximate cross section of a cable in mm².

The numerical value of this US American system denotes the respective conductor cross-section or rather, the conductor diameter. The numbers themselves are non-dimensional and are derived from a logarithmic relationship to a reference value (similar to the known measurement decibel). Since the calculation specification is rather unwieldy for daily use, a table is used which establishes the interrelationship between the AWG figure and the corresponding cross-section or rather diameter. It should be noted that the effective conductor cross-section is described and so for stranded cable, a space factor is considered which allows the cross-sectional area (wire and air) a size from 25% up to 40%.

Comparison list between AWG and cross-section in mm², whereby the equivalent cross-sectional surface of the AWG figure is up to 10 % above the stated metric comparison surface:

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Bi-wiring is known as the connection between the amplifier and the loudspeaker with respectively two pairs of conductors for the upper and lower frequency range. A loudspeaker which is suitable for bi-wiring has two separate paths for the plus and minus signal. Many loudspeaker manufacturers hold the view that the reproduction of finer details is improved when the paths from the amplifier to the loudspeaker are separately attached. 

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CE

The European Union has enacted comprehensive directives for product safety and environmental compatibility. These regulations are being continually extended and provide, implemented in the respective national legislation, for the safe use of products by the user as well as the proper disposal of equipment after the end of its service life.

A manufacturer confirms that his product, when marked with the CE sign, conforms to the relevant regulations.

IEC
Is the International Electrical Commission. It establishes international standards for electrical and electronic equipment and components. With EU agreement and ultimately national standardisation and legislation, these recommendations become binding.

An example of IEC and CE conformity: Loudspeaker connection terminals on audio equipment and indeed loudspeakers and amplifiers in general must be shock hazard protected, as long as it cannot be ruled out that they produce more than 34.5 volts at the loudspeaker terminals.  As a consequence, WBT offers an ever widening range of fully insulated pole terminals. With the newest product, the nextgen terminal WBT-0710 we have succeeded in concealing the insulation beneath polished metal. In addition, for some time now, loudspeaker plugs may no longer be offered in a ‘plugged-in condition’ with a bare metal conductor area. (See the Safety Pin Banana WBT-0645 and the Sandwich Spades WBT-0680/-0660, whereby the Safety Pin, which may not be permitted in accordance with the ban on standard banana plugs derived from the CE, can be used because of the shock hazard protection).

The fact that loudspeaker amplifier connections must be performed with cables which require a plug or similar connection at both ends continues to be a safety problem, when loudspeaker ratings of more than 150 watt are ‘plugged’.

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Whoever has seen a picture on their television with double outlines (ghosting), or failed to get a connection on their ISDN telephone or data link because of faulty termination impedance, or stood in front of a damaged microwave in which unsuitable crockery has been placed, has been a witness to a mismatch and indeed mismatches from characteristic impedance which is the result of damaging reflections.

It is not only the so called performance matching between an electrical generator and a consumer load, which is necessary to pass on the maximum performance from the source but also the matching of a running interconnection at the source on one side and at the load on the other side which is responsible for the avoidance of temporally reflections. Since it is scarcely possible to match impedance (the name for a general complex resistance) from one end of a circuit to the other, the designated circuit with its characteristic impedance is given the value of the source and load impedance, which is necessary for reflection free, undisturbed signal transmission.

The designation of the characteristic impedance of cable, frequency independent in Ω shows that the model or rather the approximation of a low loss or loss free set-up is the basis. However, it cannot be denied that it is the reactive part of the conductor geometry (inductance and capacitance) which oppose the propagation of current and voltage state (the so called waves) resistance. Their size is intrinsically controlled through the geometry, ohmischer looped resistance and isolation loss and for real audio current generally negligible.

Due to the fact that the geometry of RCA connectors, the bodies of which are conductors, have in their base form a feasible resistance of between 15 Ω and 45 Ω in the best case, must the full metal form be designed as a bifilar arrangement, in consideration of the geometric dimensions, so that, with a 75 Ω characteristic impedance, a reflection free operation with a suitable cable can be made.

Characteristic Impedance
Surge Impedance

Any signal path should be configured in that way, that source ↔ connection elements ↔ transmission line connection elements ↔ load all have identical (characteristic) impedance (i.e. the commonly complex form of a general resistance). The small signal connections of audio devices for instance are obviously suited for engaged steps in this direction. Such steps are supported by the established technology of broad band transmission and measurement. They offer well proved connection and transmission elements with defined characteristic impedance values (50 Ω, 75 Ω, ., ... )

Fig.1: Phenomenology of transmission line

The characteristic impedance of an electrical topology – in our case that of a line element – will be evaluated numerically in 'Ohm' like any other resistance, regardless whether it is purely resistive, reactive, or complex, but that is the only property it has common with the evaluation of discrete electrical components. In all cases of discussing electrical arrangements where the propagation velocity of voltage and current states within the topology is of importance the phenomena of wave propagation have to be considered. This requirement applies for power lines, data highways, microstrip devices, etc. and of course hifi connections. There are two principally different ways to become familiar with the understanding of the time and space depending properties of wave propagation on transmission lines. One approach is offered by the network theory by modelling the line by elements derived from the discrete passive elements R, L, and C. But for our purposes another way, the physically based phenomenological approach will better meet our simpler requirements. Look at Fig.1:

When connecting a voltage Ua to the input a-a' of a line (coax, twisted pair …) then a current Ia(t=0) will flow into this port. This current will not depend on the condition defined at the port e-e', it may be short circuit, open-circuit or terminated any way. Only after a certain time tl (1 to 2 ns for 30 cm connection length for instance) the input state reaches the port e-e' (lossless line assumed). If this port is connected to an impedance Ze=Ua/Ia everything is in order. The current Ia may go out as Ie and the voltage Ua may go on to feed Ia into the input. For all other cases, short circuit, open-circuit or line terminated with an impedance Ze ≠ Ua/Ia, at e-e' a correcting state will be generated which corresponds to conditions at e-e'. I.e. for instance that at an open circuit end will generate a state –Ia into direction a-a' because at an open circuit the current has to be zero. This correction state arrives after a time tl at a-a' and superposes the current Ia(2 tl ) going in there at this time.

The resistance – commonly impedance - a line opposes states streaming in or surging in is called surge impedance or characteristic impedance (derived from network theory). The phenomenological point of view gives an evident insight to our main problem discussed here: the insertion of plug connections into a transmission line. As result we can state that we have to avoid any mismatch (Zplug ≠ Zline ) of impedances within the chain defined in the first sentence of this section. As shown any mismatch will generate multiple reflections at all points of impedance imparity and cause measurable and hardly measurable but audible distortions. The best way to achieve the necessary impedance matching for a sufficient frequency range is to aim at broadly used impedances (e. g. 75 Ω).

The specification of cable impedances, frequency independent in Ω, suggests that the base generally used is the lossless or low loss approach.

It is not only the so called power matching between an electrical generator and its load, which is necessary to get the maximum power from the source, but also the matching of a time consuming transmission line to the source at one end and to the load at the other end, which is responsible for the avoidance of temporally resoluted reflections.

Since it is scarcely possible to match a transmission line to different impedances (the name for a complex resistance) at each of its ends, the characteristic impedance of the used transmission line will define the source impedance as well as the load impedance to obtain the desired reflection free and undisturbed signal transmission.
The designation of the characteristic impedance of a cable, frequency independent in Ω shows that the model respectively the underlying approximation commonly used is that of a low loss or lossless device. Nevertheless it should not be forgotten that the reactive parts defined by the line or connector geometry (inductance and capacitance) oppose the propagation of current and voltage states (the so called wave) resistance. Their size is intrinsically controlled through the geometry. Loop resistance and isolation loss are, for audio lines, generally negligible.

Due to the fact that the given geometry of a RCA connection - which is an essential part of the transmission device discussed here - in its basic form allows characteristic impedances between 15 Ω and 45 Ω the full metal form had to be rearranged as a bifilar design in order to achieve reflection free operation in widely used 75 Ω surroundings.

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The crimp connection technique was developed for the use of screwed connections with stranded cable. Stranded cable is cable which has its conductor made from a large number of thin wires which have been twisted together rather than cable with one single thick wire. These thin wires can easily break-off with a screw connection. In addition, they can evade the screw. A reliable and stable connection is therefore not possible.

During crimping, a cable end sleeve is inserted over the end of the stripped stranded cable. The sleeve is then pressed together with crimping pliers. The material then ‘flows’ together as a result of the forming pressure of the pliers creating a homogenous copper rod.

This connection can now be either screwed in to a crimp plug with a grub screw or fixed in a terminal.

In addition to standard cable end sleeves, WBT also offers sleeves with injection moulded plastic collars. When using this version, the sleeve is pushed further over the stripped area so that the collar reaches over the cable insulation. This way, the kink sensitive area between the cable sleeve and cable insulation is protected during bending. This is particularly important if the cable is to be frequently moved.

Crimping is a far superior connection technique for stranded cable in comparison to soldering when cable with a thick cross-section should be soldered, since the possibility of a so called ‘cold’ soldered joint exists. In such a case, an air bubble can form under the cold solder which keeps the joint chemically active and susceptible to surface corrosion.

The deciding advantage of crimping is also that neither soldering material (flux and solder), nor heat are required. Solder is a mixture from, among others, tin, flux (mostly aggressive) and a small part of silver. The solder joint is therefore always seen as the weak point of conductor contact. Heat affects not only the conductor and insulation material but it is also capable of releasing gases from the PVC of the cable sheath which can form on the contact point and remain chemically active. Crimping on the other hand has none of these disturbing characteristics. The cable end sleeves from WBT are available in pure copper (Cu) or fine silver (Ag) and have no negative effects on the conductivity of the cable. In addition, the fixing by means of the grub screw, provides an excellent mechanical stability and keeps the transition resistances to a minimum.

Crimp connectors usually require more fabrication complexity. At WBT all crimp connectors possess Torx screws with a special fine thread. This guarantees that a one time applied pressure will be perfectly held. Crimp connectors are re-useable.

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When two electrical conductors are mechanically joined, an electrical resistance forms between the two conductors. This resistance depends on several factors, among them, from the mechanical force with which the two conductors are pressed together. The greater is the force, the smaller the resistance.

If the contact point vibrates or resonates, this force can change considerably in frequency with the vibration so that the signal is transmitted better or worse in this rhythm. This effect occurs most often with loudspeakers and can be clearly heard as a distortion to the signal.

Manufacturers of loudspeakers have made considerable efforts to construct their chassis’ to be as passive as possible. Nevertheless, vibrations cannot be completely eliminated and these transmit themselves to the binding posts.

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The double Step washers supplied with WBT pole terminals and RCA sockets are inserted between the terminal or socket body and the mounting plate or cabinet wall. They have several functions:

>> They insulate the connection terminal from the respective mounting plate.
>> They ensure that the terminal will not twist when tightening the counter nut.
>> They provide pole identification because they are colour coded.

When installing the pole terminals, the turns should be made in 45° steps. In this way, the entry point for the connection cable on fully insulated pole terminals can be aligned so that the cabling can be comfortably achieved even in narrow spaces.

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(with WBT cable shoes, WBT Power Bridges and the nextgen Pole terminal WBT-0710)

The Elastomer vibration damper consists of a durable, elastic damping rubber. The metal pieces of the contact fork in the WBT cable shoes (and also the contact forks in the WBT Power Bridges) have a cupped form, thanks to their ridges edges, in which Elastomer is inlaid. In this way, resultant vibrations are damped and contact microphonics is eliminated.

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This class of material (essentially represented by Ni, Fe, Co) is marked by its relative Permeability µr, which is intrinsically greater than 1.

The permeability determines the connection between magnetisation H and induction B according to the relationship B=µ0•µr•H her. µr is indeed a material constant but generally, especially with ferromagnetic material, unfortunately not a constant. On the basis of the physical causes of the high permeability, µr is associated for transmission with two extremely unpleasant properties, namely saturation flux density and hysteresis.
 
The first property means that after exceeding a certain magnitude of magnetisation or of the causative current, µr assumes the value of 1 fairly abruptly and with that, nonlinearity similar to that shown by a diode. The second one means that the induction depends not only on the instantaneous value of the current but also on its direction (increasing or decreasing) and so ‘induces’ a further non controllable nonlinearity in each of B’s or rather H’s influenced signal paths.

The influence occurs over the magnetic alternating field of the signal flow, which induces in the conducting materials in its range voltages or rather currents and leads to frequency dependant (linear distortion) eddy current losses. If these losses are caused in ferromagnetic materials, the above mentioned nonlinear distortions become part of the signal.

The only possibility to control these nonlinearities is not to allow them to occur in the first place. For reason of construction, it is not possible to entirely avoid eddy current influences however the use of ferromagnetic material can be avoided.

A magnetisable metal is, for example Nickel. Gold plated surfaces are usually applied on top of a nickel layer since it acts as a primed surface between the metal body and the gold plating.

In order to prevent the above mentioned distortions, WBT uses a complex nickel free gold plating for its top quality products.

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Used in English-speaking areas.
1 Inch = 2,54 cm

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The effect of a body changing its dimensions while applying a magnetic field or changing its state of magnetization is called magnetostriction. The basis for this mechanical deformation is the interaction between the external magnetic field and the elementary magnets formed by the atoms circled by electrons. The evidence of this effect depends on the crystalline structure of the material and the elements containing. The effect is mainly marked in ferromagnetic materials. Concerning an electrical contact, the quality of which is mainly achieved by contact pressure, magnetostrictively caused, as result of the alternating magnetic field of the current of a loudspeaker for instance, changes of geometry would directly modulate the transmitted signal by the alternating transition resistance.

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(Original Equipment Manufacturer)

An OEM is a manufacturer of finished components or products.

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(Oxygen Free Copper)

A special pure copper which contains no oxygen, which can under certain circumstances, create nonlinearity through the formation of CuO on the grain boundary.

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(only with WBT-0234 and WBT-0274)

Makes a mechanical and electrical mounting directly onto the circuit board possible. A cable connection between the socket and board is not required.

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Connectors in consumer electronics equipment are colour coded according to a uniform standard. This allows for a simple connection of the individual equipment and prevents mistakes with cabling.

All WBT cable connectors are available for use with the typical pole identification.

nextgen coaxial plugs and sockets are available with all the pole identification listed in the table below:

Overview of the most important pole identifications

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Cable shoes in which the contact fork has been formed into a closed ring.

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(only possible with the WBT-0645)

When the possibility exists to install bi-wiring connections on one equipment side but not on the other (for example, with a amplifier), then the WBT-0645 allows the possibility to interconnect the two plus contacts (red) or two minus contacts (white) on that piece of equipment. Simply insert the second connector into the back of the spindle of the first and tighten firmly.

Tip: before inserting and/or removing the plug, remember to loosen the central pin/spindle.

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(only with WBT-0645)

The banana plug WBT-0645 is the only banana plug which is equipped with a safety spike (safely pin). This makes the WBT-0645 a CE compliant connection plug according to intention since it prevents the accidental insertion of the plug into a power socket by, for example children playing.

The safety pin is a pure safety spike and has absolutely sonic properties. It should not be confused with the Safety Stick!

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A connection made between two electrical conductors by soldering. A suitable soldering tool and solder will be required.

An important quality criteria for solder is the melting point. Electronic components are often sensitive to heat or embedded in plastic which can become soft on heating. In order to avoid damage under these conditions, the melting point of the solder should be as low as possible. The soldering tool should also not become too hot.

A further quality criteria is the flux which is necessary to minimise the surface tension of the fluid solder so that a wetting of the area to be soldered can take place. Care should be taken to prevent the flux from attacking the area to be soldered.

WBT solder is optimised for both criteria. It has a very low melting point and the flux is halogen free thereby avoiding any corrosion of the sensitive surface.

When the soldering process is considered, the fairly simple procedure of joining two metal pieces together with a third fluid one (molten solder) is in fact very complicated.

It is not enough to bring the molten solder, the flux and the contact pieces to be soldered simply together. The following important parameters should be observed:

• The process of melting and solidifying should ideally take place within narrow temperature ranges so that a quick wetting and also a quick and brittle free solidifying is achieved. Only then will the surface of the solder joint remain smooth and corrosion protected. ´
• The molten solder should not be excessively applied to either the older tip or the copper conductor to be soldered (Of particular importance for equipment manufacturers: the solder must be suited to the valid requirements and the subsequently pre-tin-plated components). 
• The conductivity of the solder materials should not make the completed connection electrically poorer than that of the feed cables.

That today’s good quality solder contains a certain amount of silver is mainly due to the above mentioned requirements. WBT silver solder always contains 4% fine silver. Should the silver content be raised substantially above 4%, the metallurgical balance of the solder would be significantly destroyed and the price disproportionately increased.

The new lead-free WBT solder WBT-0805, WBT-0825 and WBT-0845 possesses a lower increase in conductivity in comparison to the lead containing versions, WBT-0800, WBT-0820 and WBT-0840. This is mainly due to the increased tin content.

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Torque is the product of force and leverage with which, for example, a screw is turned. The unit of measurement is newton meters (Nm). Nm = kgm²/s².

The WBT-0481 torque controlled Dynakey is set to 5 dNm torque (d stands for deci or 1/10th of the value) so that a screw with this screwdriver can only be screwed on with this force (this torque). Thereby, an over screwing of the screw and any accompanying damage to the cable connector will be avoided (see also transition resistance).

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Torx is as a tool fitting, a further development of the hexagonal socket and crosshead screw. The profile is similar to a star with six spikes and rounded tips and edges. The profile is vertical and so no back thrust arises which can lead to damage of the screw head.

WBT uses only screws with T.6 profile, so that only one tool is required for all Torx screws.

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When two electrical conductors are connected, an electrical resistance forms at the transition point between the two conductors. This resistance depends on the contact size and state of the surface. Since surfaces are never flat in microscopic measure, contact only takes place at the highest point.

If one considers that the contact point is made by conductor metal on conductor metal, it is valid, as for all resistance, that the value is determined by specific resistance, the surface through which the current rate flows and the height of the ‘contact peaks’’.

The greater the amount of contact point surfaces there are, the lower the resulting resistance and consequently the greater is the capacity which the contact points can transmit. The conductors must be firmly pressed together so that the distance, the height of the ‘contact peaks’ is as small as possible and the contact area as large as possible.

The greater the force at the contact points, assuming stability, the better the contact. For this reason, all WBT plugs, pole terminals and cable shoes are constructed to either withstand or create high contact force.

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(only with WBT cable shoes and banana plug WBT-0645)

The crimp cages of these cable connectors are equipped with two consecutively placed Torx screws so that the connection can be doubly screwed. The result is a very tight and electrically secure connection with a low transition resistance.

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