7
Operating Manual - SRA-120 Power Amplifier
SRA-120
Power
Channel 2
Protect
7.
REAR PANEL FEATURES
7.1
Inputs
The input of the SRA-120 amplifier is equipped
with balanced 1/4" tip-ring-sleeve (TRS) phone jacks and
balanced screw-terminal inputs. Each channel's connec-
tors are internally wired in parallel and may be used with
balanced or unbalanced connections. The nominal input
impedance (balanced) is 20K
Ω
and the maximum input
level is +22dBu.
Balanced Inputs
It is recommended that balanced input connec-
tions be used whenever possible to reduce ground-loop
and environment-induced hum and noise. The (+) signal
is on the tip of the phone jack, the (-) signal is on the ring,
and the shield is on the sleeve.
Unbalanced Inputs
If an unbalanced input connection is used, then
the (-) connection should be connected to ground. Use of
a mono (tip-sleeve) plug will automatically tie the (-)
connection to ground. Never float (leave unconnected)
pin 2 or pin 3 when using an unbalanced signal.
Input Ground
The CHASSIS GROUND terminal is internally
connected to the chassis, the AC earth ground, and the
power amplifier’s signal ground. The INPUT GROUND
terminal is tied to the 1/4" jack's sleeve. It is recom-
mended that the input and chassis ground terminals re-
main connected with the factory-supplied jumper strap.
tput Ch.1
(+)
(-)
Stereo
Mono
Norm
Bridged
0dB
-10dB
Input
Sensitivity
(+)
(-)
(+)
(-)
Channel 2
Input
Input is active balanced.
If unbalanced connection is used,
be sure to ground unused path.
Channel 1 (Mono)
Input
Bridged Mode:
Use Red Binding
Posts Only. Chan.2 is (+) and
Chan. 1 is (-). Do Not Connect
Either Output to Ground.
Input
Ground
45W/Ch.@8
60W/Ch.@4
Stereo Phone Plug
used for balanced
Tip (+)
Ring (-)
Sleeve (Ground)
Pins are
numbered
in the
connector
insert.
XLR Male
2 = (+)
3 = (-)
1 = (gnd)
(-)
(+)
(-)
(+)
Input
Output
Chassis Ground
Signal Ground
Terminal Strip
Balanced Audio Connectors
Figure 7.1: Balanced Input Connections (recommended)
Figure 7.1a: Unbalanced Input Connections
Mono Phone Plug
used for unbalanced
Tip (+)
Sleeve (Ground)
Pins are
numbered
in the
connector
insert.
XLR Male
2 = (+)
3 = (gnd)
1 = (gnd)
(gnd) (+)
(+)
Input
Output
Chassis Ground
Signal Ground
Terminal Strip
Unbalanced Audio Connectors
(gnd)
