Studio Technologies 210 2012 - Manual (Page 27)

Model 210 User Guide Issue 5, September 2012
Studio Technologies, Inc. Page 27
of most IFB systems, such as the RTS
4000-series. But actually having the cor-
rect level present on an IFB circuit is often
a “hit-or-miss” proposition. During field
testing of prototype announcer’s consoles,
Studio Technologies’ personnel found that
a wide range of nominal audio levels were
present on “real-world” IFB circuits. Many
were fine, being reasonably close to the
desired –10 dBu. But some were much too
low, while others were much too “hot.” We
observed one unfortunate baseball “color”
commentator being sent interrupt audio
signals so “hot” relative to program audio
as to almost make his ears bleed! This
situation should not have been allowed
to happen.
In defense of field technical personnel,
measuring the audio level of an IFB circuit
hasn’t traditionally been an easy proposi-
tion. But that situation has now changed.
After experiencing this condition in the
“field,” Studio Technologies’ engineers
were motivated to design the Model 72
Level Meter/Interface. This compact
device plugs directly into IFB and intercom
circuits and provides two useful functions:
level meters and “dry” audio outputs. Two
5-segment LED meters allow direct obser-
vation of the audio signal levels present on
IFB or intercom circuits. The display range
is optimized for the signal levels found on
these circuits, rather than traditional “VU”
scaling.
The Model 72 also provides two trans-
former-coupled “dry” audio outputs, one
for each IFB or intercom channel. These
outputs are useful for a variety of produc-
tion and testing applications. For example,
the outputs can serve as the interface
between a traditional “wet” IFB system
and a wireless in-ear monitor system. The
outputs can also be connected to a moni-
tor panel, allowing visual and aural moni-
toring of the IFB audio signals.
In conclusion, we’re sorry for this shame-
less promotion of the Model 72 Level
Meter/Interface! But necessity was defi-
nitely the “mother” when it came to the
unit’s invention. Working in the field
without such a device, we felt “blind” when
connecting to IFB circuits. That no longer
has to be the case and we think that you’ll
find owning one a very worthwhile invest-
ment. For further information please refer
to the Studio Technologies website.
Phantom Power
The Model 210 provides a 48 volt nominal
source of phantom power to support con-
denser-type microphones. It’s designed
to meet the P48 requirements as specified
in the IEC 61938 standard. The circuitry is
very simple: two 6.81 k ohm resistors pro-
vide a path from a 48 volt source to pins 2
and 3 of the microphone input connector.
The resistors and the power source work
together to provide 48 ±4 volts, up to a
maximum current of 10 milliamperes.
Symptoms of Insufficient
Power
A core part of the Model 210’s internal
circuitry is a switch-mode power supply
that produces +48 volts, +12 volts,
+5 volts, and –12 volts. This power supply
circuit works very well as long as it is “fed”
with sufficient input voltage and current.
“Sufficient” is defined as a minimum of
24 volts on the IFB input and 20 volts on
the external 24 volt DC input. The neces-
sary current, 105 milliamperes for the IFB
input and 70 milliamperes for the external
input, must be supplied over their respec-
tive voltage ranges.