Glad it was helpful!

We asked John and this is his reply: You want a balance of absorption and reflection and of course diffusion to obtain balance. Some rooms like blackbird studio c use a lot and northward acoustics uses very little. Bass traps on the back wall are far more critical than diffusion. Some combination of bass traps and diffusion. But it is within context overall. And depend how far away that wall is from the mix position.

I will check with John Dykstra and get back to you.

@@RecordingMag Thank you. It's unfortunate that nobody has at least setup 3 dolly's on tracks, one for a diffuser, one for a speaker pointed at the diffuser, and one for a binaural mic behind the monitor pointed at the speaker/diffuser, tests done at different distance increments. It's too bad nobody has done this, perhaps because the expense is high and there isn't much business incentive since general diffuser dealers don't exist hahah, but maybe Sweetwater will one day...

@Don P And what are you? You think the term bass trap is a proper terminology or a marketing term? Pick one if you can...

@Don P No. Sorry. I don't currently work for anyone. Please don't make up fiction. Yes, I have met Dennis a long time ago, and I've learned a lot from him and I have been in a room treated with his products. And yes I do prefer his products than others because I have personally used many different products and materials throughout my life with less than desirable results. Yes, I have talked to other acoustic engineers over the years, so I'm coming from that perspective. Yes, I used to think of low frequency absorption as "bass traps", but I have been told by SEVERAL acoustic engineers that that is a MARKETING term and it's commonly used by people that use it for simplicity purposes, but most of them really didn't understand low frequency absorption either.

@Don P drblank was taken by someone else and I chose this screen name.. But Dennis isn't drblank either. Seriously, please try to learn something rather than putting out nonsense..

@Don P Question. Have you heard Acoustic Fields' rooms that they have built or treated with their products? If you haven't, then I highly suggest you do. To me, it was the best sounding room I've ever been in. And yes, I've been in top end studios, home studios, high end 2 channel and home theater rooms, plus I've had a variety of products and materials in my own rooms. So If you have the chance, check em out. You might change your mind. Yes, there products aren't cheap, but they aren't trying to be the low cost leader. They want to make products that perform well, well built and outperform competing products and doing so without gimmick products. I'm not mentioning names, but there's a lot of gimmick products on the market that aren't that great. They might look cool, but they don't really perform as well as another product..

@Don P Here's the issue, when you have to absorb low frequencies in the 50hz and below range, it requires a lot of mass. If you understood low frequency energy, you would understand this. BTW, other companies make low frequency absorption products that are actually more expensive, but don't do as well. Now if cost is an issue, then buy the DIY yourself plans, make your own cabinets and buy the activated carbon from them so you essentially save a lot of money. OR, you won't be able to manage that low frequency energy nearly as well. You get what you pay for Don. If you want to build your own walls, they also design the wall structure so the low frequency absorption is inside the wall cavity. You can either have them do it, or if you have carpentry experience and a table saw, you can do it yourself. They do have many customers that buy the DIY plans and DIY. Why do you think they have customers that buy and use their products over their competitors? They do have lots of customers that bought something else, weren't happy with it, and then switched over. Remember, with any type of low frequency absorption, you need a deep cabinet that resonates at the desired frequency, there isn't any option. Then it's a matter of how much mass and how good the fill material is with absorbing that energy. Having talked with Dennis, he's built the same cabinets using every fill material commonly used and he stumbled across Activated Carbon purely by accident. But if you did some research, a speaker mfg. actually has a Patent for using activated carbon inside the speaker cabinet, KEF is the company that has that patent. There was also a University Study in the UK that tested Activated Carbon and they measured it to be effective down to even 20hz. That's because of the porosity of activated carbon and that it's a much more dense material than other materials commonly used. It's physics. Now, if you don't NEED absorption down to 30hz to 50hz, then you don't need it. but if you have full range speakers and/or full range instruments in a studio, and your room is relatively small, then you are going to have that problem. Small rooms have troubles in the low frequency range and you either use the right products, and placement or you'll never get the room to sound right. Remember, how low are the 2 lowest octaves on a piano? 110hz and below. How about a 4 string bass guitar? The low E is 41hz. How about a kick drum? Around 50hz. How about an upright bass? They can do even lower than 41hz. Much of today's music that's hybrid (acoustic and synthesized sounds) have all kinds of things down in that low end. Low frequency energy is simply VERY, VERY expensive to manage. PERIOD. Otherwise you're using a piece of toilet paper against a tidal wave and it's simply not going to work. But it all depends on how much energy you are putting in the room and what your room dimensions are.. Most other products aren't really treating those low frequencies, they are treating higher frequencies or the harmonics of those lower notes and that doesn't produce the best sound. Seriously, check their rooms out. Again, you can buy their DIY plans for $50 and build your own cabinets. heck, just build two using their activated carbon and see for yourself how well just two units does. Depending on your room, you might need more than that. Yes, there are test data on their products. You just haven't looked hard enough. I've seen the actual test data from RAL. Here's test data link to their ACDA 12 cabinet. www.acousticfields.com/wp-content/uploads/2012/01/ACDA-12.pdf It's right there on their site. No, they can't get the data for 30hz as no one can "certify" down that low, however, RAL did show on another test data that Acoustic Fields did have that did go down to 30hz and it was exactly what he says on their website.. Here's an article from the University from UK that measured activated carbon and they claim that it was effective down to 20hz. usir.salford.ac.uk/id/eprint/23061/1/JASMAN1321239_1.pdf So, please review the links and don't make false claims. think of this way, if you were able to get anything from GIK that could be as effective in that low end range, you'd have to buy a bunch of them and the cost differential wouldn't be that much different. Remember, you NEED a deep cabinet, you need lots of mass (which is heavy and expensive) and you simply can't absorb 50hz and below that well unless you have the depth and mass to do it. It's like building a wall to prevent 30hz from leaking in/out. You can't do it with thin walls with building insulation, that simply doesn't work. You need lots of mass. I find GIK to be products that are cheap for a reason. I've compared absorption coefficient curves of several of their products. You get what you pay for Don. I can't help if you don't have or don't want to spend the money. But don't put something else down because you can't afford it. They are obviously doing something right since they do get GIK customers that replace their products with their own and the customer is happier as a result. I have never heard of someone doing it the other way around. Again go visit a room with their products first. You may very well change your mind. And no, I know their products are expensive, but they do work and I've not heard anything that did as well..