Shure SM81-LC Condenser Microphone

Key Features

Frequency response.

Polar pattern.

• Flat response curve for accurate reproduction of sound sources
• Low noise and high output clipping level
• Low distortion over a wide range of load impedances
• Cardioid polar pattern, uniform with frequency and symmetric about axis, providing maximum rejection and minimum coloration of off-axis sounds
• Low RF susceptibility
• Selectable low-frequency response: flat, 6 or 18 dB/octave rolloff
• 0 dB/10 dB lockable attenuator switch
• Phantom powering (DIN 45 596 voltages of 12 to 48 Vdc)
• Rugged steel construction for durability
• Field-usable over wide range of temperature and humidity conditions

Specifications

• Type: Condenser (electret bias)
• Frequency Response: 20 to 20,000 Hz
• Polar Pattern: Cardioid (unidirectional) response-uniform with frequency, symmetrical about axis
• Output Impedance: Rated at 150 ohms (85 ohms actual)

  Recommended minimum load impedance: 800 ohms (May be used with loads as low as 150 ohms with reduced clipping level)

• Output Configuration and Connector: Balanced, transformer-coupled output; male XLR connector
• Sensitivity (at 1,000 Hz): Open Circuit Voltage: -45 dBV/Pascal (5.6 mV); (1 Pascal = 94 dB SPL)
• Clipping Level (at 1,000 Hz): 800 ohm Load: -4 dBV (0.63 V); 150 ohm Load: -15 dBV (0.18 V)
• Total Harmonic Distortion Less than 0.5% (131 dB SPL at 250 H: z into 800 ohm load)
• Maximum SPL (at 1,000 Hz):
  • 800 ohm load: 136 dB (attenuator at 0) 146 dB (attenuator at -10)
  • 150 ohm load: 128 dB (attenuator at 0) 138 dB (attenuator at -10)
• Hum Pickup: -3 dB equivalent SPL in a 1 mOe field (60 Hz)
• Self-Noise (equivalent sound pressure levels; measured with true rms voltmeter): 16 dB typical, A-weighted; 19 dB typical, weighted per DIN 45 405
• Signal-to-Noise Ratio: 78 dB (IEC 651)* at 94 dB SPL

  *S/N ratio is difference between 94 dB SPL and product's equivalent self noise (SPL A-weighted).

• Overvoltage and Reverse Polarity Protection:
  • Max. external voltage applied to pins 2 and 3 with respect to pin 1: +52 Vdc
  • Reverse polarity protection: 200 mA max. (diode-clamped)
• Polarity: Positive pressure on diaphragm produces positive voltage on pin 2 relative to pin 3
• Cartridge Capacitance: 54 pF
• Low Frequency Response Switch Positions: Flat; -6 dB/octave below 100 Hz; -18 dB/octave below 80 Hz
• Attenuator Switch Positions (Lockable): 0 or -10 dB
• Power:
  • Supply Voltage: 11 to 52 Vdc, positive, pins 2 and 3
  • Current Drain: 1.2 mA max.
• Case: Steel construction with vinyl metallic paint finish and stainless steel screens
• Weight: 8 ounces