Shure Beta 181/BI Ultra-Compact Side-Address Condenser Instrument Microphone with Bidirectional Polar Pattern Capsule


About Shure BETA 181/BI

The Shure Beta 181/BI is an ultra-compact, small-diaphragm side-address condenser microphone, designed for discreet placement and control in live and studio environments. Featuring interchangeable cardioid, supercardioid, omnidirectional and bidirectional capsule options for superior versatility, the small diaphragm design provides superior audio with consistent, textbook polar responses in a form factor small enough to get close to the source in the tightest conditions.

Shure BETA 181/BI Features

  • BETA 181/BI (bi-directional) for mono drum overhead, dual instrument sound source applications, Blumlein stereo technique (pair of Beta 181/BI)
  • Interchangeable polar pattern capsules attach to a compact preamplifier with integrated XLR connections for the ultimate in low-profile application flexibility
  • Precision-engineered, compact side-address design features innovative locking ring to provide secure connection between capsule and preamplifier
  • Frequency response tailored for wide dynamic range applications for use in high SPL environments
  • Furnished with stand adapter, windscreen and carrying case (carrying case will securely protect up to four polar pattern capsules)

Shure BETA 181/BI Specifications

Cartridge Type
Electret Condenser
Polar Pattern
Frequency Response
20Hz to 20kHz
Output Impedance
110 ohm
-51.0 dBV/Pa (2.6 mV) (open circuit voltage, @ 1 kHz, typical)
Maximum SPL
2500 ohm load: 156.0 dB SPL
1000 ohm load: 153.5 dB SPL (1 kHz at 1% THD)
Signal-to-Noise Ratio
71.0 dB
Dynamic Range
2500 ohm load: 133.0 dB
1000 ohm load: 130.5 dB
Clipping Level
2500 ohm load: 10.5 dBV
1000 ohm load: 7.5 dBV (@ 1 kHz, 1% THD)
Self Noise
23.0 dB SPL-A (equivalent SPL, A-weighted, typical)
Common Mode Rejection
=55 dB
Positive pressure on diaphragm produces positive voltage on pin 2 with respect to pin 3
Power Requirements
11-52 V DC phantom power (IEC-61938) 2.4 mA, maximum
145 g (5.1 oz)
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