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.

Features:

Capsule Type: Condenser
Pad: 15dB