Datasheet

Studio Technologies, Inc. Model 381 On-Air Beltpack, Issue 1, Page 2
monaural headset, or even a monaural earpiece are connected
to the headphone output jack. Two “push-in/push-out” rotary
controls (potentiometers or “pots”) make it easy to set the
level of the talent cue signals level being sent to the 2-channel
headphone output.
The STcontroller software application is used to configure the
wide range of Model 381 operating parameters. This allows
the unit’s performance to be optimized to meet the needs of
specific applications. The Model 381’s ultra-compact enclo
-
sure is made from an aluminum alloy which offers both light
weight and ruggedness. A stainless steel “belt clip,” located
on the back of the unit, allows direct attachment to a user’s
clothing. The top surface is curved to minimize the chance of
the unit interfering with clothing or being readily observable
“on camera.”
Ethernet Data and PoE
The Model 381 connects to a local area network (LAN) by
way of a standard 100 Mb/s twisted-pair Ethernet interface.
The physical 100BASE-TX interconnection is made by way of
a Neutrik® etherCON RJ45 connector. While compatible with
standard RJ45 plugs, etherCON allows a ruggedized and lock-
ing interconnection for harsh or high-reliability environments.
The Model 381’s operating power is provided by way of the
Ethernet interface using the 802.3af Power-over-Ethernet (PoE)
standard. This allows fast and efficient interconnection with
the associated data network. To support PoE power manage
-
ment, the Model 381’s PoE interface enumerates (reports) to
the power sourcing equipment (PSE) that it’s a class 2 (low
power) device.
Dante Audio-over-Ethernet
Audio data is sent to and received from the Model 381 using
the Dante audio-over-Ethernet media networking technology.
The Model 381’s two Dante output (transmitter) and two Dante
input (receiver) audio channels can be assigned to other devices
(routed) using the Dante Controller software application. The
Dante transmitter and receiver channels are limited to support
-
ing four Dante flows, two in each direction. The digital audio’s
bit depth is up to 24 with a sampling rate of 44.1, 48, 88.2, or
96 kHz. Two bi-color LEDs provide an indication of the Dante
connection status.
The Model 381 is compatible with the AES67 interoperability
standard. In this mode the two transmitter (output) channels
will function in multicast; unicast is not supported. In addition,
the unit is compatible with the Dante Domain Manager (DDM)
software application.
Audio Quality
The Model 381’s performance is completely “pro,” making it
appropriate for use in a wide-range of applications. A low-noise,
wide dynamic-range microphone preamplifier and associ
-
ated voltage-controlled-amplifier (VCA) dynamics controller
(“compressor”) circuit ensures that mic input audio quality is
preserved while minimizing the chance of signal overload. A
configuration choice allows selection of the signal source for the
Dante main output channel. The choices are either the output of
the microphone preamp or the output of the compressor circuit.
These choices are referred to as “pre-compressor” or “post-
compressor.” The ADC section utilizes a high-performance
integrated circuit that supports sampling rates of 44.1, 48, 88.2,
and 96 kHz with a bit depth of up to 24. The audio signal, now
in the digital domain, routes through a 32-bit microprocessor
and on to the Dante interface section where it is packetized
and prepared for transport over Ethernet.
Audio input signals arrive via the Dante receiver channels and
pass into the Model 381’s microprocessor. As with the Dante
audio output channels, the sampling rate can be 44.1, 48,
88.2, or 96 kHz with a bit depth of up to 24. Channel routing,
headphone level control, and sidetone creation are performed
in the digital domain. This provides flexibility, allows precise
control, and keeps the two controls from having to directly
handle analog audio signals. The audio channels destined for
the headphone output channels are sent to a high-performance
digital-to-analog converter and then on to robust driver circuit
-
ry. High signal levels can be provided to a variety of headsets,
headphones, and earpieces.
Configuration Flexibility
The Model 381 can be configured to meet the needs of specific
applications and user preferences. All configuration tasks are
performed using the STcontroller personal computer software
application which is compatible with version 7 and later of the
Windows® operating systems. There are no mechanical switch
settings or button-press sequences required to configure how
the unit functions. Selectable parameters include microphone
preamplifier gain, P48 phantom power on/off, headphone
output performance, sidetone operation, talkback button
operation, and main output audio source.
The gain of the microphone preamplifier can be selected
from among five choices. This allows the Model 381 to match
the output sensitivity of a range of handheld and headset-asso
-
ciated microphones. A low-noise source of P48 phantom power
can be enabled if required to support condenser (capacitor)
microphones. The two Dante input audio sources and the way