Studio Technologies 780-03 V.4.15 - Manual (Page 10)

Issue 1, April 2015 Model 780-03/790 User Guide
Page 10 Studio Technologies, Inc.
for Surround
The audio inputs support digital audio
signals with sample rates of up to 44.1,
48, 88.2, and 96 kHz and a depth (word
length) of up to 24 bits. It’s recommended
that the connected signal sources maintain
a common sample rate and timing refer-
ence. Having all signals “locked” together
helps to ensure proper handling by the
Model 780-03’s all-digital signal path.
There is, however, an exception worth
noting. Circuitry associated with the stereo
input has sample rate conversion (SRC)
capability, allowing virtually any stereo digi-
tal audio signal to be connected. A signal
connected to the stereo input can have an
independent sample rate and timing refer-
ence while still being monitored correctly.
Refer to the Technical Notes section of this
user guide for a detailed review of the SRC
capability.
The Model 780-03’s audio inputs are in-
tended for connection with balanced digital
audio sources that are compatible with the
AES3 standard. This type of signal has a
nominal impedance of 110 ohms and a
nominal signal level of 5 Vpp.
One 25-pin female D-subminiature con-
nector (DB-25F) is used to interface with
the 16 channels associated with surround
input A and surround input B. Each of
the eight connections supports two audio
channels. Often a wiring assembly pre-
pared for these digital audio inputs would
be identical to that of a TASCAM®-type
(AES59-compliant) input assembly. A typi-
cal assembly of this type will often have
eight 3-pin female XLR connectors on one
end and a 25-pin male D-subminiature
connector (DB-25M) on the other. Refer to
Figure 4 or Appendix A for details on con-
necting with the 25-pin female D-subminia-
ture connector.
Note that unlike a TASCAM-type assem-
bly, the two threaded fasteners associated
with the Model 780-03’s D-subminiature
connector use 4-40 threads. This complies
with the original design standard for D-sub
connectors.
On the Model 780-03 the stereo input uses
a 3-pin female XLR connector for interfac-
ing with a digital audio source. The mating
cable should have a 3-pin male XLR con-
nector wired such that the + signal goes
to pin 2, the – signal to pin 3, and shield to
pin 1.
Unbalanced AES3 digital audio signals
can also be used with the Model 780-03’s
inputs if external coupling transformers
(“baluns”) are utilized. These impedance-
matching (75 ohms to 110 ohms) and level
step-up transformer assemblies typically
provide a BNC connector on their input
and a 3-pin male XLR connector on their
output.
Signal Signal
Connections Channel High (+) Low (–) Shield
Surround Input A L/R 1 24 12 25
Surround Input A C/LFE 2 10 23 11
Surround Input A SL/SR 3 21 9 22
Surround Input A BL/BR 4 7 20 8
Surround Input B L/R 5 18 6 19
Surround Input B C/LFE 6 4 17 5
Surround Input B SL/SR 7 15 3 16
Surround Input B BL/BR 8 1 14 2
Notes: 1) All signals transformer-coupled digital audio;
balanced AES3 (110 ohms, 5 Vpp) compatible.
2) Connector type on Model 780-03 is 25-pin female
D-subminiature (DB-25F). Installer must provide male
(DB-25M). Connector uses 4-40 threaded inserts for
locking with mating plug.
3) Wiring scheme follows AES59-2012 convention.
Standard TASCAM-type wiring harnesses are directly
compatible, with the possible exception of 4-40 screw
threads being required.
Figure 4. Connections for Surround A and
Surround B Digital Inputs