Studio Technologies 50 2005 - Manual (Page 33)

Model 50/51 User Guide Issue 7, August 2005
Studio Technologies, Inc. Page 33
What are the options if the operator(s) of
your Model 51 choose to use a “heavy”
hand on the switches? Two are read-
ily available: external communications
switches and an external source of
communications audio. A connector on
the back of the Model 51 allows the con-
nection of external talk to studio and talk
to phones switches. Using external switch-
es can eliminate the transfer of noise into
the Model 51’s microphone. The Mic
Module connector on the back of the
Model 50 allows an external source of
communications audio to be substituted
for the signal provided by the Model 51’s
microphone. Using a microphone and
simple preamplifier (or microphones and
an inexpensive mixer) you can optimize
the sound quality and location of the com-
munications mic(s). With the Model 51’s
microphone no longer in use, the switches
can be “beaten on” with no impact on
communications audio. For details on
how to implement external communication
switches or to use the Mic Module input
refer to other sections in the Advanced In-
stallation Topics section of this user guide.
Power Amplifier Input Sensitivity
Optimum StudioComm performance is
obtained when the input sensitivity of the
control room and studio power amplifiers
are adjusted to match the Model 50’s out-
put level. With normal, but loud, listening
levels you should find the level potentiom-
eters on the Model 51 to be set to about
11 or 12 o’clock. If you find that you don’t
have to turn up the Model 51’s controls
that high, reduce the input sensitivity of
the power amplifiers. Most power ampli-
fiers have controls on their inputs to allow
easy adjustment of the input sensitivity.
Control Room and Studio Output
Transient Protection
Unique to the Model 50 Central Control-
ler is a power up/power down transient
protection feature. This limits the chance
of damage to the control room and stu-
dio loudspeakers during the time when
AC mains voltage is connected, discon-
nected, or has significantly changed from
nominal. A combination of hardware and
software are used to monitor one of the
power supply “rails.” Until the power sup-
ply exceeds 81% of its nominal voltage,
electromechanical relays maintain a short
circuit condition on the control room A
and B outputs and the studio outputs.
After a one-second delay the relays are
released 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 upon power up the outputs
remained very quiet; during power down
a moderate “tick” was the worst that
was heard.