Studio Technologies 76DA V.4.12 - Manual (Page 48)

Issue 9, May 2014 Model 76DA/77 User Guide
Page 48 Studio Technologies, Inc.
for Surround
to the factory for service. Note that for the
vast majority of StudioComm systems nei-
ther of these error codes, especially Err2,
will ever appear.
Error Code Err3
As previously discussed in this guide, the
bass management function only supports
input signals whose sample rate is 44.1,
48, 88.2, or 96 kHz. If during normal oper-
ation this condition is not met, it’s possible
that Err3 will display and the mute all func-
tion will be automatically enabled. This will
occur if the bass management function is
configured to be enabled for either or both
the surround and stereo post-fader monitor
outputs and an input with a non-compat-
ible sample rate has been selected. In this
scenario, selecting a different input with a
sample rate of 44.1, 48, 88.2, or 96 kHz
will return the system to normal operation.
Sample Rate Conversion
(SRC)
Circuitry associated with stereo input C
can provide sample rate conversion (SRC)
capability. A digital audio signal con-
nected to that input can have its sample
rate and timing re-synchronized to match
the Model 76DA’s internal timing. While
it would be nice to proclaim that the en-
gineers at Studio Technologies came up
with a unique and exotic circuit to perform
this function it’s really not the case. Sev-
eral semiconductor companies provide
“single-chip” SRC solutions and an excel-
lent one from AKM was selected for the
Model 76DA. The technical capabilities of
the Model 76DA’s SRC function is stated in
this way: the sample rate of an input signal
can range from 1/6 to six times the Model
76DA’s output sample rate, with the ad-
ditional restriction that it must be no less
than 8 kHz and no more than 216 kHz. The
Model 76DA’s output sample rate is de-
termined by the selected timing reference
(sync) signal and, if required, a configured
value. If a word clock, DARS (AES11), or
AES3 signal is the designated sync source
its rate will be the Model 76DA’s output
sample rate. If a video sync signal is con-
nected, the Model 76DA’s sample rate is
selected as part of the configuration pro-
cess.
So in practice what can the SRC function
accomplish? If the output sample rate is
48 kHz then a signal connected to stereo
input C can have a sample rate from 8 to
216 kHz. Or, as another example, if the
Model 76DA’s output sample rate is 96
kHz a signal connected to stereo input C
can have its sample rate range from 16
to 216 kHz.
As useful as allowing one disparate
sample rate to be converted to another,
it may be the ability of the Model 76DA’s
SRC function to re-synchronize a signal
that proves most valuable. For example,
in typical post-production and broadcast
applications all signals will have a sample
rate of 48 kHz. A Model 76DA and all of its
normally connected input signals will be
“locked” to the main timing reference signal
that supports the 48 kHz sampling rate.
But, as an example, a signal associated
with a portable device, while at a 48 kHz
sampling rate, may not be synchronized
(“genlocked”) to the “house” reference.
Connecting this signal to stereo input C will
cause the SRC function to “lock” it to the
Model 76DA’s rate, thus allowing it to be
monitored over a loudspeaker system. In
addition, the stereo input C direct monitor