Protective Circuits - Monacor STA-1504 Manual De Instrucciones

nected to the jack INPUT (8) via an adapter . The
XLR contacts 1 and 3 must be connected in the
adapter (e . g . the RCA / XLR adapters NTA-114
and NA-2MPMF from MONACOR are suitable) .
For the alternative connection of an unbalanced
signal to the plug-in screw terminals* (12) the
contacts 2 (SIGNAL−) and 3 (GND) must be con-
nected accordingly (compare fig . 4) .
5.2 Speakers
The maximum output power is obtained in
normal operation when connecting 4 Ω speak-
ers . It is also possible to connect 8 Ω speakers;
however, the output power will slightly decrease
in this case . In bridge operation the maximum
output power is obtained with an 8 Ω speaker .
The required rated power (P
min
is shown in the table fig . 5 .
Connect the speakers to the contacts 4 and
5 of the plug-in screw terminals* (12) according
to fig . 4 .
For bridge operation connect the positive
pole of the speaker to the positive terminal of
one output and the negative pole of the speaker
to the positive terminal of the other output of
the respective channel pair, as indicated on the
unit . (The positive terminal of one output of a
channel pair becomes the negative pole for the
speaker by signal inversion in bridge operation) .
When connecting the speakers, pay attention
to the same polarity of all speakers . However, if
it occurs that the phase will be extinguished at
the position of hearing because several chan-
nels amplify the same signal, and this cannot be
eliminated by correcting the speaker positions,
it may be necessary to reverse the polarity of
individual speakers .
Table fig . 5 also shows possibilities of con-
nection for several speakers to one output . For
this purpose it is indicated in each case which
rated power (P ) each speaker must have as a
min
minimum with the corresponding impedance (Z) .
When interconnecting several speakers, it
is especially important to observe the correct
connection of the positive and negative contacts
and that the total impedance per output is 4 Ω
as a minimum in normal operation, 8 Ω as a
minimum in bridge operation .
5.3 Power Supply
Connect the mains cable to the mains jack (14)
and the mains plug of the cable to a socket
(230 V/ 50 Hz) . Prior to the first switching-on,
turn the controls LEVEL (11) to the left stop .
6 Operation
6.1 Selecting the operating mode
With the switch NORMAL / BRIDGE (7) the de-
sired operating mode is selected for each chan-
nel pair:
6.1.1 Normal operation
If the switch is disengaged [the LED BRIDGE
(3) between the channels of the corresponding
channel pair does not light up], these two chan-
nels are operated independently of each other .
6.1.2 Bridge operation
If the switch is pressed in [the LED BRIDGE (3)
) of the speakers
between the channels of the corresponding
channel pair lights up], the input signal of the
second channel is additionally switched to the
first channel of the channel pair in an inverted
way . Thus, the voltage at the output is doubled
when the speaker is connected for bridge oper-
ation, as described in chapter 5 . An input signal
at the first channel of the pair is ignored . The
volume is adjusted with the control LEVEL (11)
and the filters are adjusted with the switches 9
and 10 (more details on this matter in chapter
6 .2) only at the second channel of the channel
pair . The examples in the figures 8 and 10 show
an application of the bridge operation .
6.2 Filters
Each channel has a switchable filter with selecta-
ble high pass or low pass characteristics . Thus,
this amplifier allows to built up 2-way systems in
which mid-high range speakers are operated via
channels with high pass filter and bass speakers
via channels with low pass filter .
With the switch FILTER / BYPASS (10) pressed,
the filter is active . Use the switch HI-PASS / LO-
PASS (9) to define if the filter is to be used as
a high pass (switch disengaged) or low pass
(switch pressed in) . The examples in figures 9
and 10 show an application of the filters .
6.3 Switching on /off
In order to prevent loud switching noise, always
switch on all other units in an amplifier system
before switching on the power amplifier, and
switch it off first after operation . Switch on
the amplifier with the POWER switch (5) . The
POWER LED (4) lights up . After switching on, the
switch-on delay is activated for a few seconds
to protect the speakers .
Specifications
Output power (RMS)
normal operation 4 Ω / 8 Ω
bridge operation 8 Ω
Input sensitivity for rated power
at 4 Ω
Input impedance
Frequency range
Filter crossover frequency
S / N ratio
Channel separation
THD
Ambient temperature
Power supply
Power consumption
Dimensions (W × H × D)
Weight
6.4 Level adjustment
Set the output of the mixer or preamplifier to its
rated level (0 dB) or to the highest undistorted
output signal . Turn up the controls LEVEL (11)
so far until the maximum desired volume is
reached . If the LEDs CLIP (1) show the overload
of the amplifier, slightly turn back the controls
of the corresponding channels .
CAUTION Never adjust the volume on the
accustomed to high volumes which do not
seem to be that high after some time . There-
fore, do not further increase a high volume
after getting used to it .
6.5 Ground lift switch
If an interfering hum noise can be heard with-
out a music signal, a ground loop may be the
reason for this . Ground loops may occur if two
units have contact in the rack both via the sig-
nal ground and via the earthed conductor of
the power supply or a conductive connection
of the housings . To separate the ground loop
thus occurring, set the ground lift switch (6) to
position 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 sig-
nal if the limit level is reached at the output .
Thus, distortions are prevented if the amplifier
is overloaded which could damage the speakers .
The speakers are switched off by an additional
protective circuit:
1 . for a few seconds after switching-on
(switch-on delay)
2 . if the amplifier is overheated
3 . if a DC voltage occurs at the output
If a short circuit occurs at a speaker output,
the CLIP LED (1) of the corresponding channel
lights up . If this is the case or if the speakers
are switched off during operation or if they are
not ready for operation after switching on, the
amplifier must be switched off and the cause
for the defect has to be eliminated .
All rights reserved by MONACOR
GmbH & Co. KG. No part of this instruction manual
may be reproduced in any form or by any means for
any commercial use.
STA-1504 STA-1506
4 × 160 W / 100 W 6 × 160 W / 100 W
2 × 320 W 3 × 320 W
0.7 V 0.7 V
20 kΩ 20 kΩ
12 – 60 000 Hz, −1.5 dB 12 – 60 000 Hz, −1.5 dB
240 Hz 240 Hz
> 80 dB > 80 dB
> 60 dB, 1 kHz > 60 dB, 1 kHz
< 0.1 % < 0.1 %
0 – 40 °C 0 – 40 °C
230 V/ 50 Hz 230 V/ 50 Hz
max. 1200 VA max. 1800 VA
482 × 132 × 310 mm, 3 RS 482 × 132 × 310 mm, 3 RS
16 kg 17.5 kg
amplifier very high . Permanent
high volumes may damage your
hearing! The human ear will get
INTERNATIONAL
®
STA-1508
8 × 160 W / 100 W
4 × 320 W
0.7 V
20 kΩ
12 – 60 000 Hz, −1.5 dB
240 Hz
> 80 dB
> 60 dB, 1 kHz
< 0.1 %
0 – 40 °C
230 V/ 50 Hz
max. 2400 VA
482 × 132 × 310 mm, 3 RS
19 kg
Subject to technical modification .
7