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SECTION
I
INTRODUCTION
FIGURE
1-1.
MODEL 1178 FRONT
PANEL.
1.1
DESCRIPTION
The Model 1178
is a
two channel version of the very successful
1176LN Peak Limiter used
in
many recording
studios,
broadcast
stations, sound reinforcement installations, etc. around the world.
The Dual Peak Limiter was designed for those applications where two
channels of program material are processed, and the balance
of these
audio channels must be maintained.
The two limiters inside the
Model 1178 are matched to assure the high degree of tracking neces-
sary for critical stereo applications.
Single adjustments of attack and release time affect both chan-
nels simultaneously, while the input and output level controls are
adjusted independently.
In the
stereo mode,
a
front panel switch
allows the two limiters' gain reduction amplifiers
to
be linked
together such that the audio signal with
the
larger peak-to-peak
amplitude causes the same amount of gain reduction
in
both channels.
On
the other hand,
when switched
to single
mode operation, the two
limiters process the signals independently.
This provides
the user
with exceptional flexibility
in operation.
The Model 1178 was designed to have performance characteristics
similar
to the
single channel 1176LN.
Limiting
is
accomplished by
utilizing FET's
as
voltage variable resistors.
Unique circuitry
permits severe limiting without added distortion
and the
compression
ratio may be optimized for various program materials.
The gain
structure throughout the Model 1178 maintains
an
excellent signal-
to-noise ratio
at
normally used control
setting.
Dual,
backlighted front panel meters may be switched
to read
either the amount of gain reduction, or the output signal level
referenced
to +4
dBm or +8
dBm.
Also switch selectable
are the
meter reading characteristics: either indicating average signal
(VU
ballistics)
or peak.
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1
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