Studio Technologies 76DA V.3.01 - Manual (Page 19)

Model 76DA/77 User Guide Issue 2, April 2011
Studio Technologies, Inc. Page 19
for Surround
Sync Input Termination
The sync input circuitry can be configured
to terminate the signal connected to the
back-panel sync input BNC connector.
When termination is selected a 75 ohm
load is applied to the signal. When the
sync input is not terminated the input im-
pedance is very high, essentially applying
no load to the source. If the sync source
is connected only to the Model 76DA then
enabling termination is typically appropri-
ate. However, if the sync source is being
“shared” by multiple inputs then care must
be taken so that the signal is only termi-
nated by one device.
Audio-Synced-to-Video
Sample Rate
If a video sync signal is being used as the
Model 76DA’s timing reference the sample
rate of the connected digital audio sig-
nals must be specified. In most cases the
default value of 48 kHz will be appropriate,
but rates from 32 to 192 kHz are available.
Pre-Fader Surround/Stereo
Input C Direct Digital Monitor
Output Type
To meet the needs of specific installations
the nominal impedance and level char-
acteristic of the pre-fader surround and
stereo input C direct digital monitor outputs
can be selected. They are selected as
a group; configuration of individual digital
outputs is not provided. If the digital output
signals are going to be connected to
balanced AES3 inputs then the setting
that provides a source impedance of
110 ohms and a nominal 5 Vpp output
level would be appropriate. If the digital
output signals are going to be connected
to unbalanced AES3id inputs then the
setting that provides a 75 ohm source
impedance and a nominal output level
of 1 Vpp would be correct.
Post-Fader Surround/Stereo
Digital Monitor Output Type
The source impedance and output level of
the post-fader surround and stereo digital
monitor outputs, as a group, can be config-
ured. The information previously provided
concerning configuring the pre-fader sur-
round/stereo input C direct digital monitor
output type also applies to these outputs.
Reference Level
For audio-with-picture applications it’s
often beneficial for monitoring to be done
in reference to a known loudspeaker
level. This is often referred to as “mixing
to 85 dB” on the monitors. The Studio-
Comm for Surround system allows a
precise post-fader surround digital and
analog monitor output level to be stored,
and then enabled by pressing the Model
77 button labeled Reference Level. Setting
the reference level is very simple but care
is required:
1. Set up a precision sound pressure
level (SPL) measuring device at the
desired listening location.
2. Place the StudioComm system in the
normal operating mode, not the config-
uration mode. Be certain that the dim,
mute all, reference level, and downmix
functions are not active. The remote
mute all and remote dim functions
must also not be active.
3. Use the Model 77 Control Console to
select the input source that contains
the desired reference signal source,
e.g., pink noise.