9
Bridge Mode
The Servo 120 provides a rear-panel switch that allows it to be used in a Bridge
mode. When this switch is placed in the “Off” (left) position, the Servo 120
functions as a true stereo amplifier, where both of the two independent amplifier
channels (left and right) can receive different input signals and produce
independent output signals. However, when the switch is placed in the “On”
(right) position, both amplifier channels process only the signal present at the left
input, thus producing a single output signal with a true 120 watt output (into 8
ohms).
The illustration on the left shows how this works. In bridge mode, the polarity
(phase) of the right output signal is reversed relative to that of the left output
signal. Both channels then process the same signal, with the speaker load
connected so that power is derived from both channels. The effective voltage
swing seen by the load is thus doubled so that the power output is doubled.
When using the Servo 120 in Bridge mode, be sure to connect each
loudspeaker as shown in the illustration below (and as silkscreened on the rear
panel), with the red (+) terminal of the left channel connected to the positive
input of the speaker and the red (+) terminal of the right channel connected to
the negative input of the speaker. Do not use the black ground-) output
terminal of either channel (the speaker load must “float” away from the
amplifier chassis).
BRIDGE
OFF
ON
BRIDGE
OFF
ON
F
U
S
E
F
U
S
E
SERVO 120 STEREO AMPLIFIER
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
!
SAMSON
BALANCE
RIGHT
LEFT
M0N0
BALANCE
AC INPUT
USA & CANADA 115V~60HZ 200W
EUROPE & UK 230V ~ 50HZ 300W
USA & CANADA
2.5A/125V (115V)
EUROPE & UK
1.5A/250V (230V)
+RIGHT
GROUND
LEFT+
MONO (8
Ω
)
-
+
+
-
WARNING: Bridge mode is to be used only when the Servo 120 is
connected to an 8 ohm speaker load. Use of Bridge mode with speaker
loads of 4 ohms or less can result in severe damage to the unit due to
excessive heat and current limiting and will void your warranty!
INPUT
LEFT(+)
OUTPUT
RIGHT(+)
OUTPUT
