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Operating Manual - SRA-120 Power Amplifier
8
In situations where the power amp and its signal
source are separated by great distances, a ground voltage
difference may exist between the amp’s chassis ground
and the input cable’s ground. Connection of these two
grounds through the jumper strap may cause large ground
currents to flow (which is known as a ground loop), caus-
ing a hum noise in the amp’s output. Unless you have
such a situation with a hum problem that cannot be solved
by using balanced input connections, the ground jumper
strap should remain in place.
7.2 Input Sensitivity Switch
This switch selects between a 0 dBu input sensi-
tivity in the "out" position for use with professional au-
dio sources, and -10 dBu input sensitivity in the "in" po-
sition for use with low line-level sources such as tape
decks, CD players, DAT machines, etc.
7.3 Normal/Bridging Switch
This switch selects between NORMAL mode in
the “out” position where both outputs are in-phase with
their respective inputs, and BRIDGED mode in the “in”
position where channel 1 output is switched out of phase
with it's input. In BRIDGED mode, the channel 2 red bind-
ing post becomes the (+) in-phase speaker output terminal
and the channel 1 red binding post becomes the (-) out-of-
phase speaker terminal. To properly operate in bridged
mono mode, the Mono switch must also be selected.
7.4 Stereo/Mono Switch
This switch selects between stereo mode in the
"out" position and mono mode in the "in" position. In
mono mode, channel 1 input is sent to both amplifier chan-
nels, and is controlled through the channel 1 level con-
trol.
7.5 Speaker Outputs - Binding Posts
A pair of dual banana binding posts provide the
stereo speaker outputs. The minimum load impedance is
4 ohms per channel in normal mode, and 8 ohms in bridged
mode. In BRIDGING mode, the channel 2 red binding
post is the (+) in-phase speaker output terminal and the
channel 1 red binding post becomes the (-) out-of-phase
speaker terminal.
CAUTION! NEVER CONNECT THE TWO RED
BINDING POSTS TOGETHER OR CONNECT
EITHER RED BINDING POST TO A BLACK
BINDING POST!
8. TYPICAL APPLICATIONS
8.1 Stereo Sound Reinforcement System
In this situation, the audio source feeding the SRA-120 is a professional level (0dBu) stereo mixer. All three
mode switches should be in the "out" position.