Cardioid Condenser Microphone
The ATM31a is a cardioid condenser mic with an electret capsule. It was presented as an all-purpose studio or field microphone, and could be powered via phantom power or an AA/UM3 battery.
Note that the specs change if you run the mic from a battery rather than phantom power. Using a battery:
- Impedance changes from 200 ohms to 270 ohms
- Dynamic range drops from 113 dB to 99 dB
- Sensitivity changes from -44dB (6.3 mV) to -45dB (5.6 mV)
The ATM31a is a revision to the original ATM31 (circa 1981). The newer model has a wider frequency response, higher sensitivity, and can be used with phantom power (meaning, the battery is not required). The published polar and frequency-response graphs are different, but Audio-Technica has not described the changes made to the mic’s components.
The Audio-Technica ATM31a is also known as: ATM31, ATM-31, ATM-31a.
The mic was released in 1981.
|Frequency Response - CardioidClick Graph to Compare!|
|Pickup Patterns||Pads & Filters|
(6.3 mV/Pa; 30 - 20,000 Hz)
| Diameter n/a
||200 Ohms (Low)||Max SPL: 137 dB
Self-noise: 14.0 dB(A)
|200g (7.05oz)||193mm (7.60'')||50mm (1.97'')||
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