3 Studios in a Basement

You sure have some good wine too in Chile

Black are existing walls, ... Blue walls are the outer walls (internal partitioning) that we need to build. ... Then we'll build the inner walls for each studio & vocal booth.

We are in Dance Music, so that means a lot of kick drums & bass lines ... I would say an overall level of 90dB

so we decided to go for a -45dB insulation goal

with a floating room (room in room) design.

The outer wall of the basement (The 4 walls around the whole 200m2 space) are made of bricks. ... The ceilings are concrete between joists. ... The floors are concrete too and some tile.

- Existing outer walls being bricks, I found a post explaining how to seal with polyurethane + expansing foam, and finish with a 16mm plasterboard.

Question : do we apply directly this plaster board on the bricks with a RC channel and screw it on the RC ?

shall we put an insulation between brick & plasterboard to avoid creating air in order to keep that 1st layer as a "1st mass leaf" ? or we just do the seal with polyurethane + expansing foam and we forget the 16mm plasterboard ?

- We only have 4 walls, (the ones up/down + left right on the pic), that means that we have to build all additional internal walls to create each studio space (internal partitioning).

what do we use ? plain plaster block ? plaster blocks with cylinder holes of air inside ? or a first metal stud made with plasterboard 16mm + metal stud & Batt insulation + 16mm ? or something else ?

Once these internal walls would be ready, we would end up with the C/B/D space like on the attached pic. There comes my nightmare about the inner walls for each studio.

We have found 45db steel acoustic doors (Width 1120 / Height 2400) : 6700 USD :(

on which layer do we attach it ?

so we'll just go for the "floating cosmetic floor" with wood stud on neoprene pads + insulation between them & double plywood + parquet floor on top.

so does the floor goes "inside the walls" or underneath the walls ?

understood the concept with joist on the inner walls and nothing attachedn not touching the actual ceiling. That means fat walls to handle the ceiling and the steel door.

with a floating room (room in room) design.

The outer wall of the basement (The 4 walls around the whole 200m2 space) are made of bricks. ... The ceilings are concrete between joists. ... The floors are concrete too and some tile.

- It would probably be better to stucco (plaster) those walls if you think you need more mass on them, and then seal them with some type of concrete sealer, that you just paint on. ok, we'll do that on existing wall and also on the new outer walls we need to build (red lines)

Question : do we apply directly this plaster board on the bricks with a RC channel and screw it on the RC ?

I'm confused: I thought you were talking about sealing your outer leaf? Why do you want to put RC on it????? In any event, you should not EVER use RC over a thin air space, as that would give you a very high MSM frequency, and therefore really bad isolation. If you plan to use RC, you need a lot of air gap behind it. But you seem to have plenty of space to build decoupled walls, so I don't see why you want to use RC at all. It doesn't make sense. I thought it was good to put one layer of plasterboard on the outer walls, to add more mass and start with a flat clean surface. but ok, just stucco/plaster for the sealant ;)

shall we put an insulation between brick & plasterboard to avoid creating air in order to keep that 1st layer as a "1st mass leaf" ? or we just do the seal with polyurethane + expansing foam and we forget the 16mm plasterboard ?

I think maybe the confusion is on your end, not my end! :) OK, let me explain: in order to isolate your studios, you need ONE outer leaf that goes around all of them: that is your existing concrete walls, floor and ceiling. Period. It doesn't need anything else on it, except for sealant (to seal the porous surface of the bricks and concrete). That is your complete outer leaf. End of story. No foam, plasterboard, RC, or anything else. Just the plain, existing concrete and brick outer leaf. (We'll talk about doors, windows, HVAC, and cabling later) Within that outer leaf you then build each room as a single leaf, not touching any other room, and not touching the outer leaf. In other words, for each room you build a stud frame with drywall (plasterboard) on only ONE side. You might need two or more layers of drywall, but they will all go on the same side of the studs. That is your inner leaf for each room, period. There are no more walls. End of story (not yet considering doors, windows, HVAC, cabling...) ok for that stud frame we plan to do 3x16mm plasterboard on studs of 95x35mm. would that be good to reach our aimed 65 dB TL ? That's it! Each room has it's own single inner-leaf, and they all share the existing outer leaf. ok :D last but not least : how many cm of air do we put between our inner leaf and the outer leaf (in other word between concrete/brick walls and the first layer of plasterboard) ? do we fill that air with isolation ? in that air space is it ok to have electricity conduits and ventilation conduits if nedded ? But no matter which method you use, you still need only one leaf around each room, thus giving you full 2-leaf construction. ok, so according to my layout, once we'll have built the walls of the red line, seal them to the existing one, creating only pretty decent, massive outer leaf, we just build each room inside made of studs & plaster boards and keep them separated one from each other, individually sealed.

so we'll just go for the "floating cosmetic floor" with wood stud on neoprene pads + insulation between them & double plywood + parquet floor on top.

It works quite well (I think),

Right now, we're focusing on what do we make the outer wall of ? (the red lines that does not exist today and that we need to build to finish our outer wall) - Plaster blocks of 5, 7 or 10mm ? or - Concrete block (filled, not empty with air in the middle) of 10, 15 or 20mm ? or - OSB wood panels : 70mm + coating (http://en.wikipedia.org/wiki/Oriented_strand_board)

Soundman2020 wrote:

It works quite well (I think), Weeeellllllll.... maybe not! You destroyed the room symmetry that John had in his original design! Either that, or you misunderstood the surfaces and materials in his design.... You also seem to have made the room practically square! We tried to keep the symmetry but we had to change the angle of one panel to make our door fit. is it going to be a huge problem for the room ? And yes it gets quite square unfortunately for this one, 410x335 on the speaker side, and 410x420 on the door side, but it's the solution we found to make the vocal booth fit. Do you have any suggestion that would work better ? The good thing is that for the studio D we can do the design in 600 x 400, plus its vocal booth in 240x215, so it will be easier to have a better design in there.

Right now, we're focusing on what do we make the outer wall of ? (the red lines that does not exist today and that we need to build to finish our outer wall) - Plaster blocks of 5, 7 or 10mm ? or - Concrete block (filled, not empty with air in the middle) of 10, 15 or 20mm ? or - OSB wood panels : 70mm + coating (http://en.wikipedia.org/wiki/Oriented_strand_board)any reason why you don't want to use plain old drywall? Also known as "sheetrock" "gymspum board" and "plasterboard". yes, because that's outer leaf we are talking off, so we are aiming for one good mass and there willl be more mass if we use 7cm or 10cm plaster blocks or concrete blocks filled rather than 2 or 3 x 16mm plasterboards. for inner leaf we will use plasterboard and wood frame. But I see why you asked, my bad : I wrote : Plaster blocks of 5, 7 or 10mm ? it's in fact Plaster blocks of 50, 70 or 100mm same for concrete, my proposal is to use Concrete block (filled, not empty with air in the middle) of 100mm or 150mm I also noticed that these two studios are entirely separate from each other, so I guess the idea is that there will be no interaction between them at all? They will always be doing totally different things, and never be working on the same project together, for example? Also, they will never need to share equipment or resources (eg. mics, cables, engineers, talent, etc.)? And none of the equipment will be located in the machine room? The reason I ask, is because that's not a good layout if there well be collaboration going on between the two studios. It would only be good if they were specifically intended to be totally separate. Yes, no interaction at all. They don't work together, different projects, even different companies. That's also why each entrance is on different side of the basement. They will not share equipment or ressources either, and only Studio D will have some equipment in the technical room. Studio B is independant, alone ;) I also noticed that you only have vocal booths in there: no live room. So you'll only ever be doing simple voice-overs and lead vocal recordings? Never any live instrument tracking, small bands, or even choruses? no, we will never do any instruments (we do Dance Music, our producers don't even know what an "instrument" is :lol: ), just kidding, I mean, they all use plug ins and synth, we just need to do voice-overs and lead vocal, that's it. No instrument to record, no band, nothing like that. Just a few questions to get you thinking .... :)

We tried to keep the symmetry but we had to change the angle of one panel to make our door fit. is it going to be a huge problem for the room ?

And yes it gets quite square unfortunately

Do you have any suggestion that would work better ?

I wrote : Plaster blocks of 5, 7 or 10mm ? it's in fact Plaster blocks of 50, 70 or 100mm

Yes, no interaction at all. They don't work together, different projects, even different companies. That's also why each entrance is on different side of the basement.

Can we use those plasterblock or concrete block for outer leaf ?

to me it sounds like a good mass and it's easy to build here ! if yes, does 70mm or 100mm makes a big difference on the outerleaf considering our goal ok 65db TL ?

Soundman2020 wrote:

We tried to keep the symmetry but we had to change the angle of one panel to make our door fit. is it going to be a huge problem for the room ?

Yes! symmetry is critical! If your room is not symmetrical, then you cannot get an accurate stereo image, and your soundstage will be distorted. People who listen to your mixes where there is good stereo imaging (eg, ear buds on an iPod, headphones, cars, etc.) will notice that the stereo is "lopsided", in one way or another. The room must be symmetrical for at least the front half.

And yes it gets quite square unfortunately

Square is bad: With square rooms, the natural room modes all line up at the same frequencies, so you will have huge nulls and peaks in the room response. Once again, your mixes will not translate well. You cannot fix modal issues with equalization, since it is a time-domain problem, not a frequency-domain problem. The only way to fix it is to have a room where the modes are well spread out, evenly, and suitable treatment.

Do you have any suggestion that would work better ?

What I would have done is to have the two studios facing each other, (left to right across your plans) with the two booths in the middle, between the studios. That gives you a lot more flexibility in the design.

Can we use those plasterblock or concrete block for outer leaf ?

Either should work fine. Use whatever has the highest density and rigidity, for the lowest cost, and whatever can be sealed best.

to me it sounds like a good mass and it's easy to build here ! if yes, does 70mm or 100mm makes a big difference on the outerleaf considering our goal ok 65db TL ?

It's not just the outer leaf that governs the isolation! And it's not just the inner leaf, either. It is both, together, plus the gap between them, plus the insulation in the gap: They all act together as a tuned resonant system. If you change any one of them, then you change the entire isolation, and not just in the total amount of transmission loss, but also in the parts of the frequency spectrum that is isolated well, and not so well. The total mass on the leaves plus the depth of the air gap determines the MSM resonant frequency (and therefore the part of the spectrum that is well isolated), the insulation determines how well that resonance is damped (and other resonances too), and all of it together determines the total isolation. Increasing the block width from 70mm to 100mm is around 50% more total mass on that leaf, so yes it is worthwhile: That will allow you to use a smaller air gap to attain the MSM resonant frequency that you need. But the important thing here is that everything works together as a tuned system, not as individual parts. The entire wall design matters, not just the outer leaf.

there is space lost, also between studios 1 & 2, there is 2 triangles of lost space between the speakers.

Here is what we got so far, see above studio 2

If we do that for the outer wall, and do 3 x 16mm plasterboards on 95mm x 35mm wood studs, how much air space shall we leave in between ? 50mm ? 100mm ?

As we are going to order the materials soon

That means to cover the existing ceiling with 120mm CSR Bradford Soundscreen (30kg/m3) or equivalent, and covered with 10mm Gyprock FlamechekMR Plasterboard. So that's 13cm gone for me

when I have a concrete joist on the ceiling, can I put a less thick soundscreen but with a higher density to save space ?

if not, that will be 13cm below the joist too

I am asking because I read that a denser insulation transmits more LF,

so I don't know what insulation to put on concrete joist

Then below this, some small air (2cm,

and then we'll do the "inner ceiling" that will lay on the inner walls with the same 95 x 35mm studs, with 3 x 16mm plasterboard on the outer part of that leaf

is it a problem to incline the "inner ceiling" ?

Soundman2020 wrote:

there is space lost, also between studios 1 & 2, there is 2 triangles of lost space between the speakers.

I think you are totally misunderstanding what you have seen on John's design! You are confusing the interior treatment surfaces of the room, with the inner-leaf!!! :shock: In other words, what you are showing in your diagram is only the final surfaces that you would see of the acoustic treatment INSIDE the room. You are NOT showing the most important thing, which is the actual inner-leaf of the MSM isolation system. Most of the treatment surfaces that you show there are simply cloth or slot walls.... Maybe you need to take another look at the model that you copied that from, and try to understand better each of the materials and surfaces.

Here is what we got so far, see above studio 2

My suggestion was to put the two vocal booths BETWEEN the two studios, not the other way around! :)

If we do that for the outer wall, and do 3 x 16mm plasterboards on 95mm x 35mm wood studs, how much air space shall we leave in between ? 50mm ? 100mm ?

What is the density of your plaster blocks? (kg/m3) There are many ways of making plaster blocks, so the density could vary wildly. I'd need to know the density of the specific blocks you are planning to use.

As we are going to order the materials soon

Ummmm.... I think you are several months away from being able to order materials!!!! :shock: You've been working on this for a couple of weeks already, and you don't even have a viable basic layout, let alone a detailed plan. And now it seems that you are having a problem understanding some of the basic acoustic design concepts used in the studios that you are trying to copy. Maybe this sounds a little harsh, but you are not ready to build anything yet. If you build something based on the way you are going now, it is going to be a disaster. If I were you, I would spend a couple of weeks studying the basics of acoustics and studio design, using the forum and the usual books that we always recommend here, then spend another couple of weeks doing your basic layout, based on the principles that you learn, then spend another couple of weeks refining that layout, and drawing the actual plans, with the correct materials in the correct places. And only then should you start thinking about buying materials.

That means to cover the existing ceiling with 120mm CSR Bradford Soundscreen (30kg/m3) or equivalent, and covered with 10mm Gyprock FlamechekMR Plasterboard. So that's 13cm gone for me

That's not enough for what you need. You say that you need high isolation between the rooms, so that's not going to do what you need.. The ceiling must be done to the same level as the walls: Same mass on each leaf, same air gap. If not, then you are wasting money on the walls! If you build walls that isolate to 65 dB and a ceiling that isolates to 40 dB, then the entire final isolation of your room is about 40 dB.

when I have a concrete joist on the ceiling, can I put a less thick soundscreen but with a higher density to save space ?

No. Increasing the density of the insulation on the cavity will not improve isolation, and in fact it could REDUCE isolation. The densities you find recommended here are on the forum are already the optimum densities, and have been tested many times in acoustic laboratories. That's the best. If you uses something else, it will be worse, not better.

if not, that will be 13cm below the joist too

Not necessarily. There are ways of compensating for reduced air gaps.

I am asking because I read that a denser insulation transmits more LF,

Exactly. Higher density is worse for low frequencies.

so I don't know what insulation to put on concrete joist

Optimum density! around 30 kg/m3 for fiberglass, or around 50 kg/m3 for mineral wool. Those are optimum densities, for most acoustic applications. You can use other densities in some places, if you understand what you are doing.

Then below this, some small air (2cm,

A 2cm air gap is WAAAAY to small. Do not ever have an air gap of less than 10 cm. Less than that and the MSM frequency rises really fast, and you can no longer compensate with mass, as the amount of mass you need is thicker than the air space you save...

But you also seem to be confused about the term "air gap". In acoustics, when we talk about the "air gap" in some type of device (such as an MSM wall, for example), then it is still considered to be "air" even if it has insulation in it. Fiberglass an mineral wool are mostly air anyway!

and then we'll do the "inner ceiling" that will lay on the inner walls with the same 95 x 35mm studs, with 3 x 16mm plasterboard on the outer part of that leaf

Did you check the structural characteristics of those joists? (not studs: joists. You are talking about the ceiling here, so they are joists, not studs). I'm not sure if you can support several tons of drywall on 2x4 studs spanning those distances.... Did your structural engineer say you could do that? What deflection are you figuring? You are talking about spanning more than 4 meters, maybe as much as 5 and a half meters? I don't see how you can do that with such a load on 2x4's!!!!! What type of wood did you have in mind?

And what are you talking about "outer part of that leaf"??? A leaf is a leaf: There is no "inner" or "outer" part to it. It simply consists of one or more layers of dense material. so the leaf IS 3 x 16mm drywall, period. That's it. That IS the leaf. There is no more to it than that.

is it a problem to incline the "inner ceiling" ?

That depends on your design concept, and the reason for tilting it, and how much you tilt it! If you are basing your room on the RFZ or CID concepts, then yes, you can tilt it, but then you need to calculate the correct angle. If not, then you still can tilt it if you want, but you'll need to use a cloud for treatment anyway, most likely. Rooms can be built rectangular, or they can be built with splayed surfaces. But those are two different design concepts, and need two different approaches to how the surfaces are treated.

And in any case, you should only angle the ceiling UP, never DOWN. In other words, the lowest point of the ceiling must be over the speakers, at the front of the room, and the highest point must be over the sofa, at the rear of the room.

(13cm insulation + 10mm plasterboard + 2cm air). I would expect something more like 10 to 15cm air-plus-insualtion, then 2 or 3 layers of 16mm plasterboard.

Anyway, the basic impression that I get here is that you are still rushing, and seem to be in a big hurry to build this place when you are nowhere near ready for that yet. If you don't have the time or the knowledge to design this yourself, then maybe you should hire someone to do it for you. Send John an e-mail or PM, and ask him for a quote. This is what he does for a living! How knows how to make the best use of space, and how to get the best acoustics and isolation in there, and get you as studio that not only sounds great, but also looks great! He's been doing it for years, and will certainly not make the mistakes that you seem to be making! He designs top-class studios around the world, and your project is exactly the kind of thing he does really well. It would be much better, and probably cheaper in the end, to pay the design fee and get it done properly. If you do it wrong, how much will it cost you in lost income of nobody wants to work in your studio because it sounds bad and the mixes don't work? How much could it cost you to tear it down and re-build it right?

Or, if you prefer to do it yourself, then I'd really suggest that you buy the "Master Handbook of Acoustics" and also Rod's book "Home Recording Studio: Build it like the Pros". Those two will teach you the theory and practice of designing studios, and once you have read them and understood them, you should be able to get started. Then you can post your design here on the forum, for folks to comment on (Rod himself posts on the forum occasionally), and perfect it, based on the comments and suggestions, just like you are doing now. That will work fine too, and it is what the forum is here for! But it takes a lot longer. :)

My suggestion was to put the two vocal booths BETWEEN the two studios, not the other way around! :)

if not, that will be 13cm below the joist too

Not necessarily. There are ways of compensating for reduced air gaps.

Exterior wall will need some caulking to avoid air cavities between the stones. Since we're in a basement and we might have humidity (not in the studio but in the air cavity of the M/A/M) we are thinking about caulking with concrete instead of plaster.

Stuart, bottom right pic is for you !!