GRAS 40HH 1/2'' Lownoise Microphone System
Freq range: 10 Hz to 16 kHz
Dyn range: 6.5 dB(A) to 113 dB
Sensitivity: 800 mV/Pa
The GRAS 40HH 1/2" Lownoise Microphone System can measure sound pressure levels down to close to the threshold of human hearing; and is amply suitable for use in sound-power measurements on even very quiet products. Its very wide dynamic range permits measurements down to 6.5 dB re. 20 μPa (in 1/3-octave bands) from 20 Hz to 20 kHz.
Technology
Typical applications and use
- Very Low Sound pressure measurements
- Low noise product measurements
- Sound power measurements at low sound pressure levels
- Measurements on hard-disk drives, computerproducts, quiet rooms etc.
The 40HH comprises:
- a special high-sensitive 1/2" GRAS 40AH Condenser Microphone
- a special 1/2" GRAS 26HH Lownoise Preamplifier
The preamplifier and microphone are an individually matched combination. To complete the system, a special single or 10-channel power module is required and is available, i.e. GRAS 12HF for single-channel measurements or GRAS 12HM for multi-channel measurements.
The chosen power module provides all necessary voltages for powering the preamplifier(s) as well as polarizing the microphone(s).
Preamplifier
The GRAS 26HH Preamplifier has a built-in overload indicator (which is repeated on the chosen power supply) and a frequency correction facility for both pressure-microphone operation as well as free field microphone operation.
Microphone
The GRAS 40AH Microphone is an externally polarized microphone with a specially reduced inherent noise floor in order to achieve a high dynamic range and wide frequency range. Its diaphragm is specially tuned to yield high sensitivity coupled with low internal-noise generation.
Frequency Response and Noise Floor
The chosen power supply has a two-position switch for selecting which microphone operation to use, i.e.pressure or free-field. A typical free-field response for an angle of incidence of 0° is shown in the data sheet when GRAS 40HH is switched to free-field operation. Also shown is a complete low-noise measuring system, a typical noise floor in 1/3-octave bands for both the linear and A-weighted cases.
Specifications
Typical frequency response
Typical noise floor shown in 1/3-octave bands - linear and A-weighted cases
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
Ordering info
Included items
| GRAS 40AH |
High sensitive 1/2" microphone |
| GRAS 26HH |
Lownoise 1/2" preamplifier |
Optional items
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1-Channel Power Module for Lownoise Systems |
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10-Channel Power Module for Lownoise Systems |
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Windscreen for 1" Microphones |
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Pistonphone, Class 1 |
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Pistonphone Coupler |
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| GRAS AL0006 |
Tripod |
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Adjustable, high quality, stainless steel tripod adapter |
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Dehumidifier for 1” microphones |
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3 m LEMO 7-pin - LEMO 7-pin Cable for Low-noise measuring system |
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10 m LEMO 7-pin - LEMO 7-pin Cable for Low-noise measuring system |
GRAS Sound & Vibration reserves the right to change specifications and accessories without notice.
