The SM137 is a versatile, flat-response cardioid condenser probe microphone.
The SM137 has an ultra-thin diaphragm for a frequency response that combines a smooth high-end with a tight, controlled low-end and a 15db pad for natural sound reproduction in both acoustic and high volume performance applications.
Cartridge Type Permanently Biased Condenser
Frequency Response 20 to 20,000 Hz
Directional Polar Pattern Cardioid
Output Impedance 150 ohms (actual)
Attenuation Switch 0 dB or 15 dB attenuation
Phantom Power 48 Vdc +/- 4 Vdc (IEC-268-15/DIN 45 596), positive pins 2 and 3
Current Drain 5.2 mA typical at 48 Vdc
Common Mode Rejection >50 dB, 20 Hz to 20 kHz
Polarity Positive pressure on diaphragm produces positive voltage on output pin 2 relative to pin 3
Dimensions and Weight 24 mm (0.950 in.) diameter 162 mm (6.375 in.) long 195 grams (6.9 oz.)
Sensitivity (typical, at 1000 Hz; 1 Pa = 94 dB SPL) -41 dBV/Pa
Self-noise (typical, equivalent SPL; A-weighted (IEC 651)) 19 dB
Maximum SPL@ 1000 Hz 5000 ohms load (Attenuator on): 150 (165 dB) 2500 ohms load (Attenuator on): 144 (159) dB 1000 ohms load (Attenuator on): 139 (154 dB)
Output Clipping Level* 5000 ohms load: 15 dBV 2500 ohms load: 9 dBV> 1000 ohms load: 3 dBV *20 Hz to 20 kHz; THD < 1%. THD of the microphone preamplifier when applied input signal is equivalent to the cartridge output at specified SPL.
Dynamic Range (Attenuator On) 5000 ohms load: 133 (136) dB 2500 ohms load: 128 (130 dB) 1000 ohms load: 122 (125) dB
Signal to Noise Ratio** 75 dB **S/N ratio is difference between 94 dB SPL and equivalent SPL of self-noise A-weighted.
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