– 10 –
XLR Balanced Input
Check output from source for proper signal polarity
Pin 1
= GND
Pin 2
= (+)
Pin 3
= (–)
INPUT
FROM
SOURCE
XLR Unbalanced Input
Connect (–) and GND (shield) terminals at
both ends of cable to
prevent unstable amplifier operation
Pin 1
= GND
Pin 2
= (+)
Pin 3
= GND
INPUT
FROM
SOURCE
1
2
3
GND
–
+
1
2
3
SHIELD
+
XLR WIRING CONFIGURATIONS
Using the balanced XLR input is recommended for installations where long cable runs are used or when the potential for stray
electromagnetic fields from other wires exists. There are balanced and unbalanced methods in which the XLR inputs can be used.
The first method is an XLR Balanced Input using 3-conductor cable with signal carried on the first conductors, equal in amplitude
and opposite in phase, and the third conductor being a ground "drain". In this configuration, noise common on both phases of
the signal is effectively "canceled" out. The second method is an XLR Unbalanced Input using 2-conductor cable with the signal
carried in the center conductor and the ground carried on the shield. Many popular mixers use unbalanced outputs and can be
used with the XLR balanced input. However, in this type of configuration we recommend using twisted pair cable or short cable
lengths to prevent residual ground noise.
I
NPUT SWITCH
The unbalanced input uses a conventional RCA phone jack. Move the input switch to RCA UNBALANCED to use this jack. The
balanced input jack is an XLR plug. The XLR jack is connected according to the IEC and AES standard. Move the input switch
to XLR BALANCED to use this jack.
Unbalanced Input
Move input switch to RCA UNBALANCED to use
RCA connectors
-27
-24
-21
-15
-12 -9
-6
-3
0dB
-30dB
50
60 70 80
90
100
120
14
0
40HZ
2 3 4
Phase @ 80Hz
- 270˚ 2
- 180˚ 2 + 3
- 90˚
2 + 3 + 4
XLR Bal
OFF
0˚
ALL OFF
-18
Signal In
(balanced)
Gain
dB relative to
max gain in
3dB steps
Signal In
(Unbalanced)
Low Pass
RCA Unbal
Balanced Input
Move input switch to XLR BALANCED to use the
XLR connectors
-27
-24
-21
-15
-12 -9
-6
-3
0dB
-30dB
50
60 70 80
90
100
120
14
0
40HZ
2 3 4
Phase @ 80Hz
- 270˚ 2
- 180˚ 2 + 3
- 90˚
2 + 3 + 4
XLR Bal
OFF
0˚
ALL OFF
-18
Signal In
(balanced)
Gain
dB relative to
max gain in
3dB steps
Signal In
(Unbalanced)
Low Pass
RCA Unbal
