Orban OPTIMOD-FM 8600Si, Operating Manual

Page: 63 / 356

OPTIMOD-FM DIGITAL INSTALLATION
2-7
•
If an unbalanced output is required (to drive unbalanced inputs of other equip-
ment), it should be taken between pin 2 and pin 3 of the XLR-type connector.
Connect the
L
OW pin of the XLR-type connector (#3 or #2, depending on your
organization’s standards) to circuit ground; take the
H
IGH
output from the re-
maining pin. No special precautions are required even though one side of the
output is grounded.
•
Use two-conductor foil-shielded cable (Belden 8451, or equivalent).
•
At the 8600Si’s output (and at the output of other equipment in the system), do
not connect the cable’s shield to the CHASSIS GROUND terminal (pin 1) on the
XLR-type connector. Instead, connect the shield to the input destination. Con-
nect the red (or white) wire to the pin on the XLR-type connector (#2 or #3) that
is considered
H
IGH
by the standards of your organization. Connect the black wire
to the pin on the XLR-type connector (#3 or #2) that is considered
L
OW by the
standards of your organization.
AES3 Digital Input and Output
There are two digital outputs and two digital inputs, the second of which appears
on a BNC connector and also accepts AES3/AES3id or AES11/AES11id sync signals.
(See
AES3id Ratings Encoder Input on page 2-11.)
If you intend to use the BS.1770 Safety Limiter to drive a digital radio chain, we sug-
gest that you use Digital Output 1 to drive the digital radio transmitter. The BS.1770
safety limiter in the analog processing chain is calibrated with reference to 100%
modulation (see page 1-23) and is usable with the analog, digital, and composite
outputs.
The inputs and outputs are all equipped with sample rate converters and can oper-
ate at 32, 44.1, 48, 88.2, and 96 kHz.
Per the AES3 standard, each digital input or output line carries both the
left and right stereo channels. The connection is 110
Ω
balanced. The
AES3 standard specifies a maximum cable length of 100 meters. While
almost any balanced, shielded cable will work for relatively short runs (5
meters or less), longer runs require used of 110
Ω
balanced cable like
Belden 1800B, 1801B (plenum rated), multi-pair 180xF, 185xF, or 78xxA.
Single-pair category 5, 5e, and 6 Ethernet cable will also work well if you
do not require shielding. (In most cases, the tight balance of Category
5/5e/6 cable makes shielding unnecessary.)
The AES3id standard is best for very long cable runs (up to 1000 meters).
This specifies 75
Ω
unbalanced coaxial cable, terminated in BNC connec-
tors. A 110
Ω
/75
Ω
balun transformer is required to interface an AES3id
connection to your Optimod’s digital input or output (except for the
sync/audio input, which is terminated with 75
Ω
).
The digital input clip level is fixed at 0 dB relative to the maximum digital
word. The maximum digital input will make the 8600Si input meters dis-
play 0 dB. The reference level is adjustable using the
DI R
EF
control.