Shure BETA91A Half-Cardioid Condenser Microphone

en July 24 , 2019
General Description
The Shure Beta 91A is designed for use with kick drums, piano and other traditional low frequency applications. Tailored for bass-heavy environments, this microphone features a powerful low frequency response and integrated preamplifier and XLR connection for easy setup and minimal stage clutter. The Beta 91A combines superior attack and punch for studio-quality sound, even at extremely high sound pressure levels (SPLs).


General Rules for Use
This table lists the most common applications and placement techniques. Keep in mind that microphone technique is largely a matter of personal taste; there is no one "correct" microphone position.

Applications and Placement
Location and room acoustics strongly affect the sound quality of microphones. To achieve the best overall sound for a particular application, it may be necessary to experiment with microphone placement and room treatments.
Application Suggested Microphone Placement Tone Quality
Kick Drum Inside drum, on a pillow or other cushioning surface, 25 to 152 mm (1 to 6 in.) from beater head. Full, natural sound.
Contour switch activated; 25 to 152 mm (1 to 6 in.) from beater head. Sharp attack; maximum bass 'punch.'
Piano Mount microphone on underside of lid over lower treble strings. Experiment with lid height and placement to hammers for desired sound. Bright, well-balanced, strong attack; excellent isolation.
Mount microphone vertically on the inside of the piano frame, near the apex of the piano`s curved wall. Full, natural; excellent isolation and minimal hammer and damper noise.

Mounting the Microphone
If desired, attach the microphone to a prepared surface using the mounting holes on the bottom of the microphone.
Half-cardioid Polar Pattern
This boundary microphone has a cardioid polar pattern in the hemisphere above the mounting surface. Keep sound sources within a 60� range above this surface.

Contour Switch
A two-position switch on the bottom of the microphone lets you selectively filter the low-mid frequency response without additional tools. Use this filter to enhance the attack and clarity of bass-heavy instruments.
Flat response: Provides the most natural sound in most applications.
Low-Mid Scoop: This setting tailors the microphone frequency response to provide a strong 'punch' in the low frequencies, and plenty of attack in the higher frequencies.

Load Impedance
Maximum SPL capability, output clipping level, and dynamic range vary with the input load impedance of the preamplifier to which you connect the microphone. Shure recommends a minimum input load impedance of 1000 Ω. Most modern microphone preamplifiers meet this requirement. Higher impedance results in better performance for these specifications.

Power Requirements
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.

Furnished Accessories
Zippered Carrying Bag 95A2314

Optional Accessories
25 foot (7.5m) Triple-Flex ® Microphone XLR Cable with Switchcraft connectors C25E

Replacement Parts
>Cardioid CartridgeRPM98A/C

Type: Electret Condenser
Frequency Response: 20 to 20,000 Hz
Polar Pattern: Half-cardioid (cardioid in hemisphere above mounting surface)
Output Impedance: EIA rated at146 Ω
Sensitivity: at 1kHz,open circuit voltage -48.5 dBV/Pa(3.8 mV)[1]
Maximum SPL: 1 kHz at 1% THD[2]

2500 Ω load155  dB
1000 Ω load151  dB

Signal-To-Noise Ratio[3]: 64.5  dB
Dynamic Range: at 1kHz
2500 Ω load125.5  dB
1000 Ω load121.5  dB

Clipping Level: 20 Hz to 20 kHz, at 1% THD
2500 Ω load12.5  dB
1000 Ω load7.5  dB
Self Noise
equivalent SPL, A-weighted, typical: 29.5  dB SPL-A
Common Mode Rejection: (20  Hz to 200 kHz) ≥55  dB
Frequency Contour Switch: 7 dB of attenuation centered at 400 kHz
Power Requirements: 11�52  V DCphantom power[4], 5.4 mA
Polarity: Positive pressure on diaphragm produces positive voltage on pin 2 with respect to pin 3
Weight: 470 g(16.6 oz.)
Connector: Three-pin professional audio (XLR), male, balanced
[1] 1 Pa=94 dB SPL
[2] THD of microphone preamplifier when applied input signal level is equivalent to cartridge output at specified SPL
[3] S/N ratio is the difference between 94 dB SPL and equivalent SPL of self-noise, A-weighted
[4] All specifications measured with a 48 Vdc phantom power supply. The microphone operates at lower voltages, but with slightly decreased headroom and sensitivity

This product meets the Essential Requirements of all relevant European directives and is eligible for CE marking.
The CE Declaration of Conformity can be obtained from: www.shure.com/europe/compliance
Authorized European representative:
Shure Europe GmbH
Headquarters Europe, Middle East & Africa
Department: EMEA Approval
Jakob-Dieffenbacher-Str. 12
75031 Eppingen, Germany
Phone: 49-7262-92 49 0
Fax: 49-7262-92 49 11 4
Email: [email protected]
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