Studio Technologies 76DA V.4.12 - Manual (Page 13)

Model 76DA/77 User Guide Issue 9, May 2014
Studio Technologies, Inc. Page 13
for Surround
is identical to that of a DA-88-style out-
put 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. 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
the sample rate of the associated digital
audio sources. DARS (digital audio refer-
ence source) is a timing signal compliant
with the AES11 standard. It’s sometimes
referred to as “AES3-black.” Technically it is
similar to an AES3 signal but is generated
specifically as a timing reference signal.
Bi-level video sync signals were originally
provided to support NTSC and PAL broad-
cast applications, although they continue
to be used by contemporary equipment.
Tri-level sync signals were primarily asso-
ciated with facilities that supported high-
definition (HD) video equipment, however
the importance of this type of sync seems
to be waning. Both bi-level and tri-level
signals can be found at numerous rate
combinations, configured to allow for com-
patibility with the various video formats.
With the wide range of allowable sync
sources proper Model 76DA operation
should be easy to obtain. Extensive testing
has been done using many different sync
source types and rates. Interested users
can refer to Appendix B of this user guide
for details.
The external sync reference source is con-
nected to the sync input BNC connector
located on the Model 76DA’s back panel.
For flexibility this input can be configured
to be high-impedance (“floating”) or ter-
minated with an impedance of 75 ohms.
A sync source that is dedicated for use by
the Model 76DA’s sync input will typically
have input termination enabled. If the sync
Signal Signal
Connections High (+) Low (–) Shield
Surround L 24 12 25
Surround R 10 23 11
Surround C 21 9 22
Surround SUB 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 female
D-subminiature (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
Sync Input
The Model 76DA requires a timing refer-
ence (sync) signal so that the digital audio
input and digital monitor output signals will
be handled correctly. A configuration set-
ting 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