GRAS 40HL 1/2” LEMO Low-noise Microphone System

Typical applications and use

• Measurements at very low sound pressurelevels
• Measurements on hard-disk drives, computerproducts, anechoic rooms, quiet rooms, etc
• Sound-power measurements at low levels

Design

The 40HL comprises a special high-sensitive 1/2″ free-field measurement microphone and an integrated 1/2″ low-noise preamplifier. In combination, they connect to most high-quality input modules with LEMO 1B connector.

It complies with IEC 61672 class 1.

Preamplifier

The preamplifier, a true 1/2″ low-noise amplifIer with LEMO 1B connector, has a built-in compensation filter for free-field microphones.

Microphone

The 1/2″ microphone is an externally-polarized free field 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.

TEDS

The preamplifier of the 40HL has TEDS according to IEEE 1451.4. If your measurement platform supports TEDS you can read and write data like properties and calibration data.

Operating 40HL

For holding the microphone, you can order tripods and for level calibration of you need a pistonphone and Calibration Adapter attenuating the pistonphone signal to 94 dB re. 20 µPa. See the tab Ordering info.