Axia xSelector, Installation & User Manual

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Appendix B:
Unbalanced Connections
We’ve told you, both earlier in this manual, and in the Introduction to Livewire: System Design Reference &
Primer , that Axia recommends balanced audio connections when connecting analog source and destination gear
to the inputs and outputs, respectively, of Axia nodes. Not only do we recommend this for the usual reasons, but
because inter-channel crosstalk between the left and right channels of unbalanced signals sharing the same CAT-5
cable is a possibility. As we’ve mentioned before, we recommend converting between balanced and unbalanced at
the unbalanced device and then using the standard CAT-5 connection from there to the Axia node.
There are a number of active balanced-to-unbalanced and unbalanced-to-balanced adaptors commercially
available at a reasonable cost (see www.studiohub.com for a pair of units that will easily plug and play with our
gear). We’ll suggest one more time that this approach is the way to go, and that using unbalanced cable runs will
compromise the performance of your state of the art Axia audio network. However, if you are in a bind, or otherwise
determined to do so, here is how we recommend connecting Axia nodes to unbalanced equipment:
Unbalanced Destinations
To feed audio to an unbalanced destination from the analog output of an xSelector you must use a separate cable for
the left and right signals, and you will need a shielded RJ-45 plug so you can terminate the shield of the audio cables.
RJ-45 Pin 1 will feed the Left signal with the signal common (e.g. cable shield) connected to the RJ-45 shield. Pin
3 will feed the Right signal with the signal common (e.g. cable shield) connected to the RJ-45 shield. An external pad
may be required if the destination equipment’s inputs cannot accept signals with peak levels of +24 dBu.
Generally the unused output pin should not be tied to the shield. Doing so will not harm the xSelector, however
doing so will activate a feature that will increase the output level by 6 dB, which is generally not desirable.
Unbalanced Sources
To feed an unbalanced signal from a source into the analog inputs of the xSelector, you must use a separate cable
for the left and right signals. We generally prefer the method where the unbalanced signal is presented across the
differential balanced inputs of the node. The handling of the shield will depend on the equipment and grounding
practices used.
If both pieces of equipment are grounded to a facility grounding system then the shield may be left open at one
end (or both ends).