Audio Technica AT-MX351a SmartMixer, Installation And Operation Manual

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The preamplifier gain may be reduced further, allowing the SmartMixer to accept line-level
sources. Changing the settings of the internal switches designated by “S101,” “S201,” “S301”
and “S401” will cause an input reduction of 50 dB for channels 1, 2, 3 and 4 respectively.
Note that the appropriate internal switches can be used in combination for a total sensitivity
reduction of up to 60 dB for each channel.
Output Level
The SmartMixer’s output is factory set at line level. Should mic-level output be desired,
simply unplug the unit, remove the top cover and locate the switch on the circuit board
marked “S602” (Figs. 4 and 5, page 11). Changing the setting of this switch will cause a
50 dB reduction in output.
Phantom Power
Each of the SmartMixer’s inputs su48V DC phantom power. Should it be required
to disable the phantom power, simply unplug the unit, remove the top cover and locate the
switches designated on the circuit board by “S102,” “S202,” “S302” and “S402” (Figs. 4 and 5,
page 11). Changing the settings of these switches will disable phantom power on channels 1,
2, 3 and 4, respectively. Note that, although they do not require phantom power for operation,
most balanced-output dynamic microphones can be used without disabling the SmartMixer’s
phantom power.
Output Level LED Meter
The Output Level LED meter is factory set to indicate RMS output. Should peak output
indication be desired, simply unplug the unit, remove the top cover and change the setting of
the switch designated on the circuit board by “S603” (Figs. 4 and 5, page 11). “Zero” (0) level is
factory-calibrated at +4 dBm into 600 ohms.
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Summary of Internal Controls
Function Ch 1 Ch 2 Ch 3 Ch 4 Output
48V Phantom Power S102 S202 S302 S402
10 dB Input Atten. S103 S203 S303 S403
50 dB Mic/Line Atten. S101 S201 S301 S401 S602
Limiters (on/off) S106 S206 S306 S406
“Off” Atten. Range S105 S205 S305 S405
Preamp Output Gating S104 S204 S304 S404
Limiter Thresholds VOL103 VOL203 VOL303 VOL403
“Off” Atten. Adjustment VOL102 VOL202 VOL302 VOL402
NOMA -- -- -- -- S601
Meter RMS/Peak -- -- -- -- S603
Figure 3. Summary of internal controls