Studio Technologies 220 2004 - Manual (Page 15)

Issue 2, August 2004 Model 220 User Guide
Page 16 Studio Technologies, Inc.
and related information. Refer to Appendix
A for a representative view of the label. 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. 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 as-
sociated monitor loudspeakers are tempo-
rarily attenuated or muted.
Figure 4. Microphone preamplifier gain switch
settings
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 pre-
amplifier. The choices are 20, 30, 40, 50,
and 60 dB. Only one switch should
be enabled at a time. There’s no problem
Figure 3. Bottom view of Model 220 showing
configuration switches, trim pots, and
compressor active LED
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.
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,
specifically the signal-to-noise ratio, when
driving the often-lengthy cable runs.
Unfortunately, there’s no “perfect” gain
setting that this guide can recommend.
The two issues that impact the setting
are output sensitivity of the connected
microphone and the acoustical output