AT-MX351 SmartMixer Automatic Mixer Installation and Operation
Contents Introduction ........................................................................................................................5 What is a SmartMixer ? . ..........................................................................................................5 Features . ....................................................................................................................................5 Front Panel . ............................................................................
Safety Cautions Prior to use of this product, review all safety markings and instructions. CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN AVIS RISQUE DE CHOC ÉLECTRIQUE NE PAS OUVRIR To prevent electric shock, do not remove the cover. There are no user-serviceable parts inside. Internal adjustments are for qualified professionals only. Refer all servicing to qualified service personnel. Pour prévenir un choc électrique, ne pas ouvrir le couvercle. Il n’y aucune pièces de rechanges à l’intérieur.
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 10 for details. What is a SmartMixer? The AT-MX351 SmartMixer® is a microprocessor controlled, automatic switching, five-channel mixer.
AT-MX351 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. Aux In control. Adjusts input for source output level and/or operating conditions. 6. Output Level LED meter. Indicates RMS output level of the mixer.
AT-MX351 Rear Panel 1. External Control connector. For TTL output, plus closure-control input for external control of each channel. 2. Link In/Link Out. Provides for daisy-chaining of multiple mixers when more than four microphones are used. 3. Line/Mic balanced output. Level can be changed via internal switch (see page 10). XLRM-type connector. 4. Unbalanced line-level (–10 dBV) output. RCA jack. 5. Aux In. Unbalanced, line-level (–10 dBV), auxiliary input. 6. Preamp Outputs.
Installation and Setup AT-MX351 SmartMixer setup tips: 1. Turn the Master level control to the minimum position. Proceed with steps 2-9. 2. Set all Priority DIP switches and Manual mode switch to “down” position. 3. Turn all four microphone Gain controls fully counterclockwise. 4. Connect the power cord to the mixer and plug into AC outlet. Be certain the voltage switch on bottom of unit is set for the voltage of the outlet you are using. 5. Turn Power switch “on.
Mode 2…Priority Pre-select switches (1-4) 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.
The preamplifier gain may be reduced further, allowing the SmartMixer to accept line-level sources. Changing the settings of the internal switches designated by “SW3,” “SW9,” “SW15” and “SW21” 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.
Rear Panel SW26 SW25 SW27 Front Panel Figure 4. Internal view of mixer. Mic Mic SW3 Mic SW9 Mic SW15 Line SW21 Line Line Line Line Phantom 40 dB SW1 Phantom 40 dB SW7 SW2 Phantom 40 dB SW13 SW8 Phantom 40 dB SW19 SW14 SW26 Outpu t SW20 Mic Off 30 dB Off 30 dB Off Off VR6 –6 dB –10 dB SW5 Min. Off SW18 Gating –20 dB 30 dB Off SW12 Gating Min. Off Off SW6 VR3 30 dB Gating VR9 –20 dB –6 dB SW11 SW24 Gating VR12 –20 dB Min. –6 dB SW17 Min.
Adjusting ”Off” Attenuation In instances when the number of microphones in use is high, it may be necessary to increase the amount of “off ” attenuation per microphone to keep the total ambient noise level low. There are “off ” attenuation adjustments inside the unit. To adjust the “off ” attenuation of channel 1, unplug the unit, remove the top cover and locate the trimpot designated on the circuit board by “VR3” (Figs. 4 and 5, page 11).
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). See chart on page 12 for pin connection. 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.
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 their back panels (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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . Line . . . . . . . . . . . . . . . . . . . . . . . . . . . Aux . . . . . . . . . . . . . . . . . . . . . . . . . . . . Link In . . . . . . . . . . . . . . . . . . . . . . . . 8,000 ohms 50,000 ohms 50,000 ohms 20,000 ohms Output Impedance Balanced Line . . . . . . . . . . . . . . . . . . . . . . . . . Mic . . . . . . . . . . . . . . . . . . . . . . . . . . Unbalanced . . . . . . . . . . . . . . . . .
One-Year Limited Warranty Audio-Technica brand products purchased in the U.S.A. are warranted for one year from date of purchase by Audio-Technica U.S., Inc. (A.T.U.S.) to be free of defects in materials and workmanship. In event of such defect, product will be repaired promptly without charge or, at our option, replaced with a new product of equal or superior value if delivered to A.T.U.S. or an authorized service center prepaid, together with the sales slip or other proof of purchase date.
