Studio Technologies 220 2013 - Manual (Page 16)

Issue 5, February 2013 Model 220 User Guide
Page 16 Studio Technologies, Inc.
of the Model 220’s enclosure. For conve-
nience, text and graphics on the security
plate provides a summary of the configu-
rable parameters and related information.
Refer to Appendix A for a representative
view. The security plate is held in place by
means of four rubber bumpers (“feet”) that
have built-in screws. Using your fingers,
remove the four bumpers so that the plate
can be removed. Refer to Figure 3 for a
detailed view of the configuration switch
assemblies.
preamplifier. The choices are 20, 30, 40,
50, and 60 dB. Only one switch should
be enabled at a time. There’s no problem
changing the gain setting while the unit
is operating. Audio clicks or pops might
occur during gain transitions, but this
shouldn’t be a major issue as long as
associated monitor loudspeakers are
temporarily attenuated or muted.
Selecting the correct amount of gain for an
application might take a little experimenta-
tion. The goal is to bring the mic’s signal
up to line level, nominally –2 dBu for the
Model 220’s main output. Operating at this
signal level will help to ensure the delivery
of “clean” audio to the connected device.
It’s also acceptable to connect a line-level
audio source to the microphone input. In
this case selecting 0 dB (no gain) would
be appropriate.
The output of the Model 220’s microphone
preamplifier is used by the main output
and, by way of the compressor circuit, the
talkback outputs. So creating a nice “hot”
signal will help maintain audio quality, spe-
cifically a high signal-to-noise ratio, when
driving the often-lengthy cable runs.
Figure 3. Bottom view of Model 220 showing
configuration switches, trim pots, and
compressor active LED
Microphone Preamplifier Gain
and Phantom Power
Five switches are used to set the gain of
the microphone preamplifier. One switch
is used to select the on/off status of the
phantom power supply.
Microphone Preamplifier Gain
Switches SW1-1 through SW1-5 are used
to select the gain of the microphone
Figure 4. Microphone preamplifier gain switch
settings