AMX NXD-700Vi manual Wiring the NXA-AVB/ETHERNET for Unbalanced Audio

NXA-AVB/ETHERNET Breakout Box

Wiring the NXA-AVB/ETHERNET for Unbalanced Audio

Most domestic audio equipment has unbalanced audio inputs and outputs. This means that the audio output (left, right, or mono) appears on a single wire, and is referenced to "0 V" or "Ground". Typical connectors used are RCA "phono" connectors, DIN plugs/sockets, and 0.25" (6.3mm) or 3.5mm jack plugs/sockets.

Unbalanced audio is adequate for most domestic environments and for line-level signals in a typical broadcast studio. Problems may occur if the signals are carried over long distances, especially if the source and destination have separate main supplies. Use the following wiring drawing (FIG. 8) to configure an unbalanced audio connection.

GND

IN-

IN+

GND

IN-

IN+

AUDIO IN

MIC OUT

GND

OUT-

OUT+

Left Channel	Unbalanced IN
	(Jumper IN- to GND)
Right Channel	Unbalanced IN
	(Jumper IN- to GND)

Microphone Unbalanced OUT

FIG. 8 Wiring the rear AUDIO IN and MIC OUT for use with Unbalanced Audio

When using unbalanced audio for the AUDIO IN connector (FIG. 8), the "-" and the "GND" terminals should be connected together and then connected to the GND of the unbalance audio signal. When connecting to an unbalanced audio input from the MIC OUT connector (FIG. 8), wire the "+" terminal to the signal input, and the "GND" terminal to the signal ground.

Wiring the NXA-AVB/ETHERNET for Balanced Audio

Professional audio equipment will often use balanced audio inputs and outputs, usually on 3-pin "XLR" connectors. A balanced audio signal consists of a pair of wires carrying the audio signal in anti-phase with each other (if one wire carries a positive voltage, the other carries an equal and opposite negative voltage).

The advantage of balanced audio over unbalanced audio is its ability to reject external interference added as the signal is carried over the wire. The receiving equipment takes the voltage difference between the two wires as the input signal. Interference will usually get added to both wires equally, and so gets cancelled by the receiving equipment.

The 3 wires used in a typical XLR lead are often referred to as Ground, Live (Hot) and Return (Cold). "Live" and "Return" carry the "in-phase" and "out-of-phase" versions of the audio respectively. The pins of the XLR plug/socket are as follows:

•X = Ground

•L = Live (Hot)

•R = Return (Cold)

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