Protective Circuits; Specifications - IMG STAGE LINE STA-250 Instruction Manual

and a load impedance assumed. The specified
load impedance is always 8 Ω after switching on
the amplifier.
If 4 Ω speakers are connected, press the
button LOAD 4/ 8 OHM (4) to adapt the calcula-
OUT 4Ω
tion. The display now shows
power is calculated for a load impedance of 4 Ω.
To switch back, press the button repeatedly until
OUT 8Ω
is shown. The display switches back to
standard indication a few seconds after pressing
the last button.
Note: The power indicated is not effective in
bridge operation.
6.6 Groundlift switch
If an interfering hum noise can be heard without
a music signal, a ground loop may be the reason
for this. Ground loops may occur if two units
have contact both via the signal ground and via
the earthed conductor of the power supply or a
conductive connection of the housings in the
rack. To separate the ground loop thus occur-
ring, set the switch GROUNDLIFT (13) to posi-
tion LIFT.

7 Protective Circuits

The protective circuits are provided to prevent
damage to the speakers and the amplifier. The
integrated level limiter reduces the input signal
when the limit level is reached at the output. If
the amplifier is overloaded, distortions can thus
be prevented which could damage the speakers.
With the switch LIMITER (11) this function can
be switched on and off [indication
LIMT OFF
(g)]. If the limiter is active, the LIMITER
LED (2) of the corresponding channel lights up.
Due to an additional protective circuit the
speakers are separated from the output of the
channel concerned. If it is active, the correspond -
ing red PROTECT LED (2) lights up:
1. for a short time after switching-on (switch-on
delay)
2. in case of overload / overheating, in this case,
PROT OFF
the indication (c) changes to
ON
on the display (3) additionally
After cooling-down, the amplifier channel
continues its operation independently.
In standard operation the display shows the tem-
perature at the power transistors separately for
both channels (d). With higher temperatures the
fan control ensures that the fan of the channel
concerned runs at higher speed.
If a PROTECT LED does not extinguish after
switching-on or after cooling-down after an over-
load, or if the circuit breaker (14) has been
released, the amplifier must be switched off and
the cause for the defect must be eliminated. If
required, reset the protective switch by pressing
it down with the unit switched off.

8 Specifications

Model
(k) and the
RMS output power
stereo, parallel at 4 Ω
stereo, parallel at 8 Ω
bridge operation 8 Ω
Input sensitivity for
rated power at 8 Ω
Input impedance
Frequency range
High pass filter / low pass filter
Channel separation
S / N ratio
THD
Connections
inputs
outputs
Ambient temperature
Power supply
Max. power consumption
Dimensions (W × H × D)
Weight
LIMT ON
or
8.1 Block diagram
PROT
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manual may be reproduced in any form or by any means for any commercial use.
STA-250
2 × 700 W
2 × 500 W
1200 W
45 – 9600 Hz, 18 dB/ octave
> 35 dB
> 78 dB
XLR and 6.3 mm jacks, balanced
screw terminals and speaker jacks
(Speakon compatible)
230 V~/ 50 Hz
2900 VA
482 × 100 × 455 mm,
2 RS
19.1 kg
® INTERNATIONAL GmbH & Co. KG. No part of this instruction
STA-260
2 × 1000 W
2 × 600 W
1600 W
1 V
20 kΩ
20 – 20 000 Hz
> 45 dB
> 84 dB
< 0.1 %
0 – 40 °C
230 V~/ 50 Hz
3680 VA
482 × 100 × 455 mm,
2 RS
18.9 kg
Subject to technical modification.
GB
9