Studio Technologies 76DA V.4.12 - Manual (Page 11)

Model 76DA/77 User Guide Issue 9, May 2014
Studio Technologies, Inc. Page 11
for Surround
XLR connectors. When a group is config-
ured for unbalanced AES3 operation the
signals have a nominal impedance of 75
ohms and a nominal level of 1 Vpp. These
signals are typically interconnected using
coaxial cable terminated with BNC connec-
tors. For details on how a Model 77 Control
Console is used to select the digital moni-
tor output types refer to the Configuration
section of this user guide.
A cable assembly with a 25-pin male D-
sub connector (DB-25M) on one end and
the desired connectors on the other end
will be used for connecting to the digital
monitor outputs. The D-subminiature con-
nector follows the TASCAM® wiring con-
vention, organizing the 25 pins into eight
groups of three pins each; one pin remains
unused. Each set of three pins provides an
independent interface. In the analog world
this would allow eight audio signals to be
transported. But with AES3 digital audio
signals this allows support for 16 audio
channels; eight interfaces each supplying
two audio channels.
A wiring assembly prepared for the Model
76DA’s digital monitor outputs, when con-
figured for balanced AES3 (110 ohms/
5 Vpp), would be identical to that of a DA-
88-style output assembly. An assembly
of this type would have a 25-pin male D-
subminiature connector (DB-25M) on one
end and eight 3-pin male XLR connectors
on the other. A wiring assembly prepared
for the Model 76DA’s digital monitor out-
puts, when set for unbalanced AES3
(75 ohms/1 Vpp), would typically have
eight BNC plugs attached.
For compatibility with balanced AES3
digital audio signals connect the D-sub’s +
terminal as signal high and the – terminal
as signal low. In most applications a 3-pin
male XLR connector will be used. In this
case the + terminal would go to pin 2 of the
XLR, the – terminal to XLR pin 3, and the
shield terminal to XLR pin 1.
For compatibility with unbalanced AES3
digital audio signals connect the D-sub’s
+ terminal as signal high, and both the
– and shield terminals as the signal low/
shield. When terminating to a BNC plug the
D-sub’s + terminal should connect to the
center pin; the – and the shield connec-
tions should go to the “body” of the BNC
plug. To clarify, for optimal operation it is
best to connect both the – and shield con-
nectors together directly on the D-sub plug,
rather than at the BNC end of the interface
assembly. Note that the output circuitry is
transformer-coupled so it is possible to just
connect to the + and – terminals and still ex-
perience correct operation. This would leave
the shield connection unterminated.
Refer to Figure 4 or Appendix A for the
exact connection details. Note that unlike
a DA-88-style assembly, the two threaded
fasteners associated with the Model 76DA’s
D-sub connectors use 4-40 threads. This
complies with the original design standard
for D-subminiature connectors.
Pre-Fader Surround Digital Monitor
Output
The pre-fader surround digital monitor
output channels are intended to connect
to metering, measurement, or other
signal monitoring equipment that requires
uninterrupted, full-level digital audio signal
sources.
Stereo Input C Direct Digital Monitor
Output
The stereo input C direct digital monitor
output is intended for use in site-specific
applications. It provides an uninterrupted,