• This microphone requires phantom power and performs best with a 48 Vdc supply (IEC-61938). However, it will operate with slightly decreased headroom and sensitivity with supplies as low as 11 Vdc. Most modern mixers provide phantom power. You must use a balanced microphone cable: XLR-to-XLR or XLR-to-TRS..
• 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.
• Rugged steel construction for durability. Field-usable over wide range of temperature and humidity conditions..
• Cardioid condenser instrument microphone offers a wide frequency response and low self-noise. Features include flat response curve, low noise and high output clipping level, low distortion over a range of load impedances, and low RF susceptibility..

Product Description ------------------- The Shure SM81 is a high-quality, unidirectional condenser microphone designed for studio , 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. POWER REQUIREMENTS NOTE: This microphone requires phantom power and performs best with a 48 Vdc supply (IEC-61938). However, it will operate with slightly decreased headroom and sensitivity with supplies as low as 11 Vdc. Most modern mixers provide phantom power. You must use a balanced microphone cable: XLR-to-XLR or XLR-to-TRS. .com ---- Built to withstand the rigors of regular stage and studio use, the Shure SM81 unidirectional condenser microphone is a great choice for studio , broadcasting, and sound reinforcement. Its wide frequency response, low noise characteristics, and low RF susceptibility make it a perfect match for applications involving acoustic instruments, especially guitar, piano, and cymbals. Ruggedly constructed, the SM81 operates on phantom power and performs over a wide range of temperatures and humidity conditions. It comes with a swivel adapter, attenuator-switch lock, foam windscreen, and case for carrying and storage. ------------ Key Features ------------ Frequency response. Polar pattern.* 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 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 H: z 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. * Case: Steel construction with vinyl metallic paint finish and stainless steel screens * Weight: 8 ounces