Preamplifier Gain; Output Gain; Phantom Power - Audio Technica SmartMixer AT-MX341a Installation And Operation Manual

Mode 2...All Priority Pre-select switches Down
In this mode, only one mic at a time can be "on." The lockout bus shuts down all other mics
until the first speaker pauses. As soon as the controlling microphone goes silent, the lockout
bus goes inactive and any other mic can come on. This switching takes place without any
syllable-grabbing delay, or pops or clicks. (This mode is known as "First-come-first-served"
or "Filibuster.")
This mode is very useful when the gain setting of the overall sound system must be close to
the threshold of feedback, and additional microphones coming on could throw the system into
feedback. The SmartMixer will not allow multiple microphones to be on at the same time in this
mode. The switching is so fast and silent that the meeting can still be completely interactive.
Mode 3...One Priority Pre-select switch Up
The selected priority microphone can come on at any time and can override any other mic that
is on (popularly called "The Chairperson" mode).
(Note that there may be special circumstances where two or three mics could be set to priority,
so those speakers could talk whenever desired, but still override one or two non-priority mics.)
If multiple SmartMixers are used with AT8325/1.0 Link Cables, Priority Pre-select switches
on all channels in use will have the control effects described above.

Preamplifier Gain

The SmartMixer has a substantial gain range, allowing it to accept a wide variety of micro-
phones. However, if in some instances higher-output microphones are used for close talking,
it may be necessary to reduce the preamplifier gain. This can be done by changing switch
settings inside the unit. With the unit unplugged, remove the two screws on each side of the
unit and remove the top cover. Locate the internal switches designated on the circuit board
by "SW9," "SW10," "SW11" and "SW12" (Figs. 3 and 4, page 8). Changing the settings of these
internal switches will cause a gain reduction of 10 dB for channels 1, 2, 3 and 4 respectively.
The preamplifier gain may be reduced further, allowing the SmartMixer to accept line-level
sources. Changing the settings of the internal switches designated by "SW1," "SW2," "SW3"
and "SW4" 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 Gain

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 "SW15" (Figs. 3 and 4, page 8). Changing the setting of this switch will cause a
50 dB reduction in output.

Phantom Power

Each of the SmartMixer's inputs supplies +12V 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 "SW5," "SW6," "SW7" and "SW8" (Figs. 3 and 4,
page 8). 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.
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