Features:
- Specially engineered to meet the most critical acoustic requirements of professional recording, broadcast and sound reinforcement
- Low self-noise perfectly suited for the most sophisticated recording equipment
- Low-mass diaphragm improves transient response, increases response bandwidth and reduces handling and mechanical noise transfer
- Cardioid polar pattern reduces pickup of sounds from the sides and rear, improving isolation of desired sound source
- Rugged design and construction for reliable performance
- Integral 80 Hz high-pass filter switch and 10 dB pad switch
- State-of-the-art design and manufacturing techniques ensure compliance with A-T's stringent consistency and reliability standards
The AT4021 is a fixed-charge condenser microphone with a cardioid polar pattern. It is designed to meet the demands of critical studio and live applications. The microphone requires 48V phantom power for operation. The cardioid polar pattern of the microphone is more sensitive to sound originating directly in front of the element, making it useful for controlling feedback and reducing pickup of unwanted sounds. The output of the microphone is a 3-pin XLRM-type connector. The microphone is equipped with a switchable 10 dB pad and a switch that permits choice of flat response or low-frequency roll-off (via integral 80 Hz high-pass filter). The microphone is enclosed in a rugged housing. The included AT8405a stand clamp permits mounting on any microphone stand with 5/8"-27 threads. A windscreen and a protective carrying case are also included.
Operation and Maintenance
The AT4021 requires 48V phantom power for operation. Output is low impedance (Lo-Z) balanced. The signal appears across Pins 2 and 3; Pin 1 is ground (shield). Output phase is "Pin 2 hot"- positive acoustic pressure produces positive voltage at Pin 2. To avoid phase cancellation and poor sound, all mic cables must be wired consistently: Pin 1-to-Pin 1, etc. An integral 80 Hz high-pass filter provides easy switching from a flat frequency response to a low-end roll-off. The roll-off position reduces the pickup of low-frequency ambient noise (such as traffic, air-handling systems, etc.), room reverberation and mechanically coupled vibrations. To engage the high-pass filter, slide the switch toward the "bent" line. The microphone is also equipped with a switchable 10 dB pad that lowers the microphone's sensitivity, thus providing higher SPL capability for flexible use with a wide range of users and system configurations. To engage the 10 dB pad, slide the switch toward the -10 position. Avoid leaving the microphone in the open sun or in areas where temperatures exceed 110° F (43° C) for extended periods. Extremely high humidity should also be avoided.
Architect's and Engineer's Specifications
The microphone shall be a fixed-charge condenser. It shall have a cardioid polar pattern with a uniform 120° angle of acceptance and a frequency response of 20 Hz to 20,000 Hz. The microphone shall operate from an external 48V DC phantom power source. It shall be capable of handling sound input levels up to 146 dB (156 dB with 10 dB pad) with a dynamic range of 132 dB. Nominal open-circuit output voltage shall be 19.9 mV at 1V, 1 Pascal. Output shall be low impedance balanced (250 ohms). The output of the microphone shall be a 3-pin XLRM-type connector. The microphone shall be equipped with a switchable 10 dB pad and a switch that permits choice of flat response or 80 Hz low-frequency roll-off. The microphone shall be 144.0 mm (5.67") long and have a diameter of 21.0 mm (0.83"). Weight shall be 119 grams (4.2 oz). The microphone shall include a stand clamp, a windscreen and a protective carrying case. The Audio-Technica AT4021 is specified.
For more information, please see 
Data Sheet
