Studio Technologies 742A - Manual (Page 8)

Issue 1, July 2012 Model 742A User Guide
Page 8 Studio Technologies, Inc.
Audio Mixer
to be compatible with a variety of moni-
tor amplifiers, amplified loudspeakers, or
even to serve as an additional set of main
bus line-level outputs.
From the factory the Model 742A’s monitor
outputs are configured to the “post” set-
ting, enabling them to “follow” the setting
of the front-panel level controls. This is
appropriate where monitor loudspeakers
and associated power amplifier channels
are used. A technician can change the
jumper positions so that the monitor out-
puts are electrically before (“pre”) the level
controls. Two jumper positions are avail-
able, corresponding to –10 and +4 dBu
nominal output levels. The –10 position
can be very useful when connecting the
monitor outputs to amplified loudspeakers
that contain user-accessible level controls.
Examples of amplified speakers that con-
tain user level controls include the popular
Fostex® 6301-series. With the jumpers set
to the –10 position, only one level con-
trol—the one in the amplified speaker—
would be used to set that speaker’s level.
This can greatly minimize operator confu-
sion and enhance performance.
When the unit is configured for +4 opera-
tion the monitor outputs are again “pre”
the level controls, but this time with a nom-
inal level of +4 dBu. This can be used for
various applications, including providing
an additional set of main bus outputs. In
certain cases this may eliminate the need
for an external distribution amplifier to be
included as part of the installed system.
Metering
As previously discussed, individual dual-
color signal present/peak LEDs are as-
sociated with the four mic/line input and
the four line input channels. In addition,
two 10-segment LED meters provide an
indication of audio-signal levels present
on the main output buses. These meters
use three LED colors: green, yellow, and
red. The LEDs are calibrated such that the
actual output level, in dBu, is indicated.
Two additional LEDs, one for each output
bus, display the status of the compressor
circuits. They light whenever the compres-
sors are actively controlling the dynamic
range of the audio signals.
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 742A’s front panel allows the tone
to be connected to the main output buses.
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,
without interfering with normal operation
of the main output buses.
Mounting, Connectors, and
Power
The Model 742A requires one space in a
standard 19-inch rack. Industry-standard
XLR and ¼-inch 3-conductor connectors
are used for all audio interconnections.
To maximize reliability, all connectors
were carefully selected from among
premium-grade models. For example, the
XLR connectors feature metal shells and
are manufactured by Neutrik®. AC mains
power can be connected directly to the
Model 742A by way of a standard 3-pin