Studio Technologies 740 - Manual (Page 7)

Model 740 User Guide Issue 3, May 2004
Studio Technologies, Inc. Page 7
Model 740
to be monitored. This allows monitoring
of the main audio bus, along with two
external monaural audio sources. These
external monitor inputs are intended to
be connected to devices such as off-air,
microwave, or satellite receivers. Alternate-
ly, other mobile broadcast support equip-
ment, such as a PC-based editing system,
can be connected.
Unique to the Model 740 is the ability to
configure the monitor output to meet the
needs of the “real world.” This is accom-
plished by using an internal 3-position
configuration jumper to select the monitor
output mode. From the factory the monitor
output is configured to “follow” the setting
of the front-panel level control. In addition,
the monitor output mutes whenever a pair
of headphones is plugged into the front-
panel jack. A technician can change the
jumper position so that the monitor output
still follows the setting of the front-panel
level control, but is not impacted by use
of the front-panel headphone jack.
A third jumper position allows a technician
to configure the monitor output such that
it is electrically before (“pre”) the level
control. As with the previous mode, the
output isn’t impacted by use of the head-
phone output. This mode is very useful
when an amplified loudspeaker that con-
tains a user-accessible level control is
connected. Examples of amplified speak-
ers that contain user level controls include
the popular Fostex® 6301-series. With the
jumper in the pre-level-control 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 while still
utilizing the resources of the Model 740’s
monitor section.
Metering
A 10-segment LED meter provides an
indication of audio-signal level. An internal
selection jumper determines the audio
source for the meter. From the factory
the meter is set to monitor the signal level
of the main audio bus. A technician can
change the configuration so that the meter
monitors the source selected by the moni-
tor section’s 3-position switch. In this way
the level of the main audio bus, as well
as the two external monitor sources, can
be displayed by the meter.
Reference Tone
A sine-wave audio tone is provided for
alignment and reference use. From the
factory the tone is configured for 400 Hz.
If required, a technician can revise the
frequency to be 1 kHz. A button on the
Model 740’s front panel allows the tone
to be connected to the main audio bus.
In addition, a dedicated reference tone
output is also provided. This continuous
source of sine-wave signal is accessed by
means of a balanced line-level output on
the back panel. The dedicated reference
tone output is intended to provide a setup
or test signal that is available at all times,
and without interfering with normal opera-
tion of the main audio bus.
Mounting, Connectors, and
Mains Power
The Model 740 requires one space in
a standard 19-inch rack. Industry-stan-
dard XLR-type and ¼-inch 3-conductor
audio connectors are used for all audio
interconnections. To maximize reliability,
all connectors were selected to be pre-
mium grade. For example, the XLR-type
connectors feature metal shells and are
manufactured by Neutrik. AC mains power