Audio-Technica AT-MX351a 5-Channel Automatic Mixer

Audio-Technica AT-MX351a 5-Channel Automatic Mixer

Audio-Technica AT-MX351a 5-Channel Automatic Mixer

Audio-Technica AT-MX351a 5-Channel Automatic Mixer

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Product Highlights

  • 4 Automatic Mic/Line and 1 Aux Inputs
  • Individual Gain Controls per Input
  • Selectable 48V Phantom Power
  • Priority Pre-Select of Channels
  • Manages Overall Gain for Every Mic Added
  • Link Multiple Mixers Together
  • Output Level Meter with RMS and Peak
  • Headphone Output with Level Control
  • Off Attenuation of Inputs to -40 dB
  • Adapters for 1U Rack Mount
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Audio-Technica AT-MX351a overview

  • 1Description

The Audio-Technica AT-MX351a 5-Channel Automatic Mixer is designed for live applications such as teleconferencing, meetings, seminars, courtroom proceedings, worship services, radio, and TV broadcasting.

The mixer features 4 microphone input channels with +48 V phantom power and 1 auxiliary RCA input jack. A built-in microprocessor controls the signal processing and allows you to set priority-select switches for each microphone input channel. The priority-select switches determine which microphones will have priority and which microphone levels will be reduced and attenuated or "locked-out" of the output when the priority microphone(s) is on. This is useful for suppressing overall system feedback, balancing microphone levels, maintaining ambient sound, and for situations when only one microphone may be on at a time or one microphone must override the others.

Multiple mixers may be daisy-chained together with the included AT8325/1.0 link cable and the automatic attenuation settings will be applied to the whole system. The mixer can be mounted in a single 19" rack space using the included rack mount adapters.

Priority Pre-Select
The front panel of the mixer features "Priority Pre-Select" switches which determine which microphones will take priority and attenuate or lower the volume of other microphones in the system. When a channel's switch is down, that channel can be "locked out" or attenuated between 6 and 40 dB by the other microphones in the system. When the switch is up, the microphone cannot be attenuated.

In the first "Free-for-all" or "City-Council" mode wherein all the switches are "UP," the other microphones will remain on when the priority microphone(s) are active. This is useful for applications when any speaker is allowed to speak at any time.

In the second "First-come-first-serve or "filibuster" mode wherein the microphone switches are "Down," the non-priority microphones will be attenuated by an adjustable value of 6 to 40 dB when the priority microphone is active. After the priority microphone stops, any microphone may come on but only one microphone may be active at a time. This mode is useful for applications when it is beneficial to have one person talking at a time.

In the third "Chairperson Mode," wherein one priority pre-select switch is up, the priority microphone(s) can come on at any time and attenuate the other microphones. This mode is useful for applications when one speaker must be able to interrupt and speak over the other speakers
NOMA (Number of Open Microphones)
When enabled, the NOMA (Number of Open Microphones Attenuated) switch maintains the overall system gain by reducing the amplifier gain of each additional microphone added to the system. This is useful for suppressing feedback and maintaining a consistent overall output signal
For applications that require more than four microphones, multiple mixers may be daisy-chained together by the included AT8325/1.0 Link cable. When connected, the link out of the first mixer is connected to the link in of the second mixer, so that the audio output of the second mixer will be both that of the first and the second. The audio output for the application is taken from the last mixer in the chain. When multiple mixers are daisy-chained together the priority-select settings of each mixer are sent through the chain such that any microphone in the chain can determine the attenuation or "lock-out" of the other microphones in the chain
Auxiliary Input
The mixer includes an Auxiliary RCA input jack that accepts -10 dBV input from an external audio device such as a CD player. The auxiliary input does not have any signal processing
Phantom Power
Each microphone input can supply +48 VDC phantom power. Phantom power may be disabled by removing the amplifier's top cover and throwing the switches "S102," "S202," "S302," and "S402" for input channels 1, 2, 3, and 4 respectively. Though phantom power is not required for their operation, most balanced dynamic microphones will work without having to disable phantom power
Output Level
The mixer can output either a line level signal or switched to a microphone level signal by unplugging the power, removing the top cover, and throwing the switch on the circuit board labeled "S602." Switching to a microphone level signal reduces the output by 50 dB
Output Level LED Meter
The output level LED meter can display either RMS or be switched to peak output by unplugging the power, removing the top cover, and throwing the switch on the circuit board labeled "S603"
"Off" Attenuation
Internal trim pots allow you to adjust the level of microphone attenuation between 6 dB and 20 dB
Preamp Outputs
Separate from the main mixer output, each channel has its own unbalanced preamp output for connecting to a recorder. Each of these outputs may be gated by unplugging the power, removing the top cover, and throwing the switches labeled "S104," "S204," "S304," and "S404" for pre-amps 1, 2, 3, and 4 respectively
Input Limiters
Each microphone input channel has an adjustable limiter between -10 dB RMS and +10 dB RMS that may be adjusted by unplugging the power, removing the top cover, and turning the trimpots labeled "VOL103", "VOL203", "VOL303", and "VOL403" for inputs 1, 2, 3, and 4. To turn off the limiters completely, unplug the power, remove the top cover, and flip the switches on the circuit board labeled "S106," "S206," "S306," "S406"
By connecting a closure pin and ground reference to the appropriate external control connector on the back panel of the mixer, it is possible to force a channel to be either on or off
Control Voltage Out
When a microphone input turns on, it is possible to use the channel's +4 VDC control voltage out to light indicator lamps, select video cameras, and switch speaker zones
Rack Mounting
Included with the mixer are two rack ears and self-tapping screws to mount the mixer in a 1 unit 19" rack space
Security Caps
For installations wherein you don't want input settings changed after they have been calibrated, the mixer comes with seven security caps that attach to and lock the front panel control knobs
In the Box
Audio-Technica AT-MX351a 5-Channel Automatic Mixer
  • AC Power Cable
  • 3.3' (1 M) AT8325/1.0 Link Cable
  • 2 x Rackmount Adapters
  • 7 x Security Caps
  • Limited 2-Year Warranty
  • Table of Contents
    • 1Description

    Audio-Technica AT-MX351a specs

    Inputs 4 x balanced XLR microphone inputs
    1 x unbalanced RCA auxiliary in
    1 x AT8325/1.0 link input port
    1 x 15 pin D-Sub external control connector for external control of each channel
    Outputs 1 x balanced XLR line/mic output
    4 x unbalanced RCA pre-amplifier outputs
    1 x AT8325/1.0 link output port
    1 x 15 pin D-Sub external control connector for transistor-transistor logic output
    Input Impedance Mic: 8 kΩ
    Line: 50 kΩ
    Aux: 50 kΩ
    Link In: 20 kΩ
    Output Impedance Balanced Line: 200 Ω
    Mic: 300 Ω
    Unbalanced: 400 Ω
    Link Out: 100 Ω
    Preamp Out: 750 Ω
    Maximum Input Level Mic: -24 dBV
    Line: +27 dBV
    Aux: +17 dBV
    Maximum Output Level +22 dBm
    Nominal Output Level (0 VU) Balanced Line: +4 dBm (600 ohms), +4.4 dBV (open circuit)
    Mic: -46 dBm (600 ohms), -44 dBV (open circuit) Unbalanced: -10 dBV (open circuit) Preamp Out: -10 dBV (open circuit)
    Monitor Output 700 mW at 20 Ω load
    Maximum Gain 73 dB
    Frequency Response 40 to 22,000 Hz
    Equivalent Input Noise -128 dBV (150 Ω) at maximum gain
    Input Attenuation 10 dB
    Input Pad Switch 50 dB
    Attenuation Maximum NOMA: approximately 20 dB (up to 100 mics on simultaneously)
    Phantom Power +48 VDC
    Control Voltage Out +4 VDC
    Power Supply 100 to 240 VAC at 50 to 60 Hz
    Power Consumption 30 W
    Operating Temperature 32 to 104 °F (0 to 40°C)
    Dimensions (WxDxH) Including knobs, feet, and connectors: 16.93 x 9.38 x 1.75" (430 x 238 x 44 mm)
    Weight 7.38 lb (3.35 kg)
    Packaging Info
    Package Weight 10.9 lb
    Box Dimensions (LxWxH) 21.6 x 15.5 x 3.7"

    Audio-Technica AT-MX351a reviews

    AT-MX351a 5-Channel Automatic Mixer is rated 5.0 out of 5 by 2.
    Rated 5 out of 5 by from Quick, responsive, and with many uses This unit is headlined as a automatic mic mixer, and it does that extremely well and very fast. It is virtually undetectable in its switching between mic in conversations. However, it is a very flexible device and can be configured in many ways. For example, I use it as an audio gate. I have it listening on one of its 4 inputs, other than Channel 1, while I pass program audio through on Channel 1 and out through its aux out port for Channel 1, instead of Master out. When it hears sound on the listening port, it effectively cuts out the program audio, per my application. The device is well-built and flexible. My only complaint is that for many of the configuration switches, you have to take off the top cover.
    Date published: 2015-06-14
    Rated 5 out of 5 by from Works perfectly! We needed automatic microphone gating that was distributed from a broadcast envirmoment onto a streaming media application & it worked like a charm straight out of the box!
    Date published: 2012-08-14
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