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question about theory behing the activated carbon pellet technology
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Acoustics Pro
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February 22, 2017 - 1:36 pm
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Hi Dennis and everyone! I have a question about the activated carbon pellet technology.
I have been reading the free eBooks (thank you Dennis!), and watching the youtube videos .

Dennis, when discussing the application of activated carbon in low frequency acoustic absorption ,
you mentioned each gram of the material has approximately 2400 square meters of surface area.
My question is - why is this surface area important?

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February 22, 2017 - 5:10 pm
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Hi Jason, I think the gram coverage might be overstated but nonetheless, carbon has a large absorption coefficient. I tried numerous combinations (12) of different thicknesses for the carbon filters but settled on the 3" thick filter to achieve the absorption curves I desired. For The ACDA -12, I wanted everything I could get from 30 - 50 Hz. I got 30 + % at 30 Hz. , 63% @ 40 Hz. and 100 % @ 50 Hz. This is a frequency response range that produces many issues in 97 % of the small rooms in my data base. Here are test results.

I also needed a broadband absorber from 30 - 200 Hz. This was also a frequency response range found to be problematic in 95 % of our rooms in data base. The average octave coefficient is around 23 % and it is quite linear. Here are the test results: https://acousticfields.comcont.....A-12.pdf/-

These are pressure activated devices. Front walls slow energy wave, middle cabinet space area of low pressure produces pressure variance, rear/ side wall/ rigidity forces front walls to vibrate in sympathy with pressure. The carbon filters are basically a perforated absorber filled with our carbon technology which we process ourselves. With our ACDA series you have a perforated absorber inside a diaphragmatic cabinet.

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February 23, 2017 - 10:43 am
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Excellent, thank you very much Dennis! I will be contacting you with a few other questions if I cant find the info on the site here.
Have a great day!

Jason

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February 23, 2017 - 6:03 pm
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If we do a DIY build, can we purchase off the shelf carbon pellets? I see there are options online. Is there a significant difference between your processed carbon and stuff that is in, say, fish tanks?

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