Hệ thống micro độ nhiễu thấp GRAS 40HT 1/2'' dành cho không gian hạn hẹp

GRAS 40HT 1/2" Lownoise Microphone System for Confined Spaces

Part Number: GRAS 40HT

Category: GRAS Sound & Vibration

Status: Available

Freq range: 10 Hz to 16 kHz
Dyn range: 6.5 dB(A) to 113 dB
Sensitivity: 800 mV/Pa

Sale Price: Liên hệ

0903368648

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The GRAS 40HT ½-inch Lownoise Microphone System for Confined Spaces has specifications similar to GRAS 40HH but is designed for little space applications.

Technology

Introduction

GRAS 40HT can measure sound pressure levels below the threshold of human hearing; and is amply suitable for sound-power measurements on even very quiet products. Its very wide dynamic range permits measurements down to below – 2 dB re.20 µPa (in 1/3-octave bands) from 20 Hz to 20 kHz.

Typical applications and use

40 HT is for low sound pressure measurements and very low sound power measurements.

Design

40HT comprises a special high-sensitive ½-inch Condenser Microphone GRAS 40AH, a ¼-inch High-impedance Preamplifier GRAS 26HG with adapter GRAS GR0010 for the ½-inch microphone, and special Gain and Filter Unit GRAS 26HT.

The Gain and Filter Unit and Microphone are an individually-matched combination. To complete the system, a special single or 10-channel power module (available from GRAS) is required, i.e. GRAS 12HF for single-channel measurements or GRAS 12HM for 1 to 10 channel measurements.

Each channel provides all voltages required for 40HT and polarizing its microphone.

The Gain and Filter Unit GRAS 26HT 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 switchfor 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 the 40HT 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

Frequency range (±1 dB)	Hz	12.5 to 10 k
Frequency range (±2 dB)	Hz	10 to 16 k
Frequency range (±3 dB)	Hz	6 to 20 k
Dynamic range lower limit (microphone thermal noise)	dB(A)	6.5
Dynamic range upper limit	dB	113
Set sensitivity @ 250 Hz (±2 dB)	mV/Pa	800
Polarization voltage		200 V / Traditional
Microphone venting		Rear
Output impedance	Ω	47
Temperature range, operation	°C / °F	–20 to 60 / -4 to 140
Temperature range, storage	°C / °F	-40 to 85 / -40 to 185
CE/RoHS compliant/WEEE registered		Yes/Yes/Yes