Studio Technologies 41 2007 - Manual (Page 13)

Model 41 User Guide Issue 2, February 2007
Studio Technologies, Inc. Page 13
the Clear-Com Eclipse™ system speci-
fies a nominal level of 0 dBu. Since their
headroom is listed as greater than 18 dB,
increasing the nominal level of their ana-
log 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 correct Model 41
performance would be provided by reduc-
ing 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 somewhat from
precisely +4 dBu will be acceptable. But
with the power of contemporary computer-
controlled intercom systems, there’s no
reason why a precisely calibrated system
can’t be easily implemented.
Audio Integrity
At this stage the Model 41 should have
been installed and the input levels ad-
justed as required. The unit should now
be ready for many years of excellent per-
formance. But before turning to another
task, performing a final Model 41 “reality
check” is highly recommended. Using
the monitor section, along with a pair of
high-quality stereo headphones, carefully
listen to each channel associated with the
four IFB circuits. Ensure that the correct
audio sources are assigned to the cor-
rect IFB circuits. Confirm that all interrupt
channels have the correct audio levels as
they switch from normal audio to interrupt
content. Overall, the audio quality should
be excellent, with no hum, noise, hiss, or
other objectionable content. Should any
issues be detected, now is the time to
work them out. Presenting IFB circuit us-
ers with a correctly implemented system
will make life better for everyone involved!
Operation
Overall, the Model 41 is designed for con-
tinuous operation with no adjustment or
maintenance required. On the input side,
maintaining the correct level coming from
the audio sources is very important. As for
the IFB outputs, the cabling that connects
the Model 41 to the user devices must
remain free of full or partial short circuits.
And the total current draw of the con-
nected user devices must remain at 200
milliamperes or less.
The audio and DC voltage monitor func-
tions will assist users in confirming that
correct operation is taking place. In addi-
tion, the under-voltage shutdown function
will help to protect the IFB output circuitry
and connected user devices should a fault
condition be detected. The “heart” of the
monitor section is logic circuitry created
by a microcontroller integrated circuit
along with its associated firmware. This
combination adds “smarts” to otherwise
fairly pedestrian functions.
Using four electromechanical relays, the
audio monitor section accesses the IFB
circuits directly on pins 2 and 3 of the
output connectors. This ensures that the
impact of the actual wiring and connected
user devices is monitored, rather than just
observing something internal to the Model
41’s circuitry. Pin 2 of each of the four
IFB output connectors is also connected,
by way of interface circuitry, to analog-to-
digital converter inputs on the processor.
This allows the DC output voltages to be
continuously monitored.