Analogue Input Signal Cables - Yamaha Nexo NXAMP4X4 User Manual

SETTING-UP ADVICE
The immunity (this word describes the ability to cope with electromagnetic disturbance
generated by other items and natural phenomena) requirements that we have considered
exceed those applicable to the "Commercial and light industrial environment" of the
product family EMC standard for immunity. In order to provide a further safety margin, we
recommend that you do not operate the Powered TDcontrollers in the presence of
electromagnetic interference exceeding half of the limits found in this standard.
These two EMC standards are those applicable to pro-audio equipment for the
implementation of the "EMC directive".

Analogue input signal cables

Analogue signals should be connected to the input ports of the NXAMP Powered
TDcontroller via shielded twisted pair or Starquad cable fitted with XLR connectors on the
NXAMP side. We recommend the use of low transfer impedance cables with a braided
shield and transfer impedance below 10 mΩ/m.
The NXAMP Powered TDcontroller is intended to be used with symmetrical (balanced)
sources (for instance a mixer, see figure bellow). You can see that the TDcontroller
provides a low impedance path between pin 1 of its XLR connectors and its chassis. The
TDcontroller can sustain high current in pin 1 without degradation of output noise. We
recommend that the sources and loads you use have the same desirable characteristics.
It is sometimes claimed that connecting cable shield at both ends creates ground loops,
and that the current flowing in such loops will produce noise. This is not the case for most
professional audio equipment. In short, there are two kinds of loops in which voltages are
present: the loops formed by signal wires, and the loops formed by grounded conductors,
among which are protective earth conductors (PE) and signal cable shields.
When a cable shield is grounded at both ends, a loop is closed, and the resulting current
causes a reduction of the voltage induced on signal lines. This effect is what the cable
shield is intended to produce, since this is how it protects your signal from magnetic fields.
If you are using an asymmetrical (unbalanced) source (not recommended), it is best to use
a shielded twisted pair and to connect wire 3 of the cable to the shield at the source output
end (see figure bellow).
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