Studio Technologies 41 2013 - Manual (Page 13)

Model 41 User Guide Issue 3, November 2013
Studio Technologies, Inc. Page 13
system from Riedel, the analog ports have
a nominal level of +6 dBu. A 2 dB reduc-
tion in their output level would be benefi-
cial. In reality, a signal with a nominal
level that deviates somewhat from pre-
cisely +4 dBu will be acceptable. But with
the flexibility 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 audio source levels
adjusted 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 outputs. Ensure that the correct
audio sources are assigned to the cor-
rect IFB outputs. 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
correct them. Presenting users with a cor-
rectly implemented IFB 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 audio 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
connected user devices must remain at
220 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
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
outputs directly on pins 2 and 3 of their
respective output connector. This ensures
that the impact of the actual wiring and
connected user devices is monitored, rath-
er 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 volt-
ages to be continuously monitored.
Associated with the audio and DC voltage
monitor functions are four status LEDs,
one pushbutton switch, two 5-segment
LED level meters, a rotary level control,
and a headphone jack. The four monitor
status LEDs are used to indicate which
IFB output is currently being audio moni-
tored as well as presenting the status of
the DC output voltages. One of the LEDs
is always lit, indicating which IFB output is
currently being monitored by the meters
and headphone output.