Studio Technologies 68 V.1 - Manual (Page 33)

Model 68/69 User Guide Issue 2, June 1999
Studio Technologies, Inc. Page 33
for Surround
operating parameters as stored in its
memory. You may notice a brief interval
of silence while the Model 68 responds to
the reset defaults and operating parameter
messages.
Power Amplifier Input Sensitivity
Optimum StudioComm performance is
obtained when the input sensitivity of the
associated audio power amplifiers or
amplified speakers is adjusted to match
the Model 68’s monitor output level. With
normal, but loud, listening levels you
should find the level potentiometer on the
Model 69 to be set at approximately the
“2-o’clock” position. If you find that you
don’t have to turn up the Model 69’s con-
trol that high, reduce the input sensitivity of
the power amplifiers until you get to the
2-o’clock position. Most power amplifiers
and amplified speakers have controls on
their inputs to allow easy adjustment of
input sensitivity.
Monitor Output Transient Protection
The Model 68 Central Controller contains
a power up/power down transient protec-
tion feature. This limits the chance of
damage to the monitor loudspeakers
during the time when AC mains voltage
is connected, disconnected, or has
changed significantly from nominal. A
combination of hardware and software is
used to monitor one of the power supply
“rails.” Until the power supply exceeds
81% of its nominal voltage, electrome-
chanical relays maintain a short circuit
condition on the monitor outputs. After a
short delay the relays are allowed to
function normally. Whenever the power
supply drops below 79% of its nominal
voltage, the relays immediately go to their
mute state. During testing it was found that
Pin Signal Direction
1 Power Supply Common 68 to/from 69
2 +15Vdc 68 to 69
3 Data (MIDI System-Exclusive) 69 to 68
4 Data Common 69 to/from 68
5 Remote Mute All 68 to 69 (Note 2)
6 Remote Dim 68 to 69 (Note 2)
7 Remote L/R Bypass 68 to 69 (Note 2)
8 Remote Input Select 68 to 69 (Note 2)
9 Remote Control Common 68 to/from 69
Notes: 1) Connector types on Model 68 and Model 69 are 9-pin
D-subminiature female. Connectors use 4-40 threaded
inserts for locking with mating plug.
2) Remote control sources connect to D-sub on Model
68, then passively route to 68/69 interface D-sub.
Figure 8. Connections between Model 68 and
Model 69
upon power up the monitor outputs re-
mained very quiet; during power down a
moderate “tick” was the worst that was
heard.
Model 68 to Model 69
Connections
Figure 8 gives a detailed view of the sig-
nals that connect between the Model 68
Central Controller and the Model 69
Control Console. The Model 68 provides
+15Vdc power for the Model 69. The
Model 69 generates MIDI system-exclu-
sive messages and sends them to the
Model 68. From the outside world, the
four remote control input sources connect
to the Model 68. They then route, via the
interface cable, from the Model 68 to
the actual input circuitry, located in the
Model 69.