Studio Technologies 42A 2008 - Manual (Page 13)

Model 42A User Guide Issue 2, February 2008
Studio Technologies, Inc. Page 13
The wire colors in the mains cord must
conform to the internationally recognized
color code and should be terminated
accordingly:
Connection Wire Color
Neutral (N) Light Blue
Line (L) Brown
Earth/Ground (E) Green/Yellow
Safety Warning: The Model 42A does
not contain an AC mains disconnect
switch. As such, the AC mains cord
plug serves as the disconnection de-
vice. Safety considerations require that
the plug and associated inlet be easily
accessible to allow rapid disconnec-
tion of AC mains power should it prove
necessary.
As soon as AC mains power is applied
the Model 42A will begin its power-up
sequence. As a “boot up” indication each
of the monitor section’s status LEDs will
light in an ascending order. After that has
completed one of the status LEDs will
remain lit. The unit is now fully functional.
Post-Installation
Audio Input Source Level
Adjustment
It’s important to confirm and, if required,
adjust the level of the audio sources that
are connected to the Model 42A’s inputs.
The monitor section’s dual 5-segment
LED level meters will help make this
task simple. Begin by using the push-
button switch, located on the front panel,
to select the IFB circuit that is going to be
calibrated. Adjust the source levels so that
the green LEDs light when typical audio
signals are present. The desired nominal
output level of the IFB circuits is –10 dBu.
This is reflected in the top green LED
being calibrated to, and labeled, –10. The
meters’ yellow LEDs, labeled –4, should
light infrequently, generally only when sig-
nal peaks are present. Achieving a precise
level calibration is not critical. But getting
the levels within the optimum range is very
important!
It’s likely that the initial levels provided by
analog ports on a digital matrix intercom
system won’t be an exact match with the
Model 42A’s inputs. This shouldn’t pose a
problem as the computer control available
on contemporary intercom systems should
make level adjustment very simple. From
our research we found that the Clear-Com
Eclipse™ system specifies a nominal level
of 0 dBu. Since their headroom is listed as
greater than 18 dB, increasing the nominal
level of their analog output ports by 4 dB
(to achieve the desired +4 dBu) should
be acceptable. RTS in their ADAM™ and
ZEUS™ systems specify nominal output
levels of +8 dBu. With these systems cor-
rect Model 42A performance would be
provided by
reducing the ports’ output levels by 4 dB.
With the Artist™ system from Riedel,
the analog ports have a nominal level of
+6 dBu. A 2 dB reduction in their output
level would be beneficial. In reality, a signal
with a nominal level that deviates some-
what from precisely +4 dBu will be accept-
able. But with the power of contemporary
computer-controlled intercom systems,
there’s no reason why a precisely calibrat-
ed system can’t be easily implemented.
Audio Integrity
At this stage the Model 42A should have
been installed and the levels of the input