TOA Electronics TX2 - Manual (Page 4)

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Input connections.
As with other devices of its type, the TX2 controller is inserted in the audio chain
between the last link of audio source (mixing console, preamp, CD player, etc.) and
the power amplifiers.
The two audio inputs are the 3 pin female XLR connectors on the rear panel, marked
L for left and R for right. On each connector the signal is received between pins 2
and 3 and pin 1 is grounded.
When the device connected at the input (e.g. console) and at the output (i.e.
amplifier) are both balanced, there is no hot and cold pin to worry about : the TX2 is
neutral polarity with pin to pin connections (pin 1 to pin 1, pin 2 to pin 2, pin 3 to pin
3). Note that pin 1 connection should be made using the cable shield.
Where a device with an unbalanced output (e.g. hi-fi CD player or preamplifier) is
connected to the input of the TX2, the signal should be applied to either pin 2 or pin
3 of the input XLR, according to which pin is ‘hot’ on the amplifier connected at the
output. The unused signal pin (3 or 2 respectively) should then be linked to pin 1 for
grounding (see Fig. 2).
Figure 2. Input connections from an unbalanced source
Output connections.
The audio outputs are the three 3 pin male XLR connectors on the rear panel. Two of
them (marked L for left and R for right) are the output channels for the main system,
while the third one (marked MONO SUB OUT) is for the optional sub-bass system.
On each of these connectors the signal is applied between pins 2 and 3 and pin 1 is
grounded.
When devices connected at the input (e.g. console) and at the output (i.e. amplifier)
are both balanced, as said previously, the controller is neutral polarity with pin to pin
connections (pin 1 to pin 1, pin 2 to pin 2, pin 3 to pin 3).
Where amplifiers with unbalanced inputs are used, the hot pin of the amplifier input
should be connected to either pin 2 or pin 3 of the TX2 output XLR, according to
which pin is ‘hot pin’ on the device connected at the input. The unused signal pin (3
or 2 respectively) should then be linked to pin 1 for grounding.
Note however that the use of amplifiers with unbalanced inputs - rather unusual for
professional products - is not recommended, among other drawbacks it will cause the
level to drop by 6dB on the outputs of the controller.
Operation with and without a sub-bass system.
The unit should be powered (green LED showing on the front panel) before being
connected , or the amplifiers should be turned off, to avoid any switch noise or power
surge that could damage the loudspeakers. Similar precautions should be taken
when power is switched off.