Shure SM81 Condenser Instrument Microphone

The legendary SM81 is an industry-standard, flat-response cardioid condenser microphone, featuring a wide frequency response and low self-noise. Highly versatile, the SM81’s renowned sonic accuracy is a constant choice around the world for acoustic stage and studio performance, including guitar, piano and drum overhead applications.

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.

• 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

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.

Type

• Condenser

Frequency Response

• 20 to 20,000 Hz

Polar Pattern

• Cardioid

Sensitivity (at 1,000 Hz)

• Open Circuit Voltage: -45 dBV/Pascal (5.6 mV) (1 Pa = 94 dB SPL)

Impedance

• Rated at 150 ohms (85 ohms actual)
• Recommended minimum load impedance: 800 ohms

Output Clipping Level

• 800 ohm Load: -4 dBV (0.63 V)
• 150 ohm Load: -15 dBV (0.18 V)

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)

Self-Noise

• 16 dB typical, A-weighted
• 19 dB typical, weighted per DIN 45 405

Hum Pickup

• -3 dB equivalent SPL in a 1 mOe field (60 Hz)

Signal-to-Noise Ratio

• 78 dB (IEC 651)* at 94 dB SPL
• S/N ratio is difference between 94 dB SPL and equivalent SPL of self– noise 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

Power

• 11 to 52 vdc, 1.2 mA

Case 

• Steel construction with vinyl metallic paint finish and stainless steel screens

Connector 

• Three-pin professional audio connector (male XLR type)

Net Weight 

• 230 grams (8 oz)

Dimensions 

• 212 mm (7-9/16 in.) L x 23.5 mm (2 in.) W at the widest point