Studio Technologies 212 2013 - Manual (Page 12)

Issue 5, May 2013 Model 212 User Guide
Page 12 Studio Technologies, Inc.
jack. The right channel is connected to the
“ring” lead of the jack. Common for both
channels is connected to the “sleeve”
lead.
Devices with ¼-inch 2-conductor “mono”
plugs can also be used with the Model
212’s headphone output. In this arrange-
ment only the tip lead (left channel) will
be active. The 2-conductor plug will
physically connect (“short”) the ring lead
(right channel) to the sleeve lead (com-
mon). Technically this won’t damage the
circuitry associated with the right-channel
headphone output. (50 ohm protection
resistors are electrically in series with the
headphone output circuits.) However,
energy will be wasted if an audio signal
coming out of the right channel goes into
a “dead short.” There is a simple solution
to this issue. No audio source should be
assigned to the right-channel headphone
output. Refer to the Configuration section
of this user guide for details.
Unbalanced Digital Audio
Output
The main and talkback audio channels
are accessible by way of an AES3id unbal-
anced digital audio output. A BNC con-
nector, located on the back panel of the
Model 212, provides access to the trans-
former-coupled interface. This type
of digital audio interface is commonly
used for broadcast applications, providing
a 75 ohm unbalanced implementation 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 pres-
ent on channel 2.
The clock (timing) 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; in this
configuration the Model 212 will 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, production
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 mi-
crophone, and the configuration setting
of the compressor threshold.
Talkback audio is also “on-air” quality,
which makes sense since 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 ex-
ample, connecting to a spare input chan-
nel on a digital audio console will provide
the resources to add gain or attenuate the
signal as required. A talkback-associated
output path on the audio console can then
connect to the final destination(s).