Shure : SM81
Description
The Shure SM Microphones Series
SM-81 is a high-quality, unidirectional condenser microphone designed for studio recording, broadcasting, and sound reinforcement. The SM 81 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.
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→ 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 conditionsSpecifications
| 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 |
| Selectable low-frequency response | flat, 6 or 18 dB/octave rolloff |