Shure SM81 Unidirectional Cardioid Condenser Microphone

SM81 Unidirectional Cardioid Condenser Microphone description:

The Shure Model SM81 is a high-quality, unidirectional condenser microphone designed for studio recording, broadcasting, and sound reinforcement. Its wide frequency response, low noise characteristics, and low RF susceptibility have made it a standard for applications involving acoustic instruments, especially guitar, piano, and cymbals.

The SM81 is ruggedly constructed. It operates on phantom power and performs over a wide range of temperatures and humidity conditions. It is supplied with a swivel adapter, attenuator-switch lock, foam windscreen, and case for carrying and storage. Other accessories are available.

Features:

• 20 Hz to 20 kHz frequency response
• 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 ohms Load –4 dBV (0.63 V), 150 ohms Load –15 dBV (0.18 V)
• Total Harmonic Distortion: Less than 0.5% (131 dB SPL at 250 Hz into 800 ohms load)
• Maximum SPL (at 1,000 Hz): 800 ohms load 136 dB (attenuator at 0)/146 dB (attenuator at –10) OR 150 ohms 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 OR 19 dB typical, weighted per DIN 45 405
• Signal-to-Noise Ratio: 78 dB (IEC 651) at 94 dB SPL
• Polarity: Positive pressure on diaphragm produces positive voltage on pin 2 relative to pin 3
• 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
• Operating Temperature: – 6.7degrees C to 49 degrees C
• Case: Steel construction with vinyl metallic paint finish and stainless steel screens
• Weight: Net 230 grams (8 oz)/Packaged 740 grams (1 lb 10 oz)