Studio Technologies 742 2005 - Manual (Page 7)

Model 742 User Guide Issue 2, May 2005
Studio Technologies, Inc. Page 7
Model 742
associated with each main output bus.
They provide line-level signals capable
of driving balanced or unbalanced loads
of 600 ohms or greater. Separate studio-
quality audio compressor circuits are
provided to control the dynamic range of
each main output bus. An LED indicator
is associated with each compressor,
lighting whenever the circuit is actively
controlling signal level. Far from simple
“clippers,” the compressor circuits utilize
sophisticated laser-trimmed voltage-
controlled amplifier (VCA) integrated
circuits for quiet, low-distortion opera-
tion. To help minimize operator error no
compressor on/off switches are provided
on the Model 742’s front panel. Internal
configuration jumpers determine the com-
pressor circuits’ operating modes. From
the factory the jumpers are set so that the
compressors’ operating threshold is 6 dB
above the nominal +4 dBu output level.
This is an excellent general-purpose set-
ting for broadcast use where voice signals
are the primary audio content.
To meet the needs of other applications,
a technician can change the jumpers to
make the compressor threshold 2 dB
above the nominal +4 dBu. This could
prove useful when using the Model 742
with level-sensitive RF transmission sys-
tems. For other applications a technician
can set the jumpers to a third position
which completely disables the compressor
functions.
Monitor Section
The Model 742’s monitor section provides
two line-level monitor outputs and a
“stereo” headphone output. Monitor
outputs 1 and 2 are electrically balanced
with output buses 1 and 2, respectively,
assigned as their audio sources. The
headphone output has main output bus 1
as its left-channel source and main output
bus 2 as its right-channel source. Associ-
ated with the monitor section is a dual ro-
tary level control that allows independent
setting of the monitor output levels. The
level of the headphone output is always
adjusted using these controls. Internal
configuration jumpers are used to select
the operation of the line-level monitor out-
puts. They can either be “post” the con-
trols, allowing an adjustable output level,
or be set to fixed –10 or +4 dBu nominal
levels. This allows the monitor outputs to
be compatible with a variety of monitor
amplifiers, amplified loudspeakers, or to
even serve as an additional set of main
bus line-level outputs.
From the factory the monitor outputs are
configured to the “post” setting, enabling
them to “follow” the setting of the front-
panel level controls. This is appropriate
where monitor loudspeakers and associ-
ated power amplifier channels are used.
A technician can change the jumper
positions so that the monitor outputs are
electrically before (“pre”) the level con-
trols. Two jumper positions are available,
corresponding to –10 and +4 dBu nomi-
nal output levels. The “pre –10” position is
very useful when an amplified loudspeaker
that contains a user-accessible level con-
trol is connected. Examples of amplified
speakers that contain user level controls
include the popular Fostex® 6301-series.
With the jumpers set to the “pre –10”
position, only one level control—the one
on the amplified speaker—would be used
to set the speaker level. This can greatly
minimize operator confusion and enhance
performance.