The total acoustical sound power emitted from a sound source is effectively determined from sound pressure measurements performed in an anechoic chamber as described in a number of ISO standards. The G.R.A.S. 67HA 1 m LEMO hemisphere kit complies with the ISO 3744, 3745 and 3746 (ANSI S12.54, S12.55, S12.56) standards and comes with 4, 10 or 20 G.R.A.S. microphone sets. The GRAS 67HA 1 m LEMO hemisphere kit is used by manufacturers in a number of industries to determine the sound power levels of their devices.
The hemisphere structure is made portable to achieve a high degree of freedom of location. This, combined with the easy, toolless assembly in minutes, enables you to save expensive anechoic chamber time and to offer on-site sound power diagnostics. Further, the hemisphere supports fast positioning and access to the device under test (DUT).
Depending on your choice of configuration, the G.R.A.S. 67HA 1 m LEMO hemisphere kit accomodates for 4, 10 or 20 positions that are clearly marked to ease the mounting and maintain measurement repeatability.
The hemisphere kit is also available as a 2 m measurement radius, G.R.A.S. 67HB 2 m LEMO.
Typical applications & use
Depending on the size and the emitted acoustic level of the device under test (DUT), the G.R.A.S. 67HA 1 m LEMO hemisphere kit allows for sound power measurements on everything from small sized personal electrics to office machines and IT products, household appliances, power tools and smaller engines. The only restriction - according to the standards that apply - is, that the characteristic dimension of the DUT may be no more than half the measurement radius.
The G.R.A.S. 67HA 1 m LEMO hemisphere kit is available with 4, 10 or 20 microphone sets to suit your type of input module along with dynamic specifications for your application.
- ISO 3746:2010 (ANSI S12.56), 4 Channels
- 67HA-01 LEMO Hemisphere kit
- ISO 3744:2010 (ANSI S12.54), 10 Channels
- 67HA-02 LEMO Hemisphere kit
- ISO 3745:2012 (ANSI S12.55), 20 Channels
- 67HA-03 LEMO Hemisphere kit
The G.R.A.S. 67HA 1 m LEMO hemisphere kit comes with 4, 10 or 20 G.R.A.S. microphone sets that can be connected directly to all professional measurement systems. If your system platform supports intelligent transducers according to IEEE 1451.4 (TEDS), the system can be set up to identify the microphone properties and position in the array.
The microphone sets included are delivered with individual calibration charts including sensitivity values and frequency responses. These sensitivity values can be used directly in your system setup.
Quality & warranty
All G.R.A.S. microphones are made of high-quality materials that will ensure life-long stability and robustness. The microphones are all assembled in verified clean-room environments by skilled and dedicated operators with many years of expertise in this field. The microphone diaphragm, body, and improved protection grid are made of high-grade stainless steel, which makes the microphone resistant to physical damage, as well as corrosion caused by aggressive air or gasses. This, combined with the reinforced gold-plated microphone terminal which guarantees a highly reliable connection, enables G.R.A.S. to offer 5 years warranty against defective materials and workmanship.
The hemisphere structure is covered by a 2 year warranty
For frequent measurement chain verification a reference sound source will be required. G.R.A.S. supplies 114 dB types for the standard microphone sets and a special 94 dB adapter for the low-noise sets.
Depending on the use and your internal quality control requirements we recommend that the sets are re-calibrated at least every second year.
|Frequency range (±2 dB)||Hz||3.15 to 20 k|
|Frequency range (±3 dB)||Hz||3.15 to 20 k|
|Dynamic range lower limit with G.R.A.S. preamplifier||dB(A)||17|
|Dynamic range upper limit with G.R.A.S. preamplifier @ +28 V / ±14 V power supply||dB||146|
|Set sensitivity @ 250 Hz (±2 dB)||mV/Pa||50|
G.R.A.S. 67HA 1m CCP Hemisphere kit
The kit comes in three configurations for respectively 4, 10 and 20 channels.
Reference sound sources
|G.R.A.S. 42AB||Sound Level Calibrator (114 dB)|
|G.R.A.S. 42AP||Intelligent Pistonphone (114 dB)|
|G.R.A.S. RA0090||Pistonphone Coupler for G.R.A.S. 42AP|
|G.R.A.S. AA0037||For CCP Microphone sets: 10 m BNC-BNC cable|
|G.R.A.S. AA0009||For LEMO Microphone sets: 10 m LEMO-LEMO cable|