1" Low-noise Level Microphone System - Type 40HF

The 1" Low-noise Level Microphone System Type 40HF can measure noise levels well below the threshold of human hearing. It is amply suitable for acoustic measurements on even very quiet products, e.g. disk drives and other computer products, as well as in quiet rooms.

It has a wide dynamic range which enables measurements from below
-10 dBA re. 20µPa (in 1/3-octave bands) from 10 Hz to 10 kHz.

The Type 40HF comprises the following two specially-designed components:

  • a high-sensitive 1" microphone (Type 40EH)
  • a low-noise 1" microphone preamplifier (Type 26HF)
The microphone and its preamplifier are an individually matched combination.
 
The system can be switched to operate either for pressure measurements or free-field measurements.

To complete the measuring system, a special power module is required and is available from G.R.A.S., i.e.

  • Type 12HF for single-channel measurements
    Or
  • Type 12HM for multi-channel (1 to 10) measurements
The chosen power module provides all necessary voltages for powering the preamplifier(s) as well as polarising the microphone(s). It also has a two-position switch for selecting which microphone operation to use, i.e. pressure or free-field.

The following high-quality extension cables are available for the preamplifier:
  • AA0046    3m
  • AA0047    10m
  • AA0048    30m
    Download Product Data: pd_40HF_ver_13_12_04.PDF
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    Specifications Type 40HF (with a power module)
    Nominal sensitivity:

    System: 1.1 V/Pa

     

    Microphone: 110mV/Pa

    Frequency response:

    12.5 Hz – 4 kHz ± 1 dB

     

    10 Hz – 10 kHz ± 2 dB

     

    6 Hz – 12.5 kHz + 2 dB, –3 dB

    Dynamic range:

    –2 dBA to 110 dB re. 20µPa

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    1" Low-noise Level Microphone System - Type 40HF
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    1" Pressure microphone Type 40EU - Laboratory standard
    Technical notes
    TEDS - plug and play
    ¼" TEDS microphones