Eddie´s Studio Design

I´ve been a member of the forum for some time, I´m going to build a recording studio on the first floor of my house located in Lima, Peru. Sometime ago I hired a local acoustician company to design the studio, I thought it would be very positive to have the Acoustic Designer located in the same city as the studio, because they know the materials around and could help with the construction, recently I got the blueprints after waiting several months for them and they are useless, no MSM structures, the rooms are rectangular, the fiberglass used is too dense, no use of room ratios, no reverb time. They swear it´s going to work but it doesn´t make sense with all the theory I´ve read in books from Rod Gervais, Alton Everest, Phillip Newell and also some members of the forum told me the design is hopeless. Now I decided to redesign the studio myself as I can´t afford another Acoustic Designer. I live in a residential area in Lima, Peru. I don´t have too much noise from the street as the studio is in quiet area, I have one house to the right and a building to the left with half basement used as a garage. The studio is next to the wall of the building. I already made the outershell of the studio, the walls (25cm solid calcium silicate bricks), the ceilings (20cm polyestirene bricks in between a concrete slab of 30cm) and the floor (concrete slab decoupled from the wall with 5mm of a material named impactodan used for impact vibrations). How loud I am? In the control room I mixed at low levels (maybe 85-90db) and for the Live Room I want to be able to record a whole band at 2am reaching 110-115db. My budget right now is something between 12-15k, the priority right now is the live room I can manage to do the control room later if it´s more than that. The Studio: The control room dimensions are 5.7m x 5.25m x 3.7m (L,W,H) The live room dimensions are 8m x 7m x 3.7m (L,W,H) I am aiming for an STC of 76db or more (http://www.soundisolationsystem.com/pdf ... 2904-4.pdf) Wall/Ceiling: The wall assembly would be 10” (25cm) solid calcium silicate brick, 5” air gap and 5” of rockwoll (40kg/m3) and 2 layers of gypsum 5/8”. The ceiling assembly would be a 20 cm polyestirene bricks in between a 30cm concrete slab, one layer of sound barrier (http://sonoflex.com/fonac/wp-content/up ... S-3009.pdf) , 8” inches of air gap, 6” of rockwool (40kg/m3) and 2 layer of gypsum 5/8”. I think I got the design of the control room right, but I´m not sure about the Live Room, I splayed one of the walls about 8 degrees for flutter echoes, do I need to splay more walls? Are the the walls/ceiling assemblies good enough for my purposes or do I need more inches of air gap or rockwool, I think I have a little more space I can spare. Cheers Eddie

sorry to hear about your design. maybe you could post it here for comments? anyways, nothing wrong with rectangular rooms since they are easier to build and model. plus in the CR, the angled walls will be treatments necessary to get the room modes and response under control. in the live room, especially a decent size one, you can use a variety of treatments on the walls to eliminate the flutter echoes and actually make the room better through adjustable treatments etc. on your budget, i'd start with the rectangular rooms properly isolated and use rigid insulation absorbers to tame the room as much as possible. then build out the more complex treatments later. on the construction - you should just build the steel stud wall separate from the brick/block wall. this will eliminate the need for the RISC clips and just use RISC / WIC clips to steady the walls. if you can, skip the barrier and add another layer of drywall. how will the drywall ceiling be supported? suspended? edit: ok - i saw your previous posting - if you can support the inner ceiling as shown, use isolation mounts to suspend hat channel and 3x drywall layers skip the barrier mass as the drywall will be better. use pink insulation to lightly will that 8" space. save the rigid insulation for the absorbers...

Hi Gulfo The inside the walls should use the pink stuff instead of rigid rockwool or fiberglass? Should I use steel studs or wood studs which ones are better or are the same? At the ceiling I skipped the barrrier for another layer of 5/8" gypsum, all the gypsum is suspended with acoustic hangers through a hat channel. Also all the 8" air gap is filled with insulation (pink stuff). The walls are pretty much the same with steel or wood studs with RISC/WI clips.

Here are some of the original designs if you want to check them out. The design is more for an industrial space or something like that. I don´t think they will work for acoustic isolation.

yes, use the pink stuff (or equiv - about 12-18Kg/m3) for in the wall insulation and use the heavier rigid insulation (48-60Kg/m3) for the absorbers you'll need to build.

my read on the plans - it looks like they assumed a level of isolation was already existing and it looks like they were defining treatments for impact noise and overall acoustics rather than a full isolation plan plus integrated treatments. based on their web site, they seem to be a credible organization but their experience in actual recording studio construction seems light compared to their work in industrial and commercial spaces where isolation isn't the primary goal, more where noise and vibration abatement and acoustical treatments are needed. not knowing what levels they went to in terms of evaluation of existing isolation and noise testing, it's hard to say for sure. if the bridge isn't burnt, you might reach out to them and have a sit down discussion to go over what their assumptions were regarding isolation etc so you can fully understand their thinking. it may be that adding the inner leafs cause a third leaf condition and maybe they were already aware of that. imho they are on-the-ground there and you should have some warranty for the proper operation of their design and it seems like a waste to toss that money away if it can be avoided.

Hi again, Eddie. I'm not surprised it didn't work out with the other design: it didn't make much sense for a studio. Like Glenn said: it seems more apt for noise control in an industrial space, but not very useful for a studio. Anyway, looking at your new plan:

The wall assembly would be 10” (25cm) solid calcium silicate brick, 5” air gap and 5” of rockwoll (40kg/m3) and 2 layers of gypsum 5/8”.

That should get you some pretty good isolation. Don't forget to seal the brick wall before you start building the stud wall. I also agree with Glenn: forget the RSIC clips, and just build separate stud walls. You might want to consider importing some proper sway-braces, though, considering the earthquake issue. You say you are aiming for STC 76: That's a pretty high level of isolation, and although the wall might get you there, your weak spot will be doors, windows and HVAC: You are going to have to give some very serious attention to those areas if you want to get STC-76 overall. Also, I'm not sure if you are aware that STC is not a good way of measuring isolation for studios, since it does not take into account the low end of the audio spectrum, which is the hardest part to isolate, and is exactly where drums and bass guitars live (among other things). It is better to use something like TL. But anyway, for that level of isolation you are going to need thick heavy laminate glass for your windows, very massive double doors with multiple seals, and long HVAC ducts with multiple 90° turns and also in-line silencers.

The ceiling assembly would be a 20 cm polyestirene bricks in between a 30cm concrete slab...

Once again, make sure you seal that concrete surface above you before you start building the rest. You need airtight seals all around your existing outer-leaf, and also on your new inner-leaf.

one layer of sound barrier (http://sonoflex.com/fonac/wp-content/up ... S-3009.pdf)

Forget that: you don't need it. It is just ordinary MLV. IT works, yes, but it is nothing more than very expensive mass. Sound waves don't care how much you pay for the mass up there; they just see the mass. It would be much cheaper (and more effective) to put an extra layer of drywall on the ceiling.

8” inches of air gap, 6” of rockwool (40kg/m3) and 2 layer of gypsum 5/8”.

How are you going to support that ceiling? Two (or three) layers of 16mm drywall is going to way hundreds of kg, and it needs very good support. Earthquakes are nearly as bad where you live as they are where I live, so you should think about using some pretty serious joists up there to support it.

The control room dimensions are 5.7m x 5.25m x 3.7m (L,W,H)

That's not a very good ratio! The Bonello diagram shows a couple of issues, and the modal spread isn't nice. You might want to re-think those dimensions. I'd make it a bit longer, extending it into the live room a bit.

I think I got the design of the control room right, but I´m not sure about the Live Room, I splayed one of the walls about 8 degrees for flutter echoes, do I need to splay more walls?

I'd angle one more, probably the one at the top of your diagram. You don't NEED to do that, but it would help, and I think it would look good, too. Have you decided on treatment for that room, yet? Also, you have some serious flanking paths between the two rooms that you need to get rid of. The inner-leaf side walls from both rooms are shown as being continuous through the gap between the rooms. And your sound-lock is a three leaf major problem! I'd re-design that if I were you. Next, your soffit panels seem to be too small. I'd re-design those to make them larger, and perhaps even make the window smaller. That's a LOT of glass you have there! Very nice, yes, but very expensive if you want to approach STC-76.

Are the the walls/ceiling assemblies good enough for my purposes or do I need more inches of air gap or rockwool, I think I have a little more space I can spare.

The shell around the studio seems to be pretty good, but you are going to need better isolation on the dividing wall between the CR and LR, which implies that you are going to need more drywall all around. You can't just add more drywall to that one section, since sound will "leak" around from the other sections. So you might need to go with three layers of drywall all around in your inner leaf. I'd also go with at least a ten inch gap for that dividing wall, since you are going to need as much depth as possible between the two panes of laminate glass, in order to keep your isolation up high. You'll need to do all the math to calculate your depth and masses on those walls, but I'm guessing that 3 layers on each side should be enough (that includes the ceilings). This is going to be a pretty massive build! Have you considered the possibility of importing a couple of cases of Green Glue? It would be expensive, but probably worth it if you need that much isolation. What plans do you have for the floor?

all the gypsum is suspended with acoustic hangers through a hat channel.

I don't think I'd do that, considering the earthquake issue. You don't want your inner-leaf ceiling and inner-leaf walls moving independently: that is a recipe for major damage. To be honest, I'd go with supporting the ceiling directly on the walls, and I'd use metal strapping of some sort between the joists and top plates, to keep things firmly tied together when the ground shakes. If you can, I'd also change the metal studs to wood: it seems to hold up better in earthquakes, as it flexes more evenly and doesn't buckle. Thinking out loud: considering the whole seismic thing, I'm wondering if it wouldn't be a good idea to replace the first layer of drywall on the inner-leaf walls with 20mm plywood or OSB. That would give you much better structural integrity for the entire build, since your entire leaf would behave very well in sheer. You'd also have the advantage of having a nailing surface around the entire room. So I'd go with one layer of plywood or OSB directly on the studs, then a layer of 16mm drywall, Green Glue (if you can afford it) and a final layer of 16mm drywall. That will give you good strength and good isolation together. And for the ceiling, just lay it directly on top of those walls. That way, everything will move as one single unit the next time an earthquake rolls by. - Stuart -

The design is for isolation and internal acoustics, I told them many times that I want to play drums at night without disturbing the neighbourghs,so an isolation level of 80db or more would be recommended. A few weeks ago I told them to explain me the design because it doesn´t seem that I will get the isolation I required they told me that I don´t have to worry that it will work and if it doesn´t we can fix it as we go or reinforce it later with no technical explanations about STC, reverb times or internal acoustics. In my opinion they don´t know how to properly treat a recording studio and the project was treated with no importance as sometimes they didn´t returned my calls for several weeks. Now I will have to design the studio on my own, I have to read and study a lot, and ask for some suggestion here at the forum.

Hi Stuart Thanks for the recommendations, I´ll apply them to the design in these days One thing I don´t get is the difference between the pink fiberglass and rigid fiberglass If I use the pink stuff for the inner walls and ceilings it should be 12-20kg/m3 and if I use rigid fiberglass it should be 40-48kg/m3? Eddie

yes on the insulation question. per Stuart's notes on earthquake concerns - you do need to add sway control to the suspended ceiling to make sure it stays in place relative to the rest of the building. you can do this by using tie cables between isolators, this forms like a truss if you will and is tied on the end isolators on the side walls. I think if you search around this site, Rod has an excellent example of this in one of his drawings. probably best to consult a structural engineer with experience in this to assess your plans. i'd do the angles in the live room with more smaller treatments rather than one large wall.

they told me that I don´t have to worry that it will work and if it doesn´t we can fix it as we go or reinforce it later

:shock: That would be pretty hard to do! Fixing isolation afterwards would mean tearing out all of the treatment first, and re-designing the entire room! No wonder you don't trust them. Well, at least you are in the right place to get help in designing it! - Stuart -

I modified the control room ratios, I can´t get the space to work with Sepmeyer, Louden or any other of the recommended ratios, but I found a paper from Standford University published in AES Journal (June 2004) which gives second best room ratios http://www.acoustics.salford.ac.uk/acou ... ntent=best so I´m going with a ratio of 1, 1:54, 1:66 (3.7m, 5.7m, 6.14m) I´m still working in other aspects of the design, I´ll keep you updated Cheers Eddie

That's still not a very good ratio, Eddie. You have mode bunched close together in the low end, with large gaps between them. Also, I'm looking at that paper and I can't see that ratio you mentioned anywhere on it! Where exactly did you see it? I just want to check something here: What are those dimensions referring to? Are those the size of the room as it is now, which is just the outer leaf, or the size of the inner-leaf that you are designing? Also, I wouldn't use the Real Traps mode calculator: as far as I know, it does not take into account tangential and oblique modes: it only considers axial modes. Use Bob Golds, or one of the others that considers all types of modes. - Stuart -

Hi Stuart Here is the link to the file with the ratios http://www.acoustics.salford.ac.uk/acou ... d_best.zip the dimensions are for the outer leaf (from inside the room) I can´t change the height of the room is going to be always 3.7m and the width is going to be always 5.7m, the only measure I can change is the length of the room, unless I redesign completely the position of the control room and the live room.

Here is the link to the file with the ratios

I already saw the file! I just could not find the ratio that you mentioned! Maybe I'm just not looking on the right page, but I can't see "1, 1:54, 1:66" anywhere in that file, and in any case plotting it on the graph they provide places it right in the middle of the white area, which is the worst rating.

the dimensions are for the outer leaf (from inside the room)

Then you are using the wrong dimensions! The room ratio is calculated for the INNER leaf, not the outer leaf. It refers to the inner solid, rigid massive surfaces of your MSM system, meaning the inside surface that faces the room on the inner leaf. Not the outer leaf. Those are the surfaces that the sound waves interact with, and those are the surfaces where your modes terminate.

I can´t change the height of the room is going to be always 3.7m and the width is going to be always 5.7m, the only measure I can change is the length of the room, unless I redesign completely the position of the control room and the live room.

You need to re-figure your ratio based on the inside dimensions of the inner leaf, and you DO have control over all of those. You can move the walls and raise or lower the ceiling, as needed. In fact, you have a good amount of space there, so you might even want to consider splaying your walls and ceiling, and also creating a proper RFZ around the mix position. A lot of folks here would kill to get a nice large space like you have! :) You have a good opportunity for doing something really nice with that space. - Stuart -

Still working on the new dimensions :D

Hi, The studio project was on hold for a few months, I´m ready to work on the design again. The control room dimensions are 3.2 x 4.48 x 6.08 meters (Louden Ratio) and the live room is 3.3 x 5.28 x 7.689 meters (3rd Sepmeyer Ratio). Now about the inner structure can I use steel beams(H form) and columns (U form) with 1.2 cm (0.5") width (I guess that´s the gauge) for the core structure. The rest of the structure would be wood or normal steel framing. Three layers of 5/8" is a great load especially for the ceiling, normal steel framing won´t do it and wood is a bit expensive so I was considering this option. What do you think?

Can you post an example of how the steel beams and the walls would interact with each other? An example of what I am asking for would be this. Will the interior wall assemblies be connected to the overhead ceiling supported by this beam? And if so, will all the ceilings be connected in the same way or will the individual rooms be decoupled from each other?

Here´s a rough example with main structure made of steel beams and columns and the rest of the frames made of wood. The structure is completely independent from the outer walls and ceilings, it will only support 3 layers of drywall, and also all the rooms are fully decoupled from each other and they will not share any beams or columns. I want to know if I can get away using steel beams and column for the core structure with a thickness (gauge) of 12 mm, or what´s is the maximum gauge I can use for steel framing?

I can tell you that this is going to be a very rigid structure. I will not say if you >can< do it since that has to be verified locally based on your gauge and materials used and the loads either imparted on the one or placed on the other. I can also say that this is going to be a difficult thing to bring about. With a simple metal structure designed to support the ceiling, that is one thing, but to attache the stud framing to the metal, that is another, and the project, while doable, is going to be a challenge. I also understand that you are in an area prone to earthquakes. So you will have to get someone involved to spec this job since the posts have to be bolted to the concrete slab, the framing will have to be bolted to the concrete slab and the ceiling in question has to be able to do a fair amount of being able to support itself under static and violent loads/seismic events. These are not answers that can be given directly from anyone here.

Thanks for the reply xspace, I´ll do some more research on the options I have for framing. I still think the best option is wood, maybe I will have to pay the extra cost.