9
for common mode interference signals and to give a professional connection to external equipment. It
is essential for optimal use of these specifications that a professional grade, balanced two-core
screened cable is used.
Source Balanced Pin 2 hot
In accordance with international standards, 3-pin XLR style input connectors are used, with pin
2 being designated the ‘in-phase’ or ‘hot’ terminal and pin 3, the ‘out of phase’ or ‘cold’ terminal.
Pin 1 is connected to the chassis ground and
must
be connected to the screen of the audio
interconnecting cable. This is necessary to ensure proper compliance with European Standards for
Electromagnetic Compatibility. Pin 1 carries no signal voltages or currents and is provided purely for
screening purposes. It should not be connected to either pin 2 or pin 3.
Source Unbalanced Pin 2 Hot
If the equipment providing the audio signal has an unbalanced output, then the interconnecting audio
cable should be wired so that the hot output of the source is connected to pin 2 of speaker input XLR
and the ground of the source connected to pin 3. The screen of the interconnecting audio cable should
be connected to pin 1 of the input connector
only.
There must be no connection betwee n the
ground connection of the unbalanced output and the pin 1 ground connection of the input
connector.
Source Unbalanced Phono
If the source output is a phono socket, then the centre pin of the phono plug should be wired to pin 2
of the speaker input XLR and the outer phono casing to pin 3. The wire from pin 1 of the XLR will
not be connected to the terminals of the phono plug. Strict adherence to this will help to eliminate
ground loop hums and RF break through.