Studio Technologies 76DA V.3.01 - Manual (Page 12)

Issue 2, April 2011 Model 76DA/77 User Guide
Page 12 Studio Technologies, Inc.
for Surround
2-channel stereo analog monitor outputs.
The surround analog monitor output chan-
nels are intended to connect to analog
inputs associated with the surround loud-
speaker system incorporated in a facility.
The stereo analog monitor output allows
support for a secondary set of stereo moni-
tor loudspeakers.
The analog monitor output channels are
designed for connection to audio amplifiers
associated with monitor loudspeakers or
to the inputs of loudspeakers that contain
integrated amplifiers. The analog monitor
outputs are electronically balanced and will
perform optimally when driving loads of
2000 (2 k) ohms or greater. In most applica-
tions 3-pin XLR plugs (male) will be used
to interface with the inputs on the associ-
ated amplifiers or amplified speakers. 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.
Balanced operation of the analog monitor
outputs is the preferred connection method
but unbalanced operation does not pose a
problem. To connect to an unbalanced load
connect the + terminal as signal high, and
only the Model 76DA’s shield terminal as
the signal low/shield. Leave the – terminal
unconnected. For correct unbalanced
operation, it is important not to connect
– and shield together.
The wiring scheme used by the D-submin-
iature connector complies with that made
popular by TASCAM® with their DA-88®
product. A wiring assembly prepared for
the Model 76DA’s analog monitor outputs
is identical to that of a DA-88-style output
assembly. Please refer to Figure 5 for the
exact connection details. Again note that
unlike a DA-88-style assembly, the Model
76DA’s D-sub connectors use 4-40 threads.
Sync Input
The Model 76DA requires a timing refer-
ence (sync) signal so that the digital audio
input and monitor output signals will be
handled correctly. A configuration setting
allows the source of sync to be the L/R
input of the currently selected surround
or stereo digital audio input. While this is
acceptable, audio artifacts (clicks or noise)
can occur when switching between inputs.
A better method is to connect a dedi-
cated timing reference signal to the Model
76DA’s sync input connector. The con-
nected sync signal must maintain a stable
relationship between itself and the digital
audio inputs. The actual sync source can
be in one of several formats: word clock,
DARS (AES11), bi-level video, or tri-level
video.
An overview of the various compatible
timing reference signals might prove
worthwhile. Word clock is a digital signal
that is locked in phase and frequency to
Signal Signal
Connections High (+) Low (–) Shield
Surround L 24 12 25
Surround R 10 23 11
Surround C 21 9 22
Surround LFE 7 20 8
Surround LS 18 6 19
Surround RS 4 17 5
Stereo L 15 3 16
Stereo R 1 14 2
Notes: 1) Connector type on Model 76DA is 25-pin
D-subminiature female (DB-25F). Installer must provide
male (DB-25M). 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 Analog Monitor
Outputs