AT-MX341b SmartMixer ® Automatic Microphone Mixer AUTOMATIC MICROPHONE MIXER Gain 1 Gain 2 Gain 3 AT-MX341b Master Threshold Output Level Gain 4 -20 -10 -6 -3 0 +3 +6 Priority Pre-select Manual Power Selected Channel Installation and Operation 1 2 3 4 Master Level Lockout
Contents Introduction .....................................................................................................................3 ‚ What is a SmartMixer ? .........................................................................................................3 Features ..................................................................................................................................3 Front Panel ....................................................................................
Introduction Please Note! This manual assumes use of microphone-level inputs and line-level output, the most typical SmartMixer application. However, all inputs and the output may be individually switched internally to achieve any combination of mic- and line-level input/output. See page 8 for details. About internal adjustment Operating personnel must not remove equipment covers. Only qualified, experienced, authorized service personnel may remove equipment covers for any internal adjustments.
AT-MX341b Front Panel 1. Power switch. 2. Power “on” indicator. 3. Input Gain controls. Adjust inputs for microphone sensitivities and/or operating conditions. 4. Selected Channel LED indicators. Indicate which channels are “on” or “active.” 5. Output Level LED meter. Indicates RMS output level of the mixer. “Zero” (0) level is factory calibrated for an output of +4 dBm into 600 ohms (Master Level control fully clockwise). Can be set for peak output level indication via internal switch (see page 8). 6.
AT-MX341a Rear Panel AUTOMATIC MICROPHONE MIXER AT-MX341b Master Output Level 1. Power input. Gain Requires 12 volts AC or 15-18Gain volts DC, either polarity; 300 mA. Threshold 1 Gain 2 Gain 3 4 0 -3 +3 +6 -20 -10 -6 2. Link In /Out. Provides for daisy-chaining of multiple mixers when more than four microphones are used. Priority Pre-select Manual 3. Control Voltage Out.
Installation and Setup AT-MX341b SmartMixer setup tips: 1. Turn Master Threshold control to minimum threshold, immediately clockwise of the “Manual” setting. 2. Set all Priority DIP switches to “down” position. 3. Turn all four microphone Gain controls fully counter-clockwise. 4. Connect the AC adapter to the mixer and plug in to outlet. 5. Turn Power switch “on.” The mixer will perform a self-test and turn each microphone “on” and “off ” consecutively. 6.
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.
Rear Panel 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 “S602” (Figs. 3 and 4). “Zero” (0) level is factory-calibrated at +4 dBm into 600 ohms. Don't Touch ! Figure 3. Internal view of mixer.
Control Voltage Out When a microphone channel turns “on,” as indicated by a Selected Channel LED on the front panel, the channel’s associated Control Voltage Out goes “high” (+4 VDC). This signal can be used to light indicator lamps, switch speaker zones on and off, select video cameras, etc. The control voltage should not be connected directly to an inductive load such as a relay coil, as damage to the mixer may result. Several interface circuit possibilities are shown in Figure 5. Figure 5.
Daisy-chaining Mixers When more than four microphones are needed, it is possible to daisy-chain multiple SmartMixers together through the Link In/Out connectors on the backs of the units (Fig. 2). Connect Mixer #1 Link Out jack to Mixer #2 Link In jack, etc. Mixer #1 output contains only audio from the first four microphones; Mixer #2 output then contains audio from all the microphones plugged into Mixer #1 and the microphones plugged into Mixer #2.
Specifications † Input Impedance Mic . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,000 ohms Line . . . . . . . . . . . . . . . . . . . . . . . . . . . 30,000 ohms Output Impedance Line . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 ohms Mic . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 ohms Maximum Input Level Mic . . . . . . . . . . . . . . . . . . . . . . . . . . . –20 dBV Line . . . . . . . . . . . . . . . . . . . . . . . . . . . +30 dBV Maximum Output Level* Line . . .
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