Operation, Specifications, Furnished Accessories

OPERATION

Power

The SM87A requires phantom power. This may be supplied to the microphone from an external power supply (such as the Shure model PS1A) or directly from preamplifiers, mixers, or consoles with built-in phantom power. Suitable sources should provide 11 to 52 Vdc phantom voltage.

Proximity Effect

Unidirectional microphones such as the SM87A progressive- ly boost bass frequencies by 10 to 15 dB at 100 Hz when the microphone is at a distance of about 6 mm (1/4 in.) from the sound source. This phenomenon, known as proximity effect, can be used to create a warmer, more powerful sound. To pre- vent explosive low frequency sound during close-up use, the SM87A bass response gradually rolls off. This provides greater control and helps the user take advantage of proximity effect.

Wind Noise

The SM87A has an integral wind and pop filter which provides excellent protection against most wind and breath noise. Under adverse conditions, such as high winds or close proximity to a “problem” vocalist, the optional foam windscreen can be used.

Impedance

A minimum load impedance of 800 ohms should be used for maximum signal handling and minimum distortion. The load may be as low as 150 ohms, but a reduction in output signal strength and output clipping level will result.

SPECIFICATIONS

Cartridge Type

Condenser (electret bias)

Frequency Response

50 to 20,000 Hz (see Figure 2)

Polar Pattern

Supercardioid (see Figure 3)

Output Impedance

Rated at 150 ohms (100 ohms actual ±20%) Recommended minimum load impedance: 800 ohms

Sensitivity (at 1,000 Hz)

Open Circuit Voltage . . . . . . . . . . . . . . . –52.5 dBV/Pa (2.4 mV) (1 Pa = 94 dB SPL)

Clipping Level (at 1,000 Hz)

1000 ohm Load . . . . . . . . . . . . . . . . . . . . . . . . . . –6 dBV (0.5 V)

Maximum SPL (at 1,000 Hz)

140.5 dB (0.25% THD, 1000 ohm load)

Self-Noise(equivalent sound pressure level; measured with true rms voltmeter)

24 dB typical, A-weighted

26 dB typical, weighted per DIN 45 405

Dynamic Range

116.5 dB (maximum SPL to A-weighted noise level)

Signal-to-Noise Ratio

70 dB at 94 dB SPL (IEC 651)*

Polarity

Positive pressure on diaphragm produces positive voltage on pin 2 relative to pin 3

Power

Phantom Supply Requirement . . . . . . . . 11 to 52 Vdc, positive at both pins 2 and 3 Current Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0 to 1.2 mA

Connector

Three–pin (XLR) professional audio

Case

Aluminum construction with steel grille and satin black finish

Dimensions

See Figure 4

Net Weight

200 grams (7 oz)

*S/N ratio is difference between 94 dB SPL and equivalent SPL of self– noise A-weighted.

CERTIFICATION

Eligible to bear CE Marking. Conforms to European EMC Directive 89/336/EEC. Meets applicable tests and perfor- mance criteria in European Standard EN55103 (1996) parts 1 and 2, for residential (E1) and light industrial (E2) environments.

FURNISHED ACCESSORIES

Swivel Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A25D Carrying/Storage Bag . . . . . . . . . . . . . . . . . . . . . . . . . 26A13

OPTIONAL ACCESSORIES

Phantom Power Supply . . . . . . . . . . . . . . . . . . . . . . . . PS1A Isolation Mount . . . . . . . . . . . . . . . . . . . . . . . . A55M, A55HM Windscreen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A85WS Cable (7.6 m [25 ft]) . . . . . . . . . . . . . . . . . . . . . . . . . . . . C25F

REPLACEMENT PARTS

Screen and Grille . . . . . . . . . . . . . . . . . . . . . . . . . . . RK214G

Cartridge and Shock Mount . . . . . . . . . . . . . . . . . . . . . R128

Replacement Amplifier Assembly . . . . . . . . . . . . . . . RK356

TROUBLESHOOTING

If problems arise, test the phantom power source and con- nectors before calling for service. The microphone will not operate without phantom power.

Check the voltage on pins 2 and 3 of the XLR connector going to the microphone. The voltage at pins 2 and 3 with ref- erence to pin 1 should be between 11 and 48 Vdc.

For additional service or parts information, please contact Shure’s Service department at 1–800–516–2525. Outside the United States, please contact your authorized Shure Service Center.