Walls & Ceiling-Diffusion or Absorbtion?

Hi, What would you guys recommend for: control room 9ft x 13 ft (8 ft celing)(floor will be carpet)? live room 13ft x 17ft (9 ft ceiling) (floor will be vinyl)? im looking to 'tune' the rooms. Thanks!

blackdrum wrote:

Hi, What would you guys recommend for: control room 9ft x 13 ft (8 ft celing)(floor will be carpet)?

No Carpet on the floor. I'd Do the Control room in this design http://www.saecollege.de/reference_mate ... ge%202.gif What is your floorplan? Do a quick mockup I think I responded on your other thread "vertigo" This link above is from the SAE sight. Finally, the design of these room is "tuned" for lack of a good way to say it. Bryan Giles

Thanks for the reponse! Should I rip up the carpet in the control room? (its the thin cheapo industrial blue stuff.) Other people have suggested not to go w/ slot resonators in the control room because it is so small. Do you think i should build them or just use fiberglass insulation? another person suggested to just go around the room with a mirror, and place fiberglass or foam panels wherever i could see my tweeters in the mirror. Ever hear of this method? Thanks Again!

I would build them, the help minmize/control flutter echo in the room, All Fiberglass does is absorb, will not stop flutter echo. Johns wall mounted one are nice, and take up very l;ittle space. Like I said elsewhaer, My Room was 10x13, and with everything built doesnot feel to small to me. The Mirror thing is interesting, but I have built a room to Johns specs and it works. trust what works. Bryan Giles

Actually, the mirror trick would also work in John's designs - the point of the mirror trick is to identify early reflection paths, that is, sound paths to your ears (other than direct ones) that are less than about 22 feet longer than the direct path to your ears from your speakers. The reason the mirror trick would work in John's designs, is that RFZ, or Reflection Free Zone, is all about re-directing early reflections AWAY from the listener until they've had at LEAST 20-25 milliseconds of delay; this is accomplished by the splayed walls and sloped upper front wall/ceiling design. In rooms that are small enough NOT to have a minimum ROUND TRIP path from mix position to rear wall of at least 22-25 feet, it's not recommended to use diffusion on rear walls but use absorption instead. Building slots for front of room is fine, as long as they are splayed enough to redirect sound away from the mix position. Their advantage, besides trapping specific frequency ranges that could cause problems, is that they don't totally deaden a room which may already have too much absorption, depending on what OTHER treatment has been done... Steve

Bryan, > All Fiberglass does is absorb, will not stop flutter echo. < Say what? In a room that small and without angled walls, fiberglass is the only viable way to stop flutter echoes. --Ethan

this is good stuff....keep going! so on the back wall, do i want foam or fiberglass or what? what about the floor? i hear some say rug is ok for control room, some say its not? whats the deal? we are also ready to install the glass window. we found someone who will put in a window in each wall (2) for $250USD. anything i should know befor we go ahead? thanks!

Really Ethan. Hmmm So just putting an absorptive material on parallell walls will stop flutter echo? Aww man you have ruined everything I have learned over the past 7 years. Back to school I guess. All absorption does is reduce, it does not eliminate. Man You and barefoot burned up a few threads debating this about 4 months ago. You need the angles regardless blackdrum, that is specifically why I believe John came up with his portable DIY designs that take only about 4 to 8" from either side of your room to implement. Maybe I have been mixing in too many bad rooms that had treatment placed on parallel walls and Now I got it good I want others to enjoy what I have. Oh Well, so much for wanting the best for others.... LOL Anyway...... SO I have to disagree with you again Ethan. Bryan Giles BD, if you do JUST fibreglass you will find down the line that your mids just ain't accurate enough. Enjoy the weekend Fellas....

Drums, > so on the back wall, do i want foam or fiberglass or what? < In a control room that small you want absorption in the rear. Foam works, but fiberglass is better, cheaper, and fireproof. Though fiberglass is more hassle because you have to cover it, and it's less pleasant to handle. For either material, the thicker it is, the lower in frequency it absorbs to. This is the real issue. Foam that's only half an inch thick will still absorb 100 percent above 1 or 2 KHz. As the material is made thicker, and optionally spaced away from the surface it's mounted to, the absorption extends to lower frequencies. > what about the floor? < It depends on what's on the ceiling. For small rooms I prefer an absorbent ceiling and a reflective floor. Expensive wood tiles are good, but so is cheap linoleum and even bare or painted cement. So what's best depends on your budget and how much you enjoy doing grunt labor and construction. :D --Ethan

Bryan, > you have ruined everything I have learned over the past 7 years. < I'm so sorry! :D > You need the angles regardless blackdrum < I'm sure that's the ideal solution. Whether he will do that remains to be seen. If not, what do you recommend other than fiberglass? :twisted: --Ethan

Well Ethan, when you got me you got me. :D If he doesn't take the advice we give then what. LOL But I think he will. Bryan Giles

You know I thought of an answer. He could always move to the country, clear out a nice wide area and mix outside. :D Man this is gonna be a good weekend. I am having too much fun laughing all over the place. Bryan Giles

HI, thanks for all the responses. the ceiling is drywall (gypsum)....what should i do about that? also, we have a lot of leftover rockwool. could i use that in place of the fiberglass? thanks again! Blackdrum

Yes you can use the rockwool in place of the fibreglass inside your resonators, etc.. But for surface mounted uses, depending on your brand of rockwool, I'd use the fibreglass as it is more rigid and stays together better. The Roxul Wool I use is not as sturdy as say OC-703 Even though it is as dense 4pcf. Note: I managed to get my hands on some old OC- Mineral wool and it was much more sturdier than the Roxul I was using though they were evenly effective. Bryan Giles

Bryan, > when you got me you got me. :D < I'm not trying to "get" anyone, just keep things practical and on-topic. :) > He could always move to the country < I've been arguing for a few weeks with some guys over in rec.audio.tech about the suitability of using DSP to solve room acoustics problems. These folks keep insisting that DSP alone can solve every possible room problem, so there's no need for acoustic treatment. What they overlook completely is the practicality of that approach. Yes, DSP can fix everything, but only for an area of one square inch! My wife would just love that. "Honey, if only you were sitting here, instead of next to me, you'd just love the way this movie sounds!" --Ethan

Just having fun Ethan. :) Yeah everyone wants an easy fix to lifes physic problems. :)

ok. great info! thanks! so here's what Ive decided for the control room: -john's slot resonators for sides & front of room (do i "splay" the front room resonator to face up to the ceiling? or off to the sides?) -OC Fiberglass Insulation on the back wall (do i make a frame out of 1x1s? wrap in burlap?) -Vinyl floor. (all i can afford, will this be ok? better than carpet?) -Absorbtion on the celing (cover it all? or just in certain places?) Im not going to 'tune' the 'LIVE' room until i finish the control room. Im getting burned out quickly. This seemed like a great & exciting idea, but its A LOT of work!! :)

The fiberglas can be wrapped in cloth (fireproof, preferably) which can be glued to the outer perimeter in back, like wrapping only the visible portion of a christmas present and gluing the paper on the rear edge. If you want, you can make the panels portable by mounting them like this http://johnlsayers.com/phpBB2/viewtopic ... ight=mount Vinyl floor is fine, carpet sucks. (literally, for high frequencies) - you generally want more EVEN absorption, in order to keep the room neutral sounding. Cover the entire ceiling if you can - minimum over the mix position. See drawing. Hope that helped... Steve

hi we went way over budget, so i was wondering if it would be ok to leave just painted plywood for the floor in the 'live' room (studio) instead of putting down tile??? also, in the SAE diagram which was recommended to me here: http://www.saecollege.de/reference_mate ... ge%202.gif i am a little confused as to which panels are which. can anyone tell me where i need john's slot panels and where i need other panels? thanks PS-the final dimensions of the rooms are: control room = 8ft 4 inches X 13ft 10 inches (7ft 11 inches ceiling) 'live' room (studio) = 18ft 6 inches X 8ft 11inches (8ft 8inches ceiling) (on floating floor) a little different than I said in the earlier post. :)

Acoustically, the plywood won't be a problem. However, in order to get paint that is durable enough for floor use you may end up spending as much as it would cost for sheet vinyl, which would last a lot longer than paint. "can anyone tell me where i need john's slot panels and where i need other panels? " Not sure which ones you're unclear on - they all seem to be labeled as near as I can tell... Steve

the ones i am unclear on are the ones in the back of the control room labelled "Cloth Front" Thanks!

Guess that part is a little vague if you're not familiar with all of John's sites - go here - http://www.johnlsayers.com/HR/index1.htm and scroll down to "THE REAR WALL ABSORBER" - If you build to the floor plan you posted, you would just enlarge the dimensions of the absorbers and build the V-shaped part as two absorbers... Steve

I have two questions regarding diffusion: 1. Knightfly, you said "In rooms that are small enough NOT to have a minimum ROUND TRIP path from mix position to rear wall of at least 22-25 feet, it's not recommended to use diffusion on rear walls but use absorption instead." My room will be right on that cusp, measuring about 22 feet from mix to wall to mix. Would it be a good idea to have some diffusion and some absorption, or should I go only with absorption? 2. Of all the differing types of diffusion, I'm finding it hard to determine which type would be best. I've read posts in this forum that say that radiused wall sections aren't really diffusion, but this product: http://www.soundcontrolroom.com/saturn.htm claims to be a diffusor, and uses radiuses to accomplish it. Other than Helmholtz types, which I can understand being more useful in the low frequencies, can anyone tell me the practical difference between the Skyline, Saturn, Well, and Radius types? In other words, if I'm picking out diffusors, how do I know which type to use? Thank you very much for your time! -Craig

1. At that distance, it would be borderline. I would play it safe and build the back wall absorptive, then if you wanted to "play around", try a DIY diffusor or two and see if it makes things better or worse. 2. "radiused wall sections aren't really diffusion" - Alton Everest would disagree with that, as would I. If you send a sound wave into a convex surface, only a minute portion of it will come back the same direction. Granted, that's not RANDOM diffusion, partly because you can easily predict mathmatically where the rays will reflect to, but they're so scattered that it would be difficult to tell the difference once you're 10 feet from the diffusor. A Helmholz is an absorber, not a diffusor - although, the slots might cause a tiny bit of diffusion. The Saturn and Radius types (Polycylindrical) could be similar if you were to mount some small radius poly's 90 degrees to others, so the diffusion was hemispeherical. However, $50 apiece makes me reach for my power tools... The skyline and QRD types do similar things, but again in order to get hemispherical (both axis) diffusion, you need to mount some of the QRD types in opposite axes (some vertical, some horizontal) - From a DIY standpoint, the QRD's would be easier to make (assuming you actually follow the formulae instead of just gluing random blocks to a sheet of plywood and painting/staining it) In this type as well, I see the prices they want for a $3 piece of injection molded plastic and immediately quit thinking about it in non-DIY terms. Before I spent much time and effort on building anything, I'd put some large bookshelves at the rear of the room and randomly fill them with books, bric-a-brac, etc, anything that doesn't RATTLE, and see if you like the effect. The real deal will do more, but it should give you an idea whether it's worth pursuing... Steve

Steve- Thank you so much for your response. I agree about the price of molded plastic. I also agree about the radius diffusion - it has struck me in exactly the same way. That maybe it's not true diffusion, but in the practical application, it'll be exactly the same thing. I'll use absorption for the rear wall, and save the radiuses for the live room. -Craig