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Parallel operation
The parallel mode works mono. It serves thereto, to be able to connect lower impedances (down
to 2 Ω) as in normal operation without thereby overloading the power amplifier. For this you move
the mode toggle switch
j
to the "PARALLEL" position. In parallel operation you may only connect
the signal to the input CH-1. The device amplifies the input signal in both channels and puts it out
jointly via the outputs "CH-1" and "CH-2". Then you connect the two positive "+" speaker connec
-
tions together and the two negative "—" speaker connections together. Then you can connect, to
the device, one or more speakers.
Bridged mono operation
You can interconnect both power amplifier channels (bridge) and in this way you get a really power
-
ful single channel Power-Amp. For this you move the mode toggle switch
j
to the "BRIDGED"
position. In bridged mono operation both channels work together thus achieving effectively double
the performance of a single channel. Always be especially careful when operating bridged power
amplifiers because then a higher voltage is applied to the output. Also always take into considera
-
tion that the speakers must then have a considerably higher power rating!
You connect the signal to be amplified to the input CH-1. You connect one or more speakers to the
two red speaker terminals.
The red speaker connection of the channel CH-2 is thus "in Phase" with the input. That means:
Speaker "
+
"
=>
"
+
"
Pole channel
CH-2
Speaker "
—
"
=>
"
+
"
Pole channel
CH-1
When in operation you control the volume only with the input level controller CH-1
w
, the input
level controller CH-2
r
then has no function. The input signal from channel CH-2 is disconnected
in this operational mode.
You must never earth either of the two speaker wire cores with bridged
operation since both cores are "hot". If you use a Patchbay on the output
side, all connections must be insulated from each other and from earth/
ground.
8. Selecting input sensitivity
Here you set the input level by which the power amplifier should deliver its power rating "0,77V"
for devices with -10 dBV outputs or "1,4V" for connection of devices with +4 dBV outputs. Often
several amplifiers are operated simultaneously. If you set this switch to „26db“, all connected ampli
-
fiers will amplifiy the input signal with the same power. So you can combine different amplifiers of
the S-series and get always the same output volume.
9. Switching on
Press the POWER switch
o
on the front panel to the "I" position to switch the device on. To switch
the device off again move the switch to the "O" position.
10. Additional operational information
Power controller
The input level controllers CH-1
w
and CH-2
r
on the front panel determine the signal amplifica
-
tion in the respective channel. If possible turn this controller all the way to the right end stop (= 0 dB
attenuation) in order to enable the system to achieve its optimal headroom. Professional power
amplifiers then deliver their power rating so long as an input voltage of 0,775 V and/or 1,4 V
(depending on the switch setting for the input sensitivity) is applied.
Summary of Contents for S- 75
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