Shure - Microphones - SM81 Instrument Microphone

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.

SM81-LC with windscreen, without cable. Phantom power required.

One of the world's greatest studio condenser mics, the SM81 is a flat response mic with a selectable, low-frequency response switch -- flat, 6dB/octave roll-off or 18dB/octave roll-off -- and a 10dB attenuator. Cardioid, Condenser.

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. Other accessories are available.

0 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

Type

Condenser (electret bias)

Frequency Response

20 to 20,000 Hz

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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 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.

Environmental Conditions

Temperature:: Storage: -29 degrees to 74 degrees C (-20 degrees to 165 degrees F); Operating: -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