Studio Technologies 742A - Manual (Page 10)

Issue 1, July 2012 Model 742A User Guide
Page 10 Studio Technologies, Inc.
Audio Mixer
Monitor Output Modes
The line-level monitor outputs can be
configured to operate from one of three
modes:
• From the factory the monitor outputs
are set to follow the position of the front-
panel rotary level controls. This mode of
operation is referred to as being “post”
the level controls.
• An alternate configuration is specifically
provided for use in applications where
amplified loudspeakers with built-in
user level controls are connected.
This “pre” level-control mode provides
fixed nominal output levels of –10 dBu.
This prevents the confusing situation
of having multiple level controls—the
Model 742A’s and the amplified speak-
ers’—both impacting the level of a
speaker. In this case the Model 742A’s
front-panel controls will only impact the
headphone output.
• A third configuration provides a “pre”
level-control mode with a fixed nominal
output level of +4 dBu. This can be use-
ful for applications where an additional
set of main outputs is required. Except
for using ¼-inch 3-conductor jacks
(versus XLRs) the monitor outputs are
identical in quality as compared to the
main outputs. Again in this mode the
Model 742A’s front-panel controls will
only impact the headphone output.
Reference Tone Frequency
From the factory the frequency of the refer-
ence tone is configured to be 400 Hz. This
is a nice alternative to the more-typical
1 kHz, a frequency which can soon be-
come very annoying to a listener’s ears. In
most cases 400 Hz will be perfectly accept-
able, and actually preferred. But in those
situations where 1 kHz is necessary, two
configuration jumpers are provided to shift
the frequency range so that the oscillator
circuitry can be calibrated for 1 kHz.
Configuration Wrap-Up
If it is determined that any configuration
changes are required, they should now be
performed. For specific details on how to
make configuration changes, refer to the
Technical Notes section of this guide. The
details provided should make the process
simple and relatively painless.
It’s highly recommended that a Model
742A’s actual configuration be confirmed
prior to installation. Even factory-fresh units
can “mysteriously” end up having their
default configurations changed prior to
actual installation. The same “gremlin” that
borrows and doesn’t return tools, drinks
your favorite soda that you left in the tech-
shop refrigerator, and pulls important patch
cords has been known to sneak inside
equipment and revise settings!
Installation
In this section you will be installing and
interconnecting the Model 742A. The
one-rack-space unit will be installed in an
equipment rack. Audio input and output
connections will be made using the 3-pin
XLR connectors and ¼-inch 3-conductor
jacks. In most cases AC mains power will
be connected by means of a detachable
cord set that is compatible with the Model
742A’s 3-pin IEC 320 C14 inlet connector.
Some applications may warrant connection
of a source of 10 to 18 volts DC which can
be made by way of a 4-pin XLR connector.
The DC source can be used to power the
Model 742A or it can serve as a backup
source for a connected AC mains source.