Hi there "diedushka", and Welcome to the forum!
I really don't like talking badly about companies and people that offer acoustic products, but I do have to agree with your assessment! (I have to be very careful with what I say here, but I'm firmly in your corner...
)
What I can say about activated carbon is that is has great abilities to absorb smells, stink, and pollution, and is used in many filter products for exactly that purpose (
https://science.howstuffworks.com/envir ... ion209.htm ): to filter out the bad stuff, and only leave good clean stuff on the other side. Perhaps that website could use some activated carbon on the claims t makes...
It might help to filter out the garbage on only let through the good stuff. Of course, it's debatable how much "good stuff" would get through... It might be a lot, or it might be nothing at all!
That's the issue here.
I've tried researching but there isnt much info about the company or the guy
Exactly!
You are on the right track.
All i could find was one old thread on Gearslutz that basically went completely bonkers and got locked.
Yep! I have not read that thread myself, but I can imagine that the folks over on Gearslutz who really do understand acoustics, would have expressed their skeptical opinions about the claims. There's some good guys over there, and it's hard to hype snake-oil and magical pixie dust acoustics with them. They will certainly express their opinion on unfounded claims, quite accurately...
but i was thinking if some of the veterans here can chip into the activated carbon 'technology'.
Have you tried googling it? There actually is some valid research that shows activated carbon can absorb low frequency sound, in laboratory tests. But there's very little research about how that translates to the
real world. There's some pretty wild claims out there (as you saw) with precious little actual testing in recognized, reputable acoustic testing laboratories. Maybe it does work: Maybe it doesn't. But until there is validated independent research results that show substantial advantages, I'm not going to bother using it in any of my designs.
On the other hand, any "acoustic" web site that shows graphs where the coefficient of absorption is shown in percentage, raises some very large red flags in my mind, and leads me to wonder about just how good the acoustic knowledge is! For the record, the coefficient of absorption of any materials does NOT show what percentage of sound it absorbs! Not even close. If that were the case, then there are many products out there that could rightfully claim to absorb more sound than 100% of the sound. There really are products that validly show absorption coefficients of 1.2, which would have to work out to 120% if you trust a graph that shows coefficients as percentages.... That's absurd: it implies that if you pump 100 watts of sound energy into the material, it would absorb 120 watts! In other words, it would absorb MORE energy than you gave it! It would make the room MORE than silent. It would become "negatively silent"
That's like saying a color is blacker than black, or that water is wetter than wet... it is physically impossible. Anyone who uses a graph where the coefficient of absorption is show as a percentage, instead of coefficient, is either highly ignorant of acoustics, does not understand what the test actually shows, or really does understand but is deliberately attempting to mislead. Draw your own conclusions....
For example, here are the results for a validly done acoustic test of the very common OC-703 insulation, from Owens Corning:
oc-703-coefficient-graph.jpg
According to that, it correctly shows that the coefficient of absorption is greater than one at some frequencies. It is 1.24 at 500 Hz, and 1.15 at 4 kHz. Very true. Very correct. But that does NOT mean that this product absorbs 124% of the sound at 500 Hz! It just means that the coefficient of absorption is 1.24! That's all.
Here's a graph taken directly form the website you mentioned:
wrong-coefficients-graph.jpg
Notice the vertical axis? "Percentage absorption"? Really? Seriously? Ummm.....
For the specific product shown in that graph, they claim they really did get it tested in a reputable lab. But here's the ACTUAL test results released by that lab:
wrong-coefficients-graph-correct-version.jpg
(At least, I THINK that's the same product! I did click on the link in the product description that says "acoustic labs test results" [
https://www.acousticfields.com//wp-cont ... CDA-10.pdf ], but the graphs don't seem to match, so maybe it's for a different product?). But as you can clearly see, when the results are presented correctly, with correct scaling, they don't look so interesting... and the acoustic lab correctly labeled the vertical axis as "absorption coefficient", without any percentage signs!
Curiously, I'm wondering why anyone would even show such a graph when trying to sell a product! An absorber that has such a very low coefficient of absorption seems pretty useless, to me.... An absorber that only absorbs 0.1? Huh? Compare that to the graph above for OC-703: it absorbs WAAAAAY better, only costs a few dollars. So why would anyone use such a graph to try to sell an absorber that clearly doesn't absorb? Hmmm.....
On the other hand, the actual lab test report identifies this device as a "low frequency diffuser", in which case I'm wondering why someone would .bother testing a DIFFUSER to see how well it ABSORBS! ?
That's like testing the color of your car to see what it tastes like....
So that's rather curious....
There's also the issue of cost: If I can build a really effective bass trap in a control room, such as in this one (currently under construction)
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=21368 for a couple of hundred dollars, why would I want something that costs a couple of
thousand dollars? Is it ten times better, to justify the ten times higher price tag? You be the judge....
The website also doesnt provide any patent or similat technical data in relation to acoustic effectiveness other than some basic drawings that any beginner engineer can logically draw
Correct! Indeed!
I would expect that a sophisticated high-priced device would come with extensive technical test reports from independent, reputable, recognized acoustic test labs. I wonder why they don't provide that for most of their products? Did they get their devices tested? If so, why do they not show the results? And if they did NOT get it tested, why not?
The videos themselves are also just a bunch of abstract blabberings about acoustic priciples
I can't argue with that...
And while it got my interest in the beginning - the more videos I watched, the more the guy looked like a fraud. Or maybe just a cheeky marketer, who tries to sell his products to uneducated musicians.
It's probably better that I don't make any comment about that statement...
Maybe there are people who actually used his products in their studio and made measurements? WHo have some experience or can basically explain the whole activated carbon principle and why and where it would be more viable then say a Helmholz or panel?
I have no personal experience with that device, nor do I plan to. Rather, I prefer to stick with using only tested, proven, effective devices in my studio designs. When using those devices (typical devices such as the ones you mention, that can be built easily and inexpensively, or purchased from reputable acoustic suppliers such as Real Traps, GIK acoustics, and others), it is entirely possible to get spectacular results, such as in this studio:
http://www.johnlsayers.com/phpBB2/viewt ... =2&t=20471 There's no "magical" materials or techniques used in there. Only standard, proven devices, designed on the basis of known and well documented principles of acoustic treatment.
My question would be: if it is possible to get the results seen in places such as these using inexpensive treatment based on conventional and well-understood acoustic principles, then why would I be interested in using very expensive, extremely heavy products that might or might not achieve the same results, but with no way to verify it they actually work or not?
To be honest, if you are planning to treat your studio, don't bother with hyped-up questionable materials of products: just use normal tried and proven designs, based on simple, common building materials.
- Stuart -
