GRAS 46BD 1/4 inch CCP Pressure Standard Microphone Set

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GRAS 46BD 1/4" CCP Pressure Standard Microphone Set

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The Industry Leaders—GRAS 46BD has the lowest noise floor of any ¼″ pressure-field microphone

The 40BD is ideal for sound pressure measurements, as well as high frequency and high level pressure measurements. It is suitable for general purpose acoustic measurements in couplers and at boundaries. Regarding temperature range, see the Specifications. Should higher temperature limits be required, we recommend considering the GRAS probe microphones where the microphone and preamplifier can be isolated from the hot source.

Freq range: 5 Hz to 70 kHz
Dyn range: 44 dB(A) to 166 dB
Sensitivity: 1.45 mV/Pa


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Product Overview

Why is high-frequency measurement needed?

Acoustic quality requirements for telecom, audio, PCs and tablets are ever increasing, with a constant trend towards tighter production tolerances and the need to include higher frequencies in testing. The physical properties of smaller microphones not only make them a great solution for meeting those requirements and minimizing error in the data measured on the production line, they are more easily placed on the lines, where a small footprint is critical—smaller microphones can be fitted in smaller test setups.


Is smaller better?

There is no magic microphone that is perfect for all possible measurement scenarios, but the actual physical size of ¼″ microphones provides many benefits. The size-related properties reduce the pressure build-up effect on the diaphragm, but also significantly minimize error when when the sound wave is not 0° incidence and can inherently enable measurements at higher-frequency ranges and pressure levels. And when accounting for real-world conditions and measuring where there are many reflections and disturbances, such as in-cabin, the physical advantages of a ¼″ microphone can greatly increase accuracy and simplify post-processing data. For example, at 20 kHz, a ½″ free-field (FF) mic underrepresents the sound power of a 90° incidence wave by ca. 10 dB—a ¼″ FF mic, only by approx. 3 dB. This results in more accurate data in environments with random angles of incidence where corrections are difficult or impossible to estimate.

Product Features

  • Reduced influence of the angle of incidence
  • Well-suited for high-frequency measurements
  • Minimal footprint for easy placement on a production line
  • Small diaphragms enable the possibility for testing miniature microphones, such as MEMS
  • Reduced influence on measurement environment due to their small size
  • Lowest noise in the industry for high sensitivity, pressure and free field
  • Enables extreme SPL measurement
  • Competitive pricing