Studio Technologies 78 2004 - Manual (Page 11)

Model 78/79 User Guide Issue 5, January 2004
Studio Technologies, Inc. Page 11
for Surround
of an audio patch bay. This will allow the
channels associated with that input source
to be easily rerouted. While signals gener-
ated within a facility will normally follow a
specific format, such as L, R, C, LFE, SL,
SR, BL, and BR, it is possible that media
provided by an outside facility will follow a
different one.
Monitor Output
The connector labeled output provides
access to the 8-channel monitor output.
Please refer to Figure 5 for details on the
exact “pin out” of the D-sub connector.
The monitor output channels are intended
for connection to audio amplifiers associ-
ated with monitor loudspeakers, or to the
inputs of loudspeakers that contain inte-
grated amplifiers. The monitor outputs are
electronically balanced and capable of
driving balanced or unbalanced loads of
600 ohms or greater. While balanced op-
eration is preferred, unbalanced operation
does not pose a problem. To connect to an
unbalanced load connect the + terminal
as signal high, and both the – and shield
as the signal low/shield. For optimal unbal-
anced operation, it is important to connect
both – and shield together directly on the
D-sub plug, not at the other end of the
harness.
Note that while the Model 78’s electroni-
cally balanced output circuits are capable
of driving loads of 600 ohms or greater,
the output level will drop slightly as the
load impedance approaches 600 ohms.
A 0.5 dB difference in output level can be
expected as the load impedance changes
from 10 k ohms to 600 ohms.
Remote Control Inputs
Support is provided for three remote con-
trol input functions: mute all, dim, and input
select. The inputs use logic gates, “pulled
up” to +5 V by way of resistors, which are
active when brought to the logic low state.
Inputs of this type are commonly referred
to as GPI inputs. While the input circuitry
is protected from over-current and static
(ESD) discharge, care should be taken to
prevent nasty signals from reaching them.
The inputs are active only when held in
the low state; they can’t be configured to
change state (“latch”) in response to a
logic pulse.
The connector labeled Remote Control
Inputs on the back panel of the Model 78
is used to interface with the remote control
inputs. Refer to Figure 6 for exact connec-
tion details. Note that pin 1 (Shield) and
pin 9 (Remote Control Common) are elec-
trically identical. In addition to connecting
to system common, they connect to the
Model 78’s chassis and mains earth con-
nection. For convenience, the shield of the
interconnecting cable should be connected
to pin 1 (Shield), while the return signals of
the remote control sources should connect
to pin 9 (Remote Control Common).
Note that although the remote control con-
nections are physically made to the D-sub
on the Model 78’s back panel, the remote
control input circuitry is actually located in
the Model 79 Control Console. Conduc-
tors in the cable linking the Model 78 to the
Model 79 route the remote control signals
to the actual input circuitry.