As you can imagine, an unbalanced connection
is likely to suffer from induced noise, and this was why the
balanced input and output was developed. As you will see in Fig
7, the link between two items of gear is now made using 3 connections,
a +ve, -ve and a ground. Only the +ve and -ve connections contribute
to the audio, and the cable screen now simply protects these
two as in Fig 8. For best drainage of induced currents, this
screen connector should be bonded to the chassis of the unit
at each end. The balanced input/output provides further noise
suppression as any induced currents that do get through to the
+ve and -ve connectors can be filtered out as they will be equal
in both wires, whereas the audio signal is +ve in one and -ve
in the other. |