Control Room design question.

Hi everyone, I am a newbie poster to this forum so please excuse any mistakes in etiquette. I am very impressed with the level of expertise displayed here, thank you in advance for any help that you might be able to offer. Please let me know if this is the wrong space for this post or if my questions have been answered somewhere else, I'm sure they have. My plan. I'm located in Washington State, near Seattle. I have a big open warehouse space available in a quiet setting - 45 feet long by 32 feet wide by 20 high ceilings. It is currently used as a performance space with a little stage at one end. It has one office in the back right corner - 12' L x 10' W x 8' ceilings. I would like to install a control room in the main space plus, using the office, a separate vocal booth and workshop/gtr cabinet room. I have drawn up a plan and am wondering if you all might take a look and offer any suggestions. Current plan. Control Room inside dimensions- 19 feet long x 14 feet wide x 10 foot ceilings. trying to start with the golden rule ratio thing 1:1.4:1.9 I plan on a exterior 2x6 steel stud wall 24" on center with 2 x 3" batts of Roxul AFB inside then a 2" air gap then a 2x4 wood stud 24" on center with 3" Roxul AFB inside. Ceilings will be 2x8 joists with 3"x2 AFB x2. The room's width shape will be narrower at front (12 feet) splaying out to 16.5 feet and then coming back to 12 feet in back. The splay angle is around 10 degrees each side. The ceiling height will be lower at front wall 9 feet and slowly rising to 11 feet. Thinking that the average width will be 14' and average height will be 10'. My main question aside from does this look reasonable is what is the recommended material (rock) to use on the 2 inside faces of the walls. (next to the 2" air gap) RC8 (resilient channel mounted ) + 5/8 rock or RC8 + 1/2" rock or RC8 + 1/2 " soundboard or 5/8 rock with no RC8 or Open faced ( no rock or covering ) don't think this is the answer but I'm not certain For the rest of the wall surfaces: I have heard of suppress 1" claiming to be the best ( as good as 5 sheets of sheet rock) for the outside wall, but at 125$ per 4x8' sheet it seems excessive. 5/8 suppress is slightly easier to swallow at 65$ per sheet. http://www.supressproducts.com/products/index.htm So currently my idea for the wall construction is (from outside Control Room in) 5/8 suppress rock -> RC 8 Resilient Channel -> 1/8" Foam pad -> 2x 6 steel stud -> ??? (RC8 + 5/8 rock but not sure) -> 2 " air gap -> ??? (RC8 + 1/2 rock- but not sure)-> 2x 4 wood stud -> 1/8" Foam pad -> RC-8 -> 5/8 rock and 1/2 rock glued together (with auralex sheet block in between maybe? ) Here's the plan as I have it. Dimensions should be pretty close to accurate. Speaker placement and Board are very rough. I'm hoping to be a live drum/band tracking room as well as the option to do multi-media i.e. commercial voice over/ film scoring - ready for anything. Thank you very much!

Hi "bren3303", and welcome! :)

Please let me know if this is the wrong space for this post

Right place! No problem.

I have a big open warehouse space available in a quiet setting - 45 feet long by 32 feet wide by 20 high ceilings.

:shock: :mrgreen: Lucky you! Most home studio builders would kill for a place like that! Envy, envy....

Control Room inside dimensions- 19 feet long x 14 feet wide x 10 foot ceilings. trying to start with the golden rule ratio thing 1:1.4:1.9

OK; several points here. First, there's no such thing as a "golden rule ratio". That's a myth that carries over from some home theater and audiophile forums, from well-meaning folks who unfortunately don't really understand what they are talking about. Rather, there are good ratios and bad ratios. There are a number of known good ratios, that have been calculated and tested by scientists with names like Bolt, Louden, and Sepmeyer. In fact, the ratio " 1 : 1.4 : 1.9 " is Louden's best ratio, but comes in at number 5 on the list of really good ratios. so there are better ones. There's nothing wrong with it, of course, but it sure is good to know that you have alternatives. You might want to try out some of those. Next, ratios only apply to rectangular rooms, with six parallel walls (4 plus floor and ceiling): yours is not rectangular, has eight walls, and none of them are parallel! So room ratio calculations don't apply to such a room. At least, not accurately: They can still give you a rough idea, but you have to use the average vale the, not the biggest or smallest (average width, average height, average length). In your case, it sounds like the dimensions would be 18.5, 13.5, 10, so the ratio is more like 1 : 1.35 : 1.85. But even so, you have eight walls, not six, so even that isn't valid. Which leads to the next question: Why are you cutting off the rear corners of your room? :shock: that's a huge wast of very important space. Exactly where you should have your rear bass traps, you cut off the only place where you can put them. Those diagonal "slices" serve no useful purpose. I keep seeing that shape, and I'm not sure where it is coming from, but it really doesn't make a lot of sense as the shape for the inner leaf. It makes sense as the final shape of the room, WITH TREATMENT, but not for the inner leaf. Treatment does not count when figuring room ratios, since it is the hard, solid, rigid boundary of the room that matters. And finally on this point: Why are you splaying the front walls of the control room? There are several good, valid reasons why you might want to do that, but it helps to know what your reason is, to check if you are doing it correctly. Different reasons require different angles...

I plan on a exterior 2x6 steel stud wall 24" on center with 2 x 3" batts of Roxul AFB inside then a 2" air gap then a 2x4 wood stud 24" on center with 3" Roxul AFB inside.

Just to clarify 8and this is a common misunderstanding): That's not a 2" air gap: That's 9" air gap. There's a 2" space between the frames, yes, but the air gap is 9". 3-1/2" from the studs on each side, plus the 2" between the stud walls. Acoustically, insulation is still mostly "air". so when you do your MSM calculations, make sure that you use 9" as the size of your air gap, not 2".

My main question aside from does this look reasonable is what is the recommended material (rock) to use on the 2 inside faces of the walls. (next to the 2" air gap)

Whoa!!! Maybe I misunderstood you: Your walls should look like this: The drywall goes on the OUTSIDE of the studs, not the INSIDE! So there is no drywall "next to the 2" air gap". If you build it like you say, it would look like this: ... which would give you pretty lousy isolation, due to the tiny air gap. And it also brings up the question: Why would you want to have bare insulation and studs facing the wind, rain, sun and snow? :shock: There seems to be something wrong with what you are planning here, or maybe I just didn't understand what you are saying....

My main question aside from does this look reasonable is what is the recommended material (rock) to use

Plain old fire-rated 5/8" drywall. Or if it happens to be cheaper where you live, then you could substitute 5/8" OSB, plywood or MDF. What matters, acoustically, is mass. That's what the sound waves "see" and react to. The greater the mass, the more isolation you get, provided that the rest of the wall is built correctly. A studio wall is a tuned system, and there are only two variables in the equation for calculating MSM resonance: the mass on each of the two leaves (in other words, how heavy the drywall is), and the size of the air gap between them. If you increase the mass, or increase the size of the gap, then you improve the isolation. But if you increase the mass and decrease the gap, you get worse isolation. The absolute MINIMUM air gap that you ever want, is 4". Below that, the amount of mass you need to compensate for the reduced space gets to be quite impressive, and actually takes up more space than you save by making the gap thinner...

RC8 (resilient channel mounted )

Ummmm... why do you need resilient channel? Your leaves are already decoupled (you did say you plan to have two stud frames, one for the outer leaf, one for the inner leaf), so decoupling again is pointless. Decoupled is decoupled. You do not need RC if you are building double-stud walls.

+ 5/8 rock or RC8 + 1/2" rock

Forget that: another myth from the world of home theaters. Yes, it is true that there is a slight benefit from having two different thicknesses of drywall on a leaf, due to the different resonant frequencies, impedance changes, broader Q of the coincidence dip, etc. But in fact the "benefit" does not compensate for the reduced mass, thinner wall, and lighter, more flexible second layer. In reality. two layers of 5/8" drywall outperforms one 5/8 plus one 1/2. So forget the myths, and do yourself a favor: If you need high levels of isolation "which you seem to, based on what you are doing), then just go with two layers of 5/8" fire-rated drywall on each of the two leaves (total of 4 layers).

I have heard of suppress 1" claiming to be the best ( as good as 5 sheets of sheet rock) for the outside wall,

:shock: I'd take those claims with a very large pinch of salt! There are no magical materials that somehow bypass the laws of physics. Sound waves are stopped by mass, plain and simple. Sound waves do not care how much you pay for your mass /they can't read the price tags!). All they do is react to the amount of mass in front of them, and they follow the laws of physics every single time. Mass law says this: TL = 20 log (Ms x f) – 34 dB where: Ms = Surface Mass (lb/ft2) and F = Frequency. Do you see any place in that equation for price tags, or magical incantations? :) Mass law is the most basic, best tested, and very well understood equation of acoustic isolation. It works, and no matter how hard the marketing department of a company works, or how many wonderful words they put in their press releases, Mass Law does not change. So if you see a product claiming to give you over 75 dB of isolation when it isn't even decoupled, well, I'd look at that with a really, really skeptical eye. In some of the best, most complete laboratory tests ever done on soundproofing (IR-761), in nearly 400 pages of testing, NOTHING got an STC rating greater than 70. The very, very best was STC-69, obtained from a very well decoupled MSM wall, with double studs, 2x4 24OC, 2 layers of 16mm Type X drywall on each side (total 4 layers), 3-1/2" of fiberglass insulation on each side, and a one inch gap between frames. So I find it rather hard to swallow a claim that a fully coupled wall with only one layer of magical mass on each side can be six times better at stopping sound. I'd really like to see a report from an independent acoustic lab that shows the product actually does perform like that. And besides, STC is a pretty useless way of measuring sound isolation in studios anyway. TL graphs is what counts. Strange that they don't publish any TL graphs on their web site, or indeed, and tehcnical data at all! Marketing hype might be wonderful, but in reality this is just pure wishful thiniking: "Only Supress has STC 50 performance in a 1/2” thick panel". A single panel, all by itself? 1/2" thick? STC FIFTY??? Ummm... no. Sorry. I don't think so. That would defy mass law. They say that this magical 1/2" panel weighs 2.08 lbs/ft2. Plug that into the equation for mass law (above), and see what you get... At 1 kHz (center of the spectrum), it works out to 32 dB. And at frequency that is useful for studios, 80 Hz, it works out to 13 dB. Oops.

but at 125$ per 4x8' sheet it seems excessive.

Ummm. Yup! I guess marketing must be expensive! OK, sorry for the rant! But I do get a little upset when I see products that apparently come from a different universe, where the laws of physics don't apply...

5/8 rock and 1/2 rock glued together

Bad, bad idea. Gluing together two sheets of drywall makes things worse, not better. The sheets are no longer free to slide over each other, so there is no damping of bending waves from friction. Green glue would help a lot, but green glue is not glue: it is a constrained layer damping product. So no, don't glue.

Speaker placement and Board are very rough.

Yes, and you should fix that: it's not easy to evaluate a room that doesn't show things accurately! :) So try to correct that: move the mix position away form the middle of the room, to the correct location, fix the speaker angles to match the EBU 5.1 specs, fix the "chopped-off" corners are replace them with bass traps, then post the updated drawing. I'd also suggest that you might want to do this design in SkethUp, which makes things a lot easier for you, and for us. Line drawings are only 2D, but sound is 3D, and line drawings don't show the level of detail of the materials that would help us understand your plans. SketchUp is free, and very powerful (once you get past the learning curve), and it sort of is the "standard" on the forum. Anyway, you seem to have a really good space for building your studio, and a good basic plan. It just needs cleaning up a little, and the details sorting out, then it can be pretty darn good, I reckon. - Stuart -

Hi Stuart, Thank you so much for your reply. I am really grateful. I will work on the sketchup, make the adjustments to the room angles, sheet rock sizes etc. and post very soon. Have a wonderful weekend. Brendan aka "bren3303"