Studio Technologies 761 - Manual (Page 11)

Model 761/771 User Guide Issue 1, March 2008
Studio Technologies, Inc. Page 11
for Surround
276M standard. As expected, these signal
sources will be provided in the form of
coaxial cables with BNC plugs attached.
The Model 761 supports sampling rates
of up to 192 kHz with a word length (bit
depth) of up to 24. Note that no external
synchronization source is required as the
inputs are all self-clocking.
Balanced AES3 digital audio signals can
also be used with the Model 761’s inputs
so long as external coupling transformers
(“baluns”) are utilized. These impedance-
matching (110 ohms to 75 ohms) trans-
former assemblies typically use a 3-pin
female XLR connector on their input and
a female BNC connector on their output.
Monitor Outputs
The connector labeled Analog Monitor
Outputs provides access to the Model
761’s 5.1 surround and 2-channel stereo
director cue monitor outputs. The surround
output channels are intended to connect
to the main surround loudspeaker system
incorporated in a facility. The director
cue output channels are provided to
support a separate set of loudspeakers,
allowing monitoring of inter- or intra-facility
communications.
The monitor output channels are intended
for connection to audio amplifi ers associ-
ated with monitor loudspeakers, or to the
inputs of loudspeakers that contain inte-
grated amplifi ers. The monitor outputs are
electronically balanced and capable of
driving balanced or unbalanced loads of
600 ohms or greater. While balanced op-
eration is preferred, unbalanced operation
does not pose a problem. To connect to
an unbalanced load connect the + terminal
as signal high, and both the – and shield
as the signal low/shield. For optimal unbal-
anced operation, it is important to connect
both – and shield together directly on the
D-sub plug, not at the other end of the
harness.
Note that while the Model 761’s electroni-
cally balanced output circuits are capable
of driving loads of 600 ohms or greater,
the output level will drop slightly as the
load impedance approaches 600 ohms.
A 0.5 dB difference in output level can be
expected as the load impedance changes
from 10 k ohms to 600 ohms.
The wiring scheme used by the D-sub-
miniature connector complies with that
made popular by TASCAM® with their
DA-88® product. A wiring assembly pre-
pared for the Model 761’s monitor outputs
is identical to that of a DA-88-style output
assembly. Please refer to Figure 5 for the
exact connection details. Note that unlike
a DA-88-style assembly, the Model 761’s
D-sub connector uses 4-40 threads. This
complies with the original design standard
for D-subminiature connectors.
Signal Signal
Connections High (+) Low (–) Shield
L 24 12 25
R 10 23 11
C 21 9 22
LFE 7 20 8
LS 18 6 19
RS 4 17 5
Director Cue L 15 3 16
Director Cue R 1 14 2
Notes: 1) Connector type on Model 761 is 25-pin D-subminiature
female. Installer must provide plug (male). Connector uses
4-40 threaded inserts for locking with mating plug.
2) Wiring scheme follows TASCAM DA-88 convention.
Standard DA-88-type wiring harnesses are directly
compatible, with the exception of 4-40 screw threads
being required.
Figure 5. Connections for Monitor and Director
Cue Outputs