Studio Technologies 76DA V.3.01 - Manual (Page 9)

Model 76DA/77 User Guide Issue 2, April 2011
Studio Technologies, Inc. Page 9
for Surround
Mounting the Model 76DA
The Model 76DA Central Controller
requires one space (1U) in a standard
19-inch (48.3 cm) equipment rack. Secure
the Model 76DA into the equipment rack
using two mounting screws per side.
Select a location that is convenient for
making connections to the audio signals
as well as interfacing with the first (or only)
Model 77 Control Console. A cable is sup-
plied to connect the Model 76DA to the
Model 77. If the needs of a specific instal-
lation dictate, an alternate-length intercon-
necting cable can be fabricated and used.
Audio Connections
Audio connections are made by way of
nine BNC jacks and two 25-pin D-submin-
iature connectors. All the connectors are
located on the Model 76DA’s back panel.
Refer to Figure 2 for a detailed view of
these jacks and the connector.
Digital Audio Inputs
Two surround (5.1) and three stereo digital
audio sources can be connected. All sourc-
es can be monitored using the pre- and
post-fader surround and post-fader stereo
digital and analog monitor output channels.
A one-to-one relationship is maintained
between the input and output channels,
i.e., left input to left monitor output, right
input to right monitor output, center input
to center monitor output, etc. (Of course
this won’t be true in the case where the
user has enabled one or both of the down-
mix function.) Stereo input C is also routed
to the stereo input C direct digital monitor
output.
The digital audio inputs support digital
audio signals with a sampling rate of up to
192 kHz and a word length (depth) of up
to 24 bits. It’s best if the connected signal
sources maintain a common sample rate
and timing reference. Having all signals
“locked” together helps to ensure proper
handling by the Model 76DA’s all-digital
signal control path.
There is, however, an exception worth
noting. Circuitry associated with stereo
input C has sample rate conversion (SRC)
capability, allowing virtually any digital
audio signal to be connected. A signal
connected to stereo input C can have an
independent sample rate and timing refer-
ence and still be monitored correctly. Refer
to the Technical Notes section of this guide
for a detailed review of the SRC capability.
Nine BNC jacks on the Model 76DA’s back
panel are used to interface with the 18
channels associated with the digital audio
signal sources; each BNC connector car-
ries two audio channels. The digital audio
inputs are intended for connection with
unbalanced digital audio sources that are
compatible with the AES3id standard. In
broadcast or post-production environments
these signals may also be referred to as
following the SMPTE 276M standard. This
signal type has a nominal impedance of
75 ohms with a nominal signal level of
1 Vpp. As expected, these digital audio
sources should be provided in the form of
coaxial cables with BNC plugs attached.
Balanced AES3 digital audio signals can
also be used with the Model 76DA’s inputs
if external coupling transformers (“baluns”)
are utilized. These impedance-matching
(110 ohms to 75 ohms) and level-attenuat-
ing transformer assemblies typically pro-
vide a 3-pin female XLR connector on their
input and a female BNC connector on their
output.