Studio Technologies 742A - Manual (Page 24)

Issue 1, July 2012 Model 742A User Guide
Page 24 Studio Technologies, Inc.
Audio Mixer
Warning: Protect your ears! The
Model 742A is capable of driving
headphones to extremely high sound
pressure levels. Hearing experts
encourage caution against continu-
ous extended play, especially at high
levels. Polka music has been found
to be especially dangerous, so
please be careful.
Practical Operating Tips
Now that we’ve reviewed all the sections
that comprise the Model 742A, it’s time to
actually use the unit. The following para-
graphs provide suggestions regarding
how to best use the Model 742A.
Setting the Output Bus Operating
Levels
The two output bus master level controls
allow the overall gain structure of the main
audio buses to be set. Correctly setting
these controls ensures that the best audio
quality will be achieved. In most cases
simply setting both controls to the unity
gain position is appropriate; the unity gain
position is clearly marked with a “U” on
the front panel.
Signal Present/Peak LEDs
Dual-color status LEDs are associated
with each of the four mic/line inputs as
well as the four line-level inputs. Simply
stated, lighting green is fine, lighting red
is bad. When a mic/line input channel has
its input sensitivity (mic/line) switch and
level control set correctly only the LED’s
green color should light. Each line-level
input channel should have its level con-
trol set so that only the LED’s green color
lights. With both types of input channels,
signal peaks may cause an occasional
red “flash,” but sustained red lighting
indicates that audio performance is being
compromised.
Compressor Active LEDs
Compressor active LEDs, one for each
output bus, are located directly to the right
of the level meters. They will light with a
yellow color whenever dynamic range
control is taking place. If the compressors
have been configured not to operate (dis-
abled) then obviously the LEDs will never
light. If the compressors are enabled, typi-
cal operation should find the LEDs light-
ing on occasion, or even frequently, on
signal peaks. But the LEDs should never
light continuously. If this is the case the
input level controls should be adjusted to
reduce the amount of signal being sent to
the audio buses. Also, the position of the
master level controls should be checked
to ensure that they are set correctly. In
most cases they should be set to the refer-
ence position, marked “U” for unity gain.
Technical Notes
Configuration Changes
Warning: A competent technician is
required to perform any configura-
tion review or changes. The cover of
the Model 742A must be removed
to access the configuration jump-
ers. This exposes the technician to a
potential shock hazard. Only after AC
mains power has been disconnected
and the mains cord removed from
the back of the Model 742A should
the cover be removed. If a DC source
is connected it should be removed
at this time also. Four screws, two on
each side of the chassis, are used to
secure the cover.