Studio Technologies 76DBA V.3.00 - Manual (Page 46)

Issue 1, November 2010 Model 76DBA/77B User Guide
Page 46 Studio Technologies, Inc.
for Surround
Power Down
Great care was taken in the Model 76DBA’s
design to minimize the chance that clicks,
pops, or other objectionable audio signals
will be present on the digital and analog
monitor outputs. A power-down circuit sup-
plies the main microcontroller integrated
circuit with an indication that a power loss
is imminent. When this condition is detected
the digital monitor outputs will switch to
silence (audio “black”) in preparation for a
complete loss of signal. Electromechanical
relays associated with the analog monitor
outputs will change to their mute state to
minimize the change of signal transients
reaching the connected inputs.
Power-Up Messages and Error
Codes
Upon mains power being applied to the
Model 76DBA all connected Model 77B
units will go through a power-up sequence.
The sequence starts by each of the indi-
vidual LEDs lighting in a “walk-through”
sequence. Then the 4-digit display tests
all its LED segments. Finally, a set of mes-
sages provide details on the specific Model
77B and connected Model 76DBA software
versions:
1. Displays 77B
2. Displays Model 77B’s software version
3. Displays Model 77B’s unit address
(A1, A2, A3, or A4)
4. Displays 76db
5. Displays Model 76DBA’s main software
version
6. Displays FPgA
7. Displays Model 76DBA’s logic device
(FPGA) software version
After a successful system power-up
sequence normal operation will then com-
mence. Should a problem be encountered
during power up one of two error codes
may show on the Model 77B’s 4-digit
display. If Err1 displays it indicates that
communication is not taking place with
the Model 76DBA. The most likely cause
would be incorrect wiring of the data pair
linking the two units. Err2 indicates that the
Model 76DBA is having problems with its
internal logic device. (A high-speed field-
programmable gate array (FPGA) serves
as the digital “heart” of the Model 76DBA
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
the error code continues to be displayed
the Model 76DBA must be returned to the
factory for service. Note that for the vast
majority of StudioComm systems neither
of these error codes, especially Err2, will
ever appear.
Sample Rate Conversion
(SRC)
Circuitry associated with stereo input C
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
76DBA’s internal timing. While it would
be nice to proclaim that the engineers
at Studio Technologies came up with a
unique and exotic circuit to perform this
function it’s really not the case. Several
semiconductor companies provide “single-
chip” SRC solutions and an excellent one
from AKM was selected for the Model
76DBA. The technical capabilities of the
Model 76DBA’s SRC function is stated in