User Guide

Model 780-01/790 User Guide Issue 4, December 2020
Studio Technologies, Inc. Page 43
for Surround
Error Code Err2
Err2 indicates that the Model 780-01 is
having problems with its internal logic
device. (A high-speed field-programmable
gate array (FPGA) serves as the digital
“heart” of the Model 780-01 and without
it no audio activity can occur.) The only
way to remedy this condition is to first try
removing and reconnecting mains power.
(And that’s a long-shot as to whether
it would accomplish anything.) If Err2 con-
tinues to be displayed the Model 780-01
must be returned to the factory for service.
Error Code Err3
If a digital audio source with a sample rate
of other than 44.1, 48, 88.2, or 96 kHz is
connected Err3 will display and the mute
all function will be automatically enabled.
In this scenario, selecting a different
source that has a sample rate of 44.1,
48, 88.2, or 96 kHz will return the system
to normal operation.
Error Code Err4
Err4 will display if communications with a
central controller has been established but
that specific central controller is not com-
patible with the Model 790. For example,
Err4 will display if a Model 790 has been
connected with a Model 760-Series central
controller.
Sample Rate Conversion
(SRC)
Circuitry associated with the stereo input
can provide sample rate conversion (SRC)
capability. A digital audio signal connected
to that input can have its sample rate and
timing re-synchronized to match the Model
780-01’s internal timing. While it would be
nice to proclaim that the engineers at Stu-
dio Technologies came up with a unique
and exotic circuit to perform this function
it’s really not the case. Several semicon-
ductor companies provide “single-chip”
SRC solutions and an excellent one from
AKM was selected for the Model 780-01.
The technical capabilities of the Model
780-01’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
780-01’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 780-01’s monitor output sample
rate is determined 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
780-01’s output sample rate. If a video
sync signal is connected, the Model
780-01’s sample rate is selected as part
of the configuration process.
So in practice what can the SRC function
accomplish? If the monitor output sample
rate is 48 kHz a signal connected to the
stereo input can have a sample rate from
8 to 216 kHz. Or, as another example, if
the Model 780-01’s monitor output sample
rate is 96 kHz a signal connected to the
stereo input can have its sample rate
range from 16 to 216 kHz.
As useful as allowing one sample rate
to be converted to another, it may be the
ability of the Model 780-01’s SRC function
to re-synchronize a signal that proves
most valuable. For example, in typical
post-production and broadcast applica-
tions all signals will have a sample rate
of 48 kHz. A Model 780-01 and all of its