Studio Technologies 212 2006 - Manual (Page 12)

Issue 3, July 2006 Model 212 User Guide
Page 12 Studio Technologies, Inc.
headphone output. (51 ohm protection
resistors are electrically in series with the
headphone output circuits.) However en-
ergy will be wasted if an audio signal com-
ing out of the right channel goes into a
“dead short.” There is a simple solution to
this issue. No cue audio source should be
assigned to the right-channel headphone
output. Refer to the Configuration section
of this user guide for details.
AES3id Output
The main and talkback audio channels are
accessible by way of an AES3id digital au-
dio output. A BNC connector, located on
the back panel of the Model 212, provides
access to the transformer-coupled inter-
face. This type of digital audio interface
is commonly used for broadcast applica-
tions, providing a 75 ohm unbalanced im-
plementation of the AES 2-channel digital
audio standard. The Model 212’s interface
provides 24 bit audio signals with a default
sample rate of 48 kHz. The main output
audio signal will be present on channel 1
of the digital audio signal; talkback audio
will be present on channel 2.
Note that the clock source for the digital
audio output is derived from the selected
digital audio input. Should the input
source not be present the Model 212’s
internal clock source will automatically
be selected. The exception is when the
bidirectional digital interface is selected
as the input source. In this case a valid
signal must be connected to the bidirec-
tional digital interface for proper digital
audio output signals to be created; the
Model 212 is not be able use its internal
clock source.
The main output channel is intended to
be the “on-air” signal that connects to
an input channel of an audio console.
The talkback output channel is intended
for connection to control rooms, produc-
tion trailers, or other locations where
talent-originated voice cues are required.
The nominal level of the digital audio
signals is –20 dBFS. The actual levels
will depend on the gain setting of the
microphone preamplifier, sensitivity of the
microphone, how loudly the talent speaks
into the microphone, and the configuration
setting of the compressor threshold.
Talkback audio is also “on-air” quality,
which makes sense as the audio path
is shared by the talkback and main out-
put channels. Devices connected to the
talkback output channel can range from
amplifiers associated with loudspeakers to
inputs on digital matrix intercom systems.
Connecting the talkback output channel
to devices that allow easy control of the
signal level can be helpful. For example,
connecting to a spare input channel on
a digital audio console will provide the
resources to add gain or attenuation as
required. A talkback-associated output
path on the audio console can then con-
nect to the final destination(s).
Optional AES3 Output
Circuitry contained within the Model 212
allows a technician to add support for an
AES3 output. This type of interface allows
two channels of digital audio to be car-
ried over a balanced 110 ohm circuit. In
some Model 212 applications the AES3
output will be implemented using a 3-pin
male XLR-type connector installed in the
back panel. Other applications may use a
multi-pin connector, such as the Neutrik®
EtherCon® version of the 8-pin RJ45 jack.
Note that the signal coming out of the
AES3 output will be identical to that com-
ing out the Model 212’s AES3id output.