Studio Technologies 210 2008 - Manual (Page 16)

Issue 4, October 2008 Model 210 User Guide
Page 16 Studio Technologies, Inc.
they were included. It’s possible that
with a very “hot” microphone, such as a
phantom-powered condenser-type, 20 dB
of gain could be correct. It’s also possible
that a microphone with a very low-level
output, such as a ribbon-type, would need
60 dB of gain. But in general, the 30, 40,
and 50 dB gain settings will serve most
applications.
Note that if no gain switch is set to its ac-
tive (on) position the preamplifier will oper-
ate at unity (0 dB) gain. In this mode the
preamplifier remains stable, but is intend-
ed for use only during factory testing. A
valid exception would be where a line-level
signal is connected to the microphone in-
put. This could occur with a special Model
210 application. But with a microphone
connected as the input source one should
never use the 0 dB setting. The issue is
that with no gain added to the microphone
input signal, the relative noise floor on the
main and talkback outputs will be much
too high. These outputs are designed for
handling line-level signals, expecting to
receive the output of the mic preampli-
fier. In conclusion, the 0 dB gain setting
doesn’t highlight a problem, but simply
reflects the unit’s gain structure.
Phantom Power On/Off
The Model 210 can provide 48 volt
phantom power to the microphone input.
Switch SW1-8 controls whether or not
phantom power is active. By phantom
power’s very nature it could be left applied
to the microphone input at all times. But
generally people prefer to turn it off unless
required for a specific microphone.
Headphone Source Selection
Switch assembly SW2 is used to configure
the source or sources that are routed to
the stereo headphone output. The head-
phone sources are IFB channel 1, IFB
channel 2, auxiliary input 1, and auxiliary
input 2. The IFB channels are provided by
way of the IFB input connector located on
the Model 210’s back panel. The auxiliary
inputs are available only if the optional
line input cards have been installed or a
special Model 210 configuration has been
implemented.
Each of the available input sources can
be assigned to the headphone output’s
left channel, right channel, or both the
left and right channels. The Model 210’s
circuitry allows any combination of input
assignments to be made. For example,
consider the situation where a single-
channel IFB system, with both program
and interrupt audio on pin 3, is connected
to the Model 210. In this case it may be
desirable to assign this IFB signal to both
the left and right channels. This would en-
tail setting switches SW2-2 and SW2-6 to
their on positions. All other switches would
remain in their off positions.
A more complex application might have
a 2-channel IFB circuit connected to the
Model 210, with an optional line input card
installed and line-level audio from a golf
event “spotter” connected to that. In a
case such as this, it would be typical for
IFB channel 1 to be assigned to the head-
phone’s left channel, IFB channel 2 as-
signed to the right channel, and auxiliary
input 1 also assigned to the right channel.
Figure 5. Phantom power switch settings