Studio Technologies 76DBA V.3.00 - Manual (Page 38)

Issue 1, November 2010 Model 76DBA/77B User Guide
Page 38 Studio Technologies, Inc.
for Surround
between groups will switch between two
specific inputs. This allows rapid switching
between, for example, input 1 and input 6.
The specific sources assigned to the input
buttons depend on the signals connected
to the Model 76DBA along with how the
system has been configured. Any input
can be assigned to any input select but-
ton. (Technically, the same input could be
assigned to multiple buttons!) This means,
for example, that a surround input could be
monitored using any of the input select but-
tons. The same holds true for a stereo, dual
channel, or monaural input source.
Downmix
Two downmix functions allow users to
perform “real-world” audio format com-
patibility checks. One function allows a
surround (5.1) signal to be “folded down”
(mixed) to stereo. The other allows a stereo
signal to be converted to mono. Using the
downmix functions simply requires press-
ing the desired button. The buttons are set
to always “latch” the functions on and off.
An LED is located adjacent to each button
and lights whenever its respective function
is active. The downmix functions always
impact the post-fader surround digital and
analog monitor outputs. And, depending on
the selected configuration, they may also
impact the pre-fader surround digital moni-
tor output. Please refer to the Specifications
section of this guide if you’d like a detailed
description of how the downmix functions
perform their tasks.
A specific downmix function can only be
enabled when it is applicable for the cur-
rently selected input source. This means
that the 5.1 to stereo downmix function can
only be enabled when surround input A or B
is selected.
The Model 77B associates the state of
the downmix functions with the currently
selected input. For example, if surround
input A is the selected input source and
the 5.1 to stereo downmix function is en-
abled, this condition will be “remembered”
when switching to one of the stereo input
sources. Upon returning to surround input
A, the 5.1 to stereo downmix function will
again become active.
5.1 to Stereo
When the 5.1 to stereo downmix function
is enabled the LS, RS, and C channels
associated with a surround source are
combined (“folded down”) with the L and
R signals to create a 2-channel stereo (left
and right) signal. And, depending on the
system’s configuration, the LFE channel
may also be combined with the L and R
signals. The resulting stereo signal, some-
times known as LoRo, is routed to the L
and R surround digital and analog monitor
output channels. The C, LFE, LS, and RS
digital and analog monitor output channels
are muted. By utilizing this downmix func-
tion phase relationships and inter-channel
level issues can be quickly observed.
Stereo to Mono
The stereo to mono downmix function
combines the L and R audio channels to
create a single-channel monaural signal.
This signal is sent out the C surround
digital and analog monitor output channels
while the L, R, LS, RS, and LFE digital and
analog monitor output channels are muted.
When a surround source has been
selected for monitoring, the 5.1 to stereo
downmix function will automatically enable
whenever the stereo to mono downmix
function is enabled. This ensures that an
operator will hear a mono signal created