Multichannel PA Amplifier
These instructions are intended for experts with
specific knowledge in PA technology. Please read
these operating instructions carefully prior to
operation and keep them for later reference. All
operating elements and connections described
can be found on the fold-out page 3.
1 Operating Elements and
Connections
1.1 Front panel
1 LED CLIP lights up if the respective channel
is overloaded and in case of short circuit of
the respective output
2 LED row for level indication
3 LED BRIDGE lights up when the switch for
the operating mode (7) of the corresponding
channel pair is pressed
4 POWER LED
5 POWER switch
1.2 Rear panel
6 GROUND LIFT switch
position GND: signal ground and housing
ground are connected
position LIFT: signal ground and housing
ground are separated
7
Operating mode switch for the respective
channel pair
switch pressed: bridge operation
not pressed: normal operation
8 INPUT jacks as XLR jacks for units with line
level (contact configuration see fig. 3)
9
Selector switches for the filter mode of each
channel
switch pressed: low pass filter (LO-PASS)
not pressed: high pass filter (HI-PASS)
10
Switches for activating / deactivating the filter
for the respective channel
switch pressed: filter on (FILTER)
not pressed: filter off (BYPASS)
11 Volume control for the respective channel
12 Plug-in screw terminals* for the respective
channel (contact configuration also see
fig.4)
contacts 1 to 3:
alternative INPUT, directly connected to
the respective XLR input (8); also suitable for feeding the signal through to the
input terminals of other channels
contacts 4 and 5:
speaker connections OUTPUT
13 Fuse holder; only replace a blown fuse by
one of the same type
14 Mains jack for power supply for connection
to 230 V/ 50 Hz
2 Safety Notes
This unit corresponds to all relevant directives of
the EU and is therefore marked with .
WARNING The unit is supplied with hazard-
ous mains voltage. Never make
any modifications on the unit and
do not insert anything through
the air vents! This may cause an
electric shock.
There is a hazard of contact at the speaker
connections with a dangerous voltage during
operation. All connections must only be made
or changed with the unit switched off.
•
The unit is suitable for indoor use only. Protect
it against dripping water and splash water,
high air humidity, and heat (admissible ambient temperature range 0 – 40 °C).
•
Do not place any vessels filled with liquid, e. g.
drinking glasses, on the unit.
•
The heat being generated in the unit must be
carried off by air circulation. Therefore, the air
vents at the housing must not be covered.
•
Do not set the unit into operation, or immediately disconnect the mains plug from the
mains socket if
1.
there is visible damage to the unit or to
the mains cable,
2. a defect might have occurred after a drop
or similar accident,
3. malfunctions occur.
The unit must in any case be repaired by
skilled personnel.
•
Never pull the mains cable to disconnect the
mains plug from the mains socket, always
seize the plug.
•
For cleaning only use a dry, soft cloth, by no
means chemicals or water.
•
No guarantee claims for the unit and no liability for any resulting personal damage or material damage will be accepted if the unit is used
for other purposes than originally intended, if
it is not correctly connected, operated, or not
repaired in an expert way.
If the unit is to be put out of operation
definitively, take it to a local recycling
plant for a disposal which will not be
harmful to the environment.
3 Applications
The PA multichannel amplifier is suitable for
versatile applications, e. g. on stage, in the discothèque, or in the catering trade. The amplifier
has four (STA-1504), six (STA-1506), or eight
(STA-1508) separate channels which can also be
combined in pairs in bridge operation to increase
the output power. High pass filters and low pass
filters which can individually be switched for
each channel allow the use as a 2-way system
without additional crossover network. Extensive
protective circuits protect the amplifier and the
connected speakers.
Page 3 shows five examples for versatile applications:
Fig. 6: Independent operation of four chan-
nels with four different input signals.
Fig. 7: Channel group of which the input sig-
nal of the first channel is fed through
to the inputs of the other channels; the
volume can independently be adjusted
for each channel
Fig. 8: Combination of channel pairs in bridge
operation to increase the output
power
Fig. 9: Division of two input signals in two fre-
quency ranges each for separately driv
ing mid-high range speakers (HIGH)
and bass speakers (LOW) with separate
volume control of all outputs
Fig. 10: A combination possibility of the con-
figurations shown before, e. g. for a
PA output and a monitor way: signal
B drives a mid-high range speaker via
channel CH2; the bass part which
generally requires a higher amplifier
power is amplified by channels CH3
and CH4 in bridge operation. Signal A
is independently amplified via channel
CH1.
These are only some examples for the configuration possibilities of the amplifier. Numerous
other combinations are possible, especially for
the 6-channel or 8-channel models.
4 Installaton
The amplifier is designed to be mounted into a
rack (482 mm / 19”), but it may also be used as
a table top unit. In any case air must be allowed
to move freely through all air vents so that a
sufficient cooling is ensured.
4.1 Rack installation
For the rack mounting 3 rack spaces = 133 mm
are required. Additional space should remain
above and below the amplifier in order to ensure
sufficient ventilation.
In order to prevent that the rack becomes
top-heavy, the amplifier has to be mounted in
the lower part of the rack. The front plate alone
is not sufficient as a secure fastening. The unit
has to be additionally supported by side rails or
a bottom carrier plate.
5 Connecting the Amplifier
All connections must only be made if the unit
is switched off!
5.1 Inputs
Connect the output of a preamplifier or mixer
to the XLR jacks INPUT (8) or plug-in screw terminals* (12). Both connections are designed for
balanced signals; the contact configurations are
shown in figures 3 and 4. It is also possible to
pick up an input signal which is fed to the XLR
jack (8) of a channel from the plug-in screw
terminals* (12) of the same channel and to feed
it through to the input of another channel (as
in case of examples in figures 7, 9, and 10). For
this purpose connect in each case the contacts 1
(SIGNAL+) and 2 (SIGNAL−) of the plug-in screw
terminals* of both channels with each other. The
contacts 3 (GND) must not be connected externally as they are already internally connected.
The input signal should have line level. For rated
power of the amplifier an input signal of 0.7 V
is required as a minimum.
If only an unbalanced signal is available at
the output of the signal source, it can be con-
* For better handling, the connection terminals can be
removed from their plug-in connection.