Bay Systems Ltd

Mini Acoustic Chamber - MAC

Why would you want a MAC or a New Big MAC? If the acoustic environment inside your workplace is too noisy for the measurement that you need to make then a MAC or a Big MAC can provide a noise refuge in which the test item can be placed. The level of attenuation that can be achieved is > 80 dB at high frequencies. A MAC can deliver the results you need for < 3% of the cost of a hemi-anechoic room. Alternatively if the testing you have to do generates very high sound pressure levels then by placing the test inside a MAC you will stop annoying your neighbours. MACs can be manufactured to meet a wide variety of applications and can be made to fit the space that you have available. The dimensions of a MAC will influence what you can reliably measure. Degree of isolation. A MAC designed for use at high frequencies f > 500 Hz will be light enough to reposition easily within your laboratory. To achieve good absorption/attenuation and provide a valid measurement at frequencies below 500 Hz will normally mean a Big MAC with all dimensions exceeding 1 metre and weighing more than 300 kg. Consequently the Big MAC requires careful handling when delivered to site and is not so easily moved as a MAC.
Typical MAC & Big MAC noise isolation characteristics The 1/3rd Octave levels record the difference in sound pressure level measured inside and outside the MAC. The external microphone was positioned 0.3 metres from and directly in front of the MAC’s door. This is the point where sound attenuation should be the weakest. At frequencies in excess of 2000 Hz the attenuation exceeds 60dB and it is at 50dB for frequencies between 400 and 16000 Hz. The RT60 decay time for frequencies > 300Hz is 0.012 seconds. Purple = Big MAC Red = MAC
	Big MAC performance measured November 2017 showing 54dB of attenuation at 1kHz
	MAC performance measured January 2018 showing 48dB of attenuation at 1kHz
A customer measured internal noise level of a Super Big MAC; located in a working laboratory with the normal level of background noise, people talking etc.
Sizes and Weights of the MAC family of Mini Acoustic Chambers MAC - Designed to fit on top of a standard desk. External dimensions: - Length 1200mm, Width 800mm, Height 800mm Internal dimensions:- Length 800mm, Width 600mm, Height 600mm Opening Main door length 400mm height 300mm Cable ports 2 each 25mm diameter Weight 120kg Big MAC - Designed to give extended low frequency capability External dimensions: - Length 1500mm, Width 1500mm, Height 1250mm Internal dimensions:- Length 1200mm, Width 1200mm, Height 1000mm Opening Main door length 500mm height 400mm Cable ports 2 each 25mm diameter Weight 200kg Super Big MAC - Designed to give 10dB additional attenuation External dimensions: - Length 1500mm, Width 1500mm, Height 1250mm Internal dimensions:- Length 1000mm, Width 1000mm, Height 800mm Opening Main door length 500mm height 400mm Cable ports 2 each 25mm diameter Weight 300kg Super Big MAC A/V - Designed to give 10dB additional attenuation with Anti Vibration Mounts External dimensions: - Length 1500mm, Width 1500mm, Height 1275mm Internal dimensions:- Length 1000mm, Width 1000mm, Height 800mm Opening Main door length 500mm height 400mm Cable ports 2 each 25mm diameter Weight 340kg