Studio Technologies 76DA V.4.12 - Manual (Page 40)

Issue 9, May 2014 Model 76DA/77 User Guide
Page 40 Studio Technologies, Inc.
for Surround
management function requires the source
to have a sample rate of 44.1, 48, 88.2, or
96 kHz.) Selecting a source with a sample
rate of 44.1, 48, 88.2, or 96 kHz will re-
solve the issue and normal operation will
resume. Refer to the Technical Notes sec-
tion of this guide for additional details.
Downmix
Two downmix functions allow users to per-
form “real-world” audio format compatibility
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 pressing the de-
sired 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 and stereo digital and
analog monitor outputs. And, depending on
the selected configuration, they may also
impact the pre-fader surround digital moni-
tor output.
A specific downmix function can only be
enabled when it is applicable for the cur-
rently selected input source. This means
that the surround to stereo downmix func-
tion can only be enabled when surround
input A or B is selected.
The Model 77 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 surround to stereo downmix function
is enabled, this condition will be “remem-
bered” when switching to one of the stereo
input sources. Upon returning to surround
input A, the surround to stereo downmix
function will again become active.
Surround to Stereo
When the surround 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 con-
figuration, the LFE channel may also be
combined with the L and R signals. The
resulting stereo signal, sometimes known
as LtRt, is routed to the L and R post-fader
surround digital and analog monitor output
channels. Also, whenever the surround to
stereo downmix function is enabled the C,
LS, RS, and SUB digital and analog moni-
tor output channels are muted. By utilizing
this downmix function 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 SUB digital
and analog monitor output channels are
muted.
When a surround source has been select-
ed for monitoring, the surround 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
by folding down all channels associated
with the selected surround input.