Cardioid Condenser Boundary Microphone

MSRP* US$269.00
Two-Year Limited End-User Warranty

*Manufacturer's Suggested Retail Price. Actual selling price may vary; please check with an authorized Audio-Technica dealer.

  • Overview
  • Features
  • Specifications
  • Downloads
  • Reviews
  • Q & A

  • Overview

    Offering outstanding Audio-Technica sound for surface-mount applications, the U851A features a PivotPoint® rotating output connector, UniSteep® filter and UniGuard® RFI-shielding technology. This battery- or phantom-powered condenser microphone accepts interchangeable condenser elements—available for boundary microphones in cardioid, hypercardioid and omnidirectional polar patterns. Its heavy die-cast case and silicon foam bottom pads minimize coupling of surface vibration to the microphone. With superior off-axis rejection and maximum gain-before-feedback, this professional microphone sets audio-quality standards in challenging acoustic environments.
  • Features

    • Designed for surface-mount applications such as high-quality sound reinforcement, professional recording, television, conferencing and other demanding sound pickup situations

    • PivotPoint® rotating output connector allows cable to exit from either the rear or the bottom of the microphone

    • Superior off-axis rejection for maximum gain before feedback

    • UniGuard® RFI-shielding technology offers outstanding rejection of radio frequency interference (RFI)

    • UniSteep® filter provides a steep low-frequency attenuation to improve sound pickup without affecting voice quality

    • Small-diameter UniPoint capsule near boundary eliminates phase distortion and delivers clear, high-output performance

    • Heavy die-cast case and non-slip silicone foam bottom pads minimize coupling of surface vibration to the microphone

    • Low-profile design with low-reflectance black finish for minimum visibility

    • Operates on battery or phantom power

  • Specifications

    ELEMENTFixed-charge back plate, permanently polarized condenser
    POLAR PATTERNHalf-cardioid
    (cardioid in hemisphere above mounting surface)
    LOW FREQUENCY ROLL-OFF80 Hz, 18 dB/octave
    OPEN CIRCUIT SENSITIVITYPhantom: –40 dB (10.0 mV) re 1V at 1 Pa
    Battery: –41 dB (8.9 mV) re 1V at 1 Pa
    IMPEDANCEPhantom: 200 ohms
    Battery: 270 ohms
    MAXIMUM INPUT SOUND LEVELPhantom: 133 dB SPL, 1 kHz at 1% T.H.D.
    Battery: 123 dB SPL, 1 kHz at 1% T.H.D.
    DYNAMIC RANGE (typical)Phantom: 111 dB,1 kHz at Max SPL
    Battery: 101 dB, 1 kHz at Max SPL
    SIGNAL-TO-NOISE RATIO72 dB, 1 kHz at 1 Pa
    BATTERY CURRENT / LIFE0.4 mA / 1200 hours typical (alkaline)
    SWITCHOff, on-flat, on-roll-off
    WEIGHT (MICROPHONE)8.6 oz (244 g)
    WEIGHT (POWER MODULE)4.9 oz (139 g)
    DIMENSIONS (MICROPHONE)4.25" (108.0 mm) long,
    3.31" (84.0 mm) maximum width,
    0.91" (23.0 mm) height
    DIMENSIONS (POWER MODULE)3.31" (84.0 mm) H x
    2.48" (63.0 mm) W x
    0.87" (22.0 mm) D
    CABLE25.0' (7.6 m) long (permanently attached to microphone), 0.13" (3.2 mm) diameter, 2-conductor, shielded cable with TA3F-type connector
    UE-O omnidirectional (360°)
    ACCESSORIES FURNISHEDAT8531 power module; battery; soft protective pouch
    Click on the chart to view the larger image

  • Downloads

    UniPoint Review - Sound & Video Contractor (pdf 128.21 KB)
    UniPoint Review - Pro Audio Review (pdf 238.70 KB)
    U851A Specification Sheet (pdf 330.95 KB)
    U851A Submittal Sheet (pdf 512.47 KB)
    Optional Windscreens / Mounts
  • Reviews

  • Q & A

    Do you have questions about this product?

    Get answers from real customers and in-house experts with AnswerBox.

    4 Questions | 4 Answers
    Displaying questions 1-4
    • Q:

      What is this mic best useage on a stage performance? Can it pick up stinged sections in an orchestra?
      Asked on 3/20/2017 by matrex2 from Toronto

      1 answer

      • Staff Reviewer


        The U851A microphone is a good choice for orchestra pickup. Other popular choices are the U853R microphones which may be hung from above or used on a microphone stand and the AE5100.

        Answered on 3/22/2017 by ATUS_Specialist3
    • Q:

      can this mic be used as stage mic for dramatic performances?
      Asked on 12/17/2015 by Ray from N.Y.

      1 answer

      • Staff Reviewer


        Thank you for your inquiry. Yes, we have customers that use the mic for this application.

        Answered on 12/19/2015 by AudioSolutionsManager from Audio-Technica U.S., Inc.
    • Q:

      Is it possible to replace the cable? It appears to be built in to the mic. Our custodian decided to vacuum the cord . . .
      Asked on 10/27/2015 by Brad from United States

      1 answer

      • Staff Reviewer


        Please contact our Service Department at (330) 686-2600 ext 5003 or at Service@atus.com for assistance with this.

        Answered on 10/29/2015 by ATUS_Specialist3
    • Q:

      Can I put a regular XLR connector on it

      U851A Cardioid Condenser Boundary Microphone
      Asked on 4/30/2012 by Michel from Montreal, QC, Canada

      1 answer

      • A:

        Thank you for your inquiry. No, you must use the power module. The power module attached to some condenser microphones provides several important functions. First, it converts the 11 – 52 VDC phantom power into a smaller DC bias voltage used to power the FET impedance matching circuit inside the microphone. Also, it provides low frequency roll off, supplies battery power if phantom power is not available, converts the signal to the proper impedance and balances the output. The power module is a necessary component.

        Please note this mic is available as a phontom power only version that has just an XLR connector (U851R).

        Answered on 5/9/2012 by AudioSolutionsManager from Stow, OH
    Displaying questions 1-4

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