Shure SM81 Instrument Microphone  From Shure

High-quality, unidirectional condenser microphone



Retail:  $436.00

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Manufacturer's Description from Shure

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, no cable. Phantom power required.

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

About Manufacturer

Since 1925, musicians and music enthusiasts around the world have chosen Shure with confidence in the unparalleled sound and performance of our products. For forty years and counting, the Shure SM58 has been the most popular vocal microphone in the world, revered for its natural sound and famed durability. Our wireless microphones are synonymous with innovative technology and bulletproof reliability. And our award-winning earphones are redefining the audio experience for the most discerning listeners. But Shure stands for more than quality products. We are passionate about enabling performances that engage, energize and inspire audiences -- performances that help shape the course of history. Shure was there when Elvis stepped into Sun Studios and when JFK vowed to put a man on the moon. We've been on the world's biggest stages, from Live Earth to the Oval Office, ever since. Shure is also passionate about getting it right. We work tirelessly to develop flawless products and support them with the best customer service in the industry. In fact, in everything we do, we are committed to delivering a great audio experience -- because that's the true measure of legendary performance.


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 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)
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
Supply Voltage: 11 to 52 Vdc, positive, pins 2 and 3
Current Drain: 1.2 mA max.
Environmental Conditions
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)
Storage 0 to 95% relative humidity at room temperature (72 degrees to 80 degrees F, 22 degrees to 27 degrees C)
Steel construction with vinyl metallic paint finish and stainless steel screens
See User Guide
Net: 230 grams (8 oz)
Packaged: 740 grams (1 lb 10 oz)





SM81 User Guide

SM81 Spec Sheet (Includes Polar Pattern Graphs)