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CardioidAudio-Technica AT4021

Cardioid Pencil Condenser Microphone

The AT4021 is a cardioid electret FET condenser with a small-diaphragm capsule designed for flat, extended frequency response.

The mic’s published frequency-response graph shows an essentially flat response from 20Hz - 20kHz, with a gentle -2dB dip at 80Hz, a sharp rise to +2dB at 6500Hz, and a gentle presence peak to +2dB above 10kHz.

The AT4021 capsule uses a single 16.3mm diaphragm made of 2-micron PPS. (Polyphenylene Sulfide, or PPS, is a plastic resin known for its thermal and dimensional stability, as well as its resistance to corrosion.) A modified version of this capsule can be found in the XY-stereo mic AT8022.

The mic was released in 2008, along with a companion omni mic, the AT4022.

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The mic was released in 2008.


Frequency Response - CardioidClick Graph to Compare!
AT4021 Cardioid Frequency Response Chart
Pickup Patterns Pads & Filters
Cardioid (19.9 mV/Pa; 20 - 20,000 Hz)
  • Pad: -10dB (Via Switch)
  • Filter: HPF: -12dB/octave @ 80Hz (Via Switch)
Capsule Dimensions Impedance SPL/Noise
Diaphragm diameter: 16.3mm
Capsule diameter: 21mm
Diaphragm gauge: 2 microns
250 Ohms (Low) Max SPL: 156 dB
Self-noise: 14.0 dB(A)
Weight Length Max Diameter Interface(s)
119g (4.20oz) 144mm (5.67'') 21mm (0.83'')
  • 3-pin XLR male (1)
Power Specifications
  • Requires phantom power
  • Phantom voltage: 48v

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