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7. Contour Switch:
The "in" position of this switch provides 10 dB boost
at 100 Hz and 6 dB boost at 10 kHz. The "out" posi¬
tion removes boost from the system.
8. Power LED:
Indicates when AC power is being supplied to the unit.
9. Power Switch:
Depress to "on" position to turn on.
10
11
13
12
REAR PANEL CONNECTIONS:
10. Mute Control:
These connections allow control over the internal mute
control circuitry. To enable muting, connect the GND
terminal to the ENABLE terminal. This will allow the
MIC 1 signal to mute the MIC 2/AUX 1 and AUX 2
channels. Muting of the AUX channels can be selec¬
tively disabled internally by moving the two-circuit
jumpers as shown in Fig. 3. To disable muting of the
MIC 2/AUX 1 channel, move the two circuit jumper
on HDR 100 to the position shown by the arrow in Fig.
3. To disable muting of the AUX 2 channel, move the
two circuit jumper on HDR 200 to the position shown
in Fig. 3. External muting of the AUX channels is also
possible by connecting a normally open switch from
the GND terminal to the EXT terminal. See Fig. 4.
11. External Master Volume:
These terminals allow connection of an external
volume control. To gain complete control of volume
from the external volume control, the front panel
Master Volume control must be set to maximum. The
external volume control should be connected as
shown in Fig. 5.
1 2 . MIC Inputs:
The input connections are configured to allow Low Z,
High Z, Balanced, and Unbalanced microphones to
be connected to the system. XLR, as well as screw,
terminals are provided for Low Z balanced inputs.
Screw terminals are also
provided for High Z
microphone connection. See Fig. 6 and 7.
13. Auxiliary inputs:
The AUX 1 and AUX 2 inputs are made through these
two jacks. These line inputs are provided to input any
line level signal, such as background music from a
taoe or tuner outout.
14. Outputs:
A direct output, as well as several Transformer outputs,
are provided to allow the proper interface between the
amplifier and the speaker system. The direct output
allows direct connection to a 4 ohm speaker system.
To use this output, disconnect the jumper between the
4 ft terminal and the XFMR terminal. Connect the
speaker {or speakers) from the GND terminal to the
4 ft terminal.
8 ohm, 25 volt and 70 volt outputs are also provid¬
ed. To use these outputs, the jumper between OUT
and XFMR must be installed. For 8 ohm speaker
systems, connect between the COM terminal and the
8 ohm terminal. 25V and 70V outputs are also provid¬
ed for "constant voltage" speaker distribution systems.
The 25V output connection is between the COM ter¬
minal and the 25V terminal. One more output is pro¬
vided on the UMA Series amplifiers. This is a balanc¬
ed, transformer isolated line level output. This output
is provided for direct connection to "music on hold"
systems, booster power amplifiers, etc. This output is
designed to deliver IV RMS into a 600 ohm load. See
Fig. 8 through 11 for possible output connections.
NOTE: Due to the high gain and frequency response
of the UMA Series amplifiers, it is necessary that the
input cables be routed away from the output cables
to prevent instability. An external shield is provided
to aid in the separation of input and output cables and
to assure stability under adverse conditions
associated with the wide range of applications in
which the amplifier might be installed. Under no cir¬
cumstances should this shield be modified or re-
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