Studio Technologies 742 2005 - Manual (Page 23)

Model 742 User Guide Issue 2, May 2005
Studio Technologies, Inc. Page 23
Model 742
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 control 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 com-
pressors have been configured not to
operate (disabled) then obviously the
LEDs will never light. If the compressors
are enabled, typical operation should find
the LEDs lighting 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 reference 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 742 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 742, should
the cover be removed. Four screws,
two on each side of the chassis, are
used to secure the cover.
Phantom Power
The four mic/line inputs can be configured
to provide 12-volt phantom power, allow-
ing support for condenser microphones. If
phantom power is configured to be avail-
able, it will be present only when an input
sensitivity switch is set to its mic (out)
position. One configuration jumper is used
to select whether phantom power (for all
four mic/line inputs) is on or off. The fac-
tory default has the jumper set to the off
position. To enable phantom power, move
the jumper to the on position. Finding the
phantom power configuration location
takes a “keen eye.” When viewed with the
Model 742’s cover off, it is located near
the front of the printed circuit board, near
the input sensitivity (mic/line) switch as-
sociated with mic/line input 4. The jumper
section is labeled 12 V PHANTOM.