Studio Technologies 76D 2014 - Manual (Page 12)

Issue 11, May 2014 Model 76D/77 User Guide
Page 12 Studio Technologies, Inc.
for Surround
Pre-Fader Surround Monitor Output
The pre-fader surround monitor output
channels are intended to connect to meter-
ing, measurement, or other signal monitor-
ing equipment that requires uninterrupted,
full-level digital audio signal sources.
Stereo Input C Direct Monitor Output
The stereo input C direct monitor output
is intended for use in site-specific applica-
tions. It provides an uninterrupted, full-level
digital audio signal source that is post-SRC
and input delay in the signal chain.
Post-Fader Surround Monitor Output
The post-fader surround monitor output
channels are designed for connection to
digital inputs on audio amplifiers associat-
ed with monitor loudspeakers. Alternately,
they could be connected to the inputs of
loudspeakers that contain integrated am-
plifiers with digital audio input capability.
Post-Fader Stereo Monitor Output
The post-fader stereo monitor output
channels are intended to support a stereo
loudspeaker system, either by connecting
to the digital input of an amplifier associ-
ated with a set of loudspeakers or directly
to a set of amplified speakers that provide
digital inputs.
Sync Input
The Model 76D requires a timing reference
(sync) signal so that the digital audio input
and digital 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 dedicated
timing reference signal to the Model 76D’s
sync input connector. The connected sync
signal must maintain a stable relation-
ship 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 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 76D 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
connected to the sync input BNC connec-
tor located on the Model 76D’s back panel.
For flexibility this input can be configured