AT831b MINIATURE CARDIOID CONDENSER MICROPHONE Description Operation and Maintenance Architects and Engineers Specifications The AT831b is a miniature condenser microphone with a cardioid polar pattern. It has been designed for hands-free applications in sound reinforcement systems, and for use by professional musicians, especially for pickup of acoustic guitar. The AT831b provides improved gain before feedback that normally cannot be achieved with miniature omnidirectional microphones. Close-up voice and instrument pickup are crisp and clean, yet full sounding, while suppression of background noise is significantly improved over that of standmounted full-size cardioid microphones. To install the battery, remove the cap from the top of the power module. Insert the battery, being certain to observe battery polarity as marked (+ end toward the cap release button). For longest battery life, the switch should remain off except when the microphone is in use. While standard carbonzinc AA batteries will operate the microphone satisfactorily, alkaline or mercury cells are preferred for longer service life. Only “leakproof” batteries should be used. The battery does not have to be in place to use in phantom power mode. Phantom power requires 9V to 52V DC. The microphone shall be a fixed-charge condenser with a cardioid polar pattern and a frequency response of 40 Hz to 20,000 Hz. It shall operate from an external 9V to 52V DC phantom power source or, alternatively, from a 1.5V AA / UM3 battery. Nominal opencircuit output voltage shall be 6.3 mV (phantom) or 5.6 mV (battery) at 1 kHz, 1 Pascal. Output with the included power module shall be low impedance balanced (200 ohms-phantom, 270 ohms-battery). Audio -Technica design engineers have utilized the newest low-mass technology in the quest for superior performance. The permanent charge is now on the fixed back plate, rather than the moving element. With A-T fixed charge “back plate“ construction, a gold-vaporized diaphragm just 2 microns thick (about 0.000079") can be used. This reduces moving mass, thus improving frequency response and transient response while reducing distortion. The microphone may be worn on the person or attached to a musical instrument. If used with an instrument, it may be attached by means of the clothing clip or the special instrument adapter provided. The power module may be worn on the belt, utilizing the belt clip, or located in any convenient place. An open-pore foam windscreen simply slips over the head of the microphone, effectively reducing wind noise or “popping” when used extra close. The AT831b can be powered from an external 9V to 52V DC phantom supply or from an AA/UM3 1.5V battery (supplied). Current demands are so low that an alkaline battery will provide about 1200 hours of continuous use. Output is low impedance balanced. The XLRM-type output connector mates with XLRF-type cable connectors. The balanced signal appears across Pins 2 and 3, while the ground (shield) connection is Pin 1. Output is phased so that positive acoustic pressure produces positive voltage at Pin 2 in accordance with industry convention. While a modern condenser microphone is not unduly sensitive to the environment, temperature extremes can be harmful. Exposure to high temperatures can result in gradual and permanent reduction of the output level. Avoid leaving the microphone in the open sun or in areas where temperatures exceed 110° F (43° C) for long periods of time. Extremely high humidity should also be avoided. The microphone shall be mountable in an included instrument adapter or clothing clip. The microphone shall be 0.98" (25.0 mm) long with a diameter of 0.39" (10.0 mm). The microphone weight shall be 0.1 oz (2.8 grams). Finish shall be low-reflectance black. The Audio-Technica AT831b is specified. Frequency Response 10 dB 50 100 200 500 1k 2k Frequency in Hertz LEGEND 12" or more on axis Roll-off 5k 10k 20k Response in dB The microphone element is enclosed in a rugged housing with low-reflectance finish. Internal construction is designed to minimize handling and clothing noise. A 6' (1.8 m) cable is provided between the microphone and power module. A built-in 3-position switch on the power module allows selection of off, on/flat response, or on/low-roll-off. An AT8417 clothing clip and AT8444 guitar adapter are provided, as well as an accessory AT8116 windscreen. The microphone is well protected by a speciallydesigned carrying case. The microphone shall have a permanentlyattached 6' (1.8 m) miniature cable between the microphone and power module. The power module shall house the battery and contain an off/on/low-roll-off switch. The power module shall terminate in a 3-pin XLRM-type connector. AT831b AT831b SPECIFICATIONS† ELEMENT Fixed-charge back plate permanently polarized condenser Cardioid (Unidirectional) 40 -20,000 Hz 80 Hz, 18 dB/octave –44 dB (6.3 mV) re 1V at 1 Pa* –45 dB (5.6 mV) re 1V at 1 Pa* 200 ohms 270 ohms 135 dB SPL, 1 kHz at 1% T.H.D. 121 dB SPL, 1 kHz at 1% T.H.D. 106 dB, 1 kHz at Max SPL 92 dB, 1 kHz at Max SPL 65 dB, 1 kHz at 1 Pa* Off, on-flat, on-roll-off Use only “leakproof” AA/UM3 1.5V battery 0.4 mA typical 1200 hours (alkaline battery) 9-52V DC, 2 mA typical Polar Pattern POLAR PATTERN FREQUENCY RESPONSE LOW-FREQUENCY ROLL-OFF OPEN CIRCUIT SENSITIVITY 0 30 330 300 60 90 270 240 120 150 210 180 SCALE IS 5 DECIBELS PER DIVISION LEGEND 200 Hz 1 kHz 5 kHz 8 kHz XLRM-Type Plug Wiring Low Impedance Balanced PHANTOM BATTERY IMPEDANCE PHANTOM BATTERY MAXIMUM INPUT SOUND LEVEL PHANTOM BATTERY DYNAMIC RANGE (TYPICAL) PHANTOM BATTERY SIGNAL-TO-NOISE RATIO1 SWITCH BATTERY TYPE BATTERY CURRENT BATTERY LIFE PHANTOM POWER REQUIREMENTS WEIGHT (LESS CABLE AND ACCESSORIES) MICROPHONE POWER MODULE DIMENSIONS MICROPHONE POWER MODULE 0.1 oz (2.8 grams) 5.2 oz (147 grams) 0.98" (25.0 mm) long, 0.39" (10.0 mm) dia. 3.27" (83.0 mm) H x 2.48" (63.0 mm) W x 0.87" (22.0 mm) D, not including clip Integral 3-pin XLRM-type Integral 6' (1.8 m), permanently attached between microphone and power module AT8417 clothing clip; AT8444 instrument adapter; AT8530 power module; AT8116 windscreen; battery; protective carrying case OUTPUT CONNECTOR (POWER MODULE) CABLE ACCESSORIES FURNISHED In the interest of standards development, A.T.U.S. offers full details on its test methods to other industry professionals on request. * 1 Pascal = 10 dynes/cm2 = 10 microbars = 94 dB SPL 1 Typical, A-weighted, using Audio Precision System One. † 1 /4 " Phone Plug Wiring Low Impedance Unbalanced RED WIRE WHITE WIRE Optional Accessories: Dimensions TIP SLEEVE SHIELD 0.98" 25.0 mm AT8530 Power Module Dimensions 0.87" 22.0 mm 2.48" 63.0 mm Push Button To Release Cap 0.39" 10.0 mm PUSH 3.27" 83.0 mm • CP8201 line matching transformer (Lo-Z to 50,000 ohms). • AT8202 adjustable in-line attenuator for use with balanced Lo-Z microphones. • AT8314 2-conductor, shielded, vinyl-jacketed, broadcast-type cable with XLRF-type connector at microphone end, XLRM-type connector at equipment end. Available in 10', 20', 25', 30', 50' & 100' lengths. • AT8412 double clothing clip. • AT8414 tie tac. • AT8438 stand adapter. • CP8506 four-channel 48V phantom power supply (AC powered). • AT8801 single-channel 48V phantom power supply (AC powered). SWITCH POWER MODULE audio-technica MADE IN JAPAN Roll-off Flat Off One-Year Limited Warranty OFF Audio-Technica microphones and accessories 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. Prior approval from A.T.U.S. is required for return. This warranty excludes defects due to normal wear, abuse, shipping damage, or failure to use product in accordance with instructions. This warranty is void in the event of unauthorized repair or modification. For return approval and shipping information, contact the Service Department, Audio -Technica U.S., Inc., 1221 Commerce Drive, Stow, Ohio 44224. Except to the extent precluded by applicable state law, A.T.U.S. will have no liability for any consequential, incidental, or special damages; any warranty of merchantability or fitness for particular purpose expires when this warranty expires. This warranty gives you specific legal rights, and you may have other rights which vary from state to state. Outside the U.S.A., please contact your local dealer for warranty details. Audio-Technica U.S., Inc., 1221 Commerce Drive, Stow, Ohio 44224 Audio-Technica Limited, Old Lane, Leeds LS11 8AG England Form No. 0310-0764-07-B/W © 1998 Audio-Technica U.S., Inc. Printed in U.S.A.