Studio Technologies 76DBA V.3.00 - Manual (Page 14)

Issue 1, November 2010 Model 76DBA/77B User Guide
Page 14 Studio Technologies, Inc.
for Surround
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 76DBA’s analog monitor outputs
is identical to that of a DA-88-style output
assembly. Please refer to Figure 5 or
Appendix A for the exact connection de-
tails. Again note that unlike a DA-88-style
assembly, the Model 76DBA’s D-sub
connectors use 4-40 threads. dedicated timing reference signal to the
Model 76DBA’s sync input connector. The
connected 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
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 or AES3id signal but
is generated specifically as a timing refer-
ence signal. Bi-level video sync signals
were originally provided to support NTSC
and PAL broadcast applications, although
they continue to be used by contempo-
rary equipment. Tri-level sync signals
were primarily associated 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 compatibility with the various
video formats.
With the wide range of allowable sync
sources proper Model 76DBA 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 76DBA’s back panel.
Sync Input
The Model 76DBA 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 sur-
round 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
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
Auxiliary Stereo L 15 3 16
Auxiliary Stereo R 1 14 2
Notes: 1) Connector type on Model 76DBA 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