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Unbalanced Connections • 31

Version 1.2 July 2010

We’ve told you, both earlier in this manual, and in

Introduction to Livewire; System Design Reference

& Primer, that Axia recommends balanced audio con-

nections when connecting analog source and destina-

tion 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 recom-

mend connecting Axia nodes to unbalanced equipment:

Unbalanced Destinations

To feed audio to an unbalanced destination from the

8x8 Analog node 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 com-

mon (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 lev-

els of +24 dBu.

Generally the unused output pin should not be tied to

the shield. Doing so will not harm the node, however do-

ing so will activate a feature that will increase the output

level by 6 dB, which is generally not desirable.

Feeding unbalanced device inputs from Axia 8x8

analog node outputs.

Unbalanced Sources

To feed an unbalanced signal from a source into the

inputs of the analog 8x8 node 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), as follows.

Axia node’s analog inputs fed from an unbalanced

source where both pieces of equipment are tied to a

facility ground.

Appendix A: Unbalanced Connections