Studio Technologies 76DA V.3.01 - Manual (Page 13)

Model 76DA/77 User Guide Issue 2, April 2011
Studio Technologies, Inc. Page 13
for Surround
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 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 connected to the Model 76DA is be-
ing connected (“multed”) to other inputs it
may be desirable for the termination to be
disabled. A general “rule of thumb” is that
termination should be applied only at the
location of the last physical device using a
sync signal.
Remote Control Inputs
Support is provided for two remote con-
trol input functions: remote mute all and
remote dim. These functions only impact
the post-fader surround and stereo digital
and analog monitor outputs. The Model
76DA’s inputs use logic gates, “pulled up”
to +5 volts DC by way of resistors, which
are active whenever they are brought to
their logic low state. Inputs of this type are
commonly referred to as GPI inputs. While
the input circuitry is protected from over-
current and static discharge (ESD), care
should be taken to prevent nasty signals
from reaching them. The inputs are active
only when held in the low state; they can’t
be configured to change state (“latch”) in
response to a logic pulse.
A 9-pin D-subminiature connector is used
for the remote control inputs. Refer to
Figure 6 or Appendix A for the exact con-
nection details. Note that pin 4 (remote
common) connects to the Model 76DA’s
internal circuit common connection as well
as to the Model 76DA’s chassis and mains
earth connections. Figure 6 also shows
two spare remote control inputs (pins 8
Signal Pin Direction
Data + (RS-485/RS-422) 7 Not used
Data – (RS-485/RS-422) 2 Not used
Data Shield 1 Shield
Remote Mute All 5 Input
Remote Dim 6 Input
Remote Spare 1 8 Input
Remote Spare 2 9 Input
Remote Common 4 Common
Note: Connector type on Model 76DA is 9-pin D-subminiature
female (DE-9F). Connector uses 4-40 threaded inserts
for locking with mating plug.
Figure 6. Connections for Remote Control
Inputs