SM81 Instrument Microphone

The Shure 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 furnished with a swivel adapter, attenuator-switch lock, foam windscreen, and case for carrying and storage

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 Hz 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 :: 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.
• Storage Temperature :: -29 degrees to 74 degrees C (-20 degrees to 165 degrees F)
• Operating Temperature :: -6.7 degrees to 49 degrees C (20 degrees to 120 degrees F)
• Humidity :: Storage 0 to 95% relative humidity at room temperature (72 degrees to 80 degrees F, 22 degrees to 27 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)

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

Application

Instrument microphone designed for studio recording, broadcasting, and sound reinforcement