Studio Technologies 212 2013 - Manual (Page 6)

Issue 5, May 2013 Model 212 User Guide
Page 6 Studio Technologies, Inc.
A truly next-generation product, extensive
research into the needs and desires of
field production personnel was integral to
the Model 212’s creation. While primarily
targeted for on-air television applications,
specialized features are included to allow
the Model 212 to be used in a variety of
other audio applications. These include
on-air radio broadcasting, stadium an-
nouncement, live production, and voice-
over/narration booths.
System Features
Microphone Input
A high-performance microphone pre-
amplifier circuit provides low-noise/
low-distortion amplification over a 10 to
50 dB gain range. The gain is adjustable
in 10 dB steps. The input is compatible
with balanced dynamic or condenser
microphones. The microphone power
source is 48 volts nominal and meets the
worldwide P48 phantom standard. An LED
indicator serves as an aid for optimizing
the setting of the preamplifier’s gain. The
output of the microphone preamplifier
is routed to the compressor circuit that
supports the main and talkback audio
channels.
Dynamic Range Control
A studio-quality compressor circuit is
provided to control the dynamic range
of the analog signal coming from the
microphone preamplifier. Far from a
simple “clipper,” the circuit utilizes a
sophisticated laser-trimmed voltage-
controlled-amplifier (VCA) integrated cir-
cuit for quiet, low-distortion level control.
The output of the compressor is used by
the main and talkback channels, being
routed to the inputs of their respective
analog-to-digital converter circuits. The
threshold of the compressor can be con-
figured from among two values. With the
compressor configured to –14 dBFS some
dynamic range control would be expected
during normal operation. While possibly
inappropriate for major on-air situations,
having dynamic range control of the
signal can offer increased performance
for many applications. This would be ap-
propriate for applications such as stadium
announcement positions, sports events
using nonprofessional on-air talent, as
well as situations where the risk of digital
“clipping” is present. When configured
for –4 dBFS, dynamic range control will
only take place as the signal approaches
the level limit of the digital signal. During
normal operation the compressor would
not be active.
Main and Talkback Audio
Channels
Internally, the Model 212 creates analog
main and talkback audio channels. The
main audio channel is designed to serve
as the on-air, stadium announcement, or
other primary audio feed. The talkback
audio channel is intended to provide
production trucks, control rooms, or sup-
port personnel with a talent-originated
cue signal. The two analog channels are
converted to 24-bit PCM digital audio and
multiplexed and formatted into an AES
digital audio “stream.” The A/D converters
and digital transmitter circuitry is synchro-
nized (“locked”) to the selected digital
input signal. If that signal Is not present
the Model 212 will automatically revert to
an internal clock which provides a 48 kHz
sampling rate. The main audio channel is
assigned to digital channel 1 with talkback