CCP Rugged Pressure Microphone GRAS 147AX 3.15-20kHz

Introduction

• 147AX is a rugged surface-mounted pressure microphone optimized for engine compartment testing in the automotive industry. It combines the high precision and stability of a laboratory microphone with a high level of ruggedness, including the ability to function properly in the most challenging environment with vibrations, oil mists, water spray and dirt and dust – and high temperatures up to 125°C.
• With the 147AX it is now possible to introduce a considerable improvement in the way acoustic engine compartment measurements can be done. The small form factor makes it possible to place the microphones where size constraints previously prevented so. Also, the microphone system’s resistance to heat, dirt, oil mists and vibrations makes it possible to make hot engine tests under real-life conditions. A novel mounting system (MagMountTM) makes it easy to mount precisely and ensures very good repeatability, even after full dismounting of the microphones.

Design

• Like other members of the GRAS family of microphones for automotive NVH testing, the 147AX is designed to perform optimally under the rough conditions encountered in automobile NVH testing.
• The most important design features to accomplish this are:

Vibration resistant and rugged

• A new design of the preamplifier and other internal parts makes it resilient to shock and vibrations.  It functions well under conditions with vibrations and g-forces from uneven road surfaces and other sudden directional shifts as encountered in real-life driving tests.
• The most vulnerable part of any condenser microphone is the diaphragm. In the 147AX a more robust type is used. It can be replaced during repair, keeping maintenance costs at a minimum.

Temperature resistant

• The microphone set works properly up to temperatures of 125°C/257°F. The integrated cable is a high-temperature type. This means that the 147AX can be mounted closely to heat-emitting components and will provide reliable data in all realistic use scenarios.

Effective protection

• The microphone-preamplifier assembly is effectively sealed against moisture and is IP67 rated. Special protective water and oil repellent coating adds further protection and makes it easy to clean.
• The microphone diaphragm is protected by a grid that has a comprehensive multi-layer filtering system that ensures good protection against high-velocity particles and prevents dirt and dust from polluting the microphone. Provided that the protective grid is replaced at appropriate intervals this system ensures that the microphone will function properly even in very dirty conditions. The filter also protects the diaphragm against water splashes and oil mists.
• A customized windscreen is available. Even when turbulence is not a problem it can be used for further protection.