Connections, wires and connectors - Electric connections

These consist in two conductors: one which transports the signal, the other which undertakes the mass-function. The mass conductor is used as a screen against electro-static interferences. It in fact gets wrapped around the cable which transports the signal, bringing about what is called Faraday's Cage ^{[8 ]}

The following diagram shows an unbalanced wire connected to a two-pole 1/4" jack connector:

Unbalanced connection

We can see how the wire transporting the signal is connected to the tip of the jack.

If we were to invert the connections at the tip and ring we’d get a phase-inverter wire.

These consist in three conductors: the wire transporting the signal, the mass, and another wire that transports a copy of the signal which has been inverted in phase in relation to the mass. The following diagram will help us to understand this connections scheme:

Signals on a balanced connection

For a more detailed description, read the chapter which deals with the topic of noise, in particular the section dedicated to noise-reduction techniques [Noise reduction ] .

The following diagram shows the connections of a balanced wire with a three-pole 1/4" jack connector:

Connector for balanced connection

In this section's introduction we saw how every wire introduces some distortion which meant an attenuation in the signal passing through it. This is true for any kind of wire, be it optical or electrical.

A typical type of distortion of the electrical connections is the kind defined microphonic distortion. To better illustrate it we need to show a cable, which for simplicity's sake shall be unbalanced, as shown in the following diagram:

Electrical representation of microphonic distortion

In the diagram, we have the two conductors. As already mentioned, a conductor introduces a resistance, which we have represented with the resistances R₁ and R₂. Moreover, electrical charges pass through the two conductors and this can be likened to the behaviour of a condenser. The derived equivalent circuit is that of a pass band filter [Filters ] and this means that the wire in question behaves just like a filter. As the resistance-values at R₁ and R₂ increase, so does the incidence of the filter on the signal. A second problem arising from the presence of an inducted capacity, is that if the two conductors are moved one in relation to the other (for example, when the wire gets bent), the distance between the two plates (to be more precise, between the two conductors) varies by changing the value from the capacity. This means the passage of a current within the condenser which will be audible in the form of a sound. For more in-depth information regarding the causes of noise in electric wires, read the topic-section on noise [Noise ] .