Studio Technologies 76B 2008 - Manual (Page 17)

Model 76B/77B User Guide Issue 1, July 2008
Studio Technologies, Inc. Page 17
for Surround
toward achieving optimal audio perfor-
mance. This ensures that the Model 76B’s
digital audio receiver integrated circuits
are confi gured to match the digital input
source’s “0 VU” or average point. The digi-
tal input reference level can be selected
from four choices: –20.0, –18.0, –16.0,
and –14.0 dBFS. Note that this parameter
sets, as a group, the input reference level
for all of the Model 76B’s digital input con-
nections. The Society of Motion Picture
and Television Engineers (SMPTE) rec-
ommends a reference level of –20 dBFS,
a value which is also extensively used
in professional audio applications. The
recommended digital reference level for
PAL broadcast applications is –18 dBFS.
The other two levels were included be-
cause… well, we can’t remember why! But
it seemed like a good idea at the time. If
you end up using the –16.0 or –14.0 dBFS
settings please let us know why and we’ll
add that information to the next version of
this user guide!
Monitor Output Nominal Level
The nominal level of the six channels
associated with the surround (5.1) output
are confi gured, as a group, to match the
requirements of an installation. This setting
defi nes the analog output level when
a digital input source, at its reference level,
is connected and the monitor output level
is at its maximum. The choices are 0.0 or
+4.0 dBu. Most applications will fi nd the
+4.0 dBu setting correct as it meets the
dominant worldwide audio standards.
For broadcast applications that follow
the PAL standards the 0.0 dBu setting
may be appropriate.
A fi nal review of the two previously se-
lected settings might now be in order. The
most common input and output combina-
tion will have a digital input reference level
of –20.0 dBFS and a monitor output nomi-
nal level of +4.0 dBu. For PAL broadcast
applications a setting of –18.0 dBFS for
the digital input and 0.0 dBu for the analog
outputs would be typical.
Input Select Buttons
The three input select buttons, along with
the group select button, allow six source
confi gurations to be selected for monitor-
ing. The Model 76B has connections
for two surround (5.1) and three stereo
(2-channel) AES3id digital audio sources.
Any of these sources can be assigned
to any of the input select buttons. To fi t
broadcast applications where it’s typical
for non-stereo pairs to share an AES3id
2-channel path, the individual left and right
audio channels of stereo inputs A and B
can be assigned to separate input select
buttons as required. These “mono” signals
will be routed to the center monitor output
channel.
Spending time reviewing the input select
button confi guration function may prove
very worthwhile. It is a unique feature of
the StudioComm for Surround system
and offers a great opportunity to optimize
monitoring performance.
Reference Level
For audio-with-picture applications it’s
often benefi cial 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 StudioComm for
Surround system allows a precise monitor
output level to be stored, and then enabled