Mixing Room

Hello everybody, First I'd like to thank you for your comments, ideas, suggestions, etc. I have read the forum rules. I apologize if there's something I do wrong. I am located in Spain, in the country side. I just bought a house. It's completely detached and there is very little noise around. It's a modern house, built in 2008. The room is in the basement, next to the garage. The external wall (thicker) is reinforced concrete. The inside walls are 1/2 foot brick. The floor, at present is covered with tiles. Right above the room is the kitchen and the entrance hall. Next to it is the garage and the house stairs (it's a 3 floors house). Originally the room was square, but we expanded it into the adjacent toilets gaining Length and creating a rectangle. We also moved the door from its original location (see photos) to a more suitable one to allow bass traps (see floorplan). I still haven't had a chance to take photos of the new rectangular space, but I'll add some in a couple of days when I'm back there. So the shots at the bottom are of the original room, just to give an idea. The room is H2.5m x W4.5m x L6m Soundproofing targets are basically the other people living in the house. I get to mix quite different material from a classical string quartet to a hardcore band. I would like to avoid disturbing the rest of the house and be able to mix undisturbed. I usually mix at very different levels from very quiet to loud (seldom VERY loud). I use Avantone Mix Cubes, Yamaha HS80s and crappy computer speaker sometimes. I mainly mix using a SmartAV Tango, some plugins, and lots of outboard. I would like to install Air Conditioning with an external compressor in the near future. The furniture, I have not decided yet. I need to fit a cupboard for my guitars, mics, cables, and all sorts of stuff, but I haven't designed that part yet. I'm trying to focus on soundproofing to then go into studio design after. I quite like John Sayers' ideas and plans, so I'll probably be looking for something similar. I would like to have some advice on how much soundproofing is really necessary. I have called an acoustic engineer and his advice was basically to create a room inside the room: Option1 Floor: acoustic membrane, concrete slab, wood floor Ceiling: ceiling made of single 16mm gypsum boards hanging from metal "springs", filled with 70kg/M2 rockwool. The ceiling wouldn't touch the walls Walls: double 20mm gypsum walls on metal frame, 70kg/M2 rockwool. The walls are placed between ceiling and floor. No contact with room. Double window Option2 Room surfaces covered with a material called Copopren (high density conglomerate of poliuretane), then a gypsum board layer. Everything is glued. Apparently the advantage of Option2 is space, especially Height. I'v been asked 10000 EUR for this kind of work. So my main questions are: -Do I need to spend that much money? (can I do with "less" soundproofing?) -Any alternative ideas/solutions that come to mind? I hope I have given enough info. Thanks for your time and input

Hola, y bienvenido al foro! También hay un foro en español aquí, pero parece que tu inglés es excelente, y hay muchos mas participantes aquí en inglés que español. So, a couple of things about the approach proposed by the acoustician that you spoke to: First, let's do what he apparently did not do: Examine the real numbers. The amount of isolation ("soundproofing") that you need is pretty large. You say you will be recording full hardcore rock bands in there, which implies acousstic drums, bass guitar, etc., so we are talking about sound levels of around 120 dB in your studio. In order to just "not be annoying" to others in the house, that needs to come down to somewhere around 55 dB at the place where the "other people" are, and in order to meet most municipal noise codes, it would have to come down to around 40 dB. So you are looking at isolation of around 65 to 80 dB, if those are your goals. That is doable, but is not easy, and will not be accomplished using the approach your acoustician quoted. His approach will give you something like high 40's to low 50's. You didn't say what the floor above the room is made of, but I'm assuming that it is either a concrete slab, or it is standard wooden construction, with joists, subfloor, and finish floor. However, your acoustician is right about one thing: the only way you can get that kind of isolation is with "room in a room" construction. This implies that all your walls are two-leaf MSM walls, with lots of mass on each leaf and large air gaps. So he's right about the basic concept, but not about the method. Let's take a closer look: First, he says that you need a floating floor. Maybe you do, but what he said is not necessarily going to give it to you: "Floor: acoustic membrane, concrete slab, wood floor". It all depends on what he means by "acoustic membrane" and "wood floor". But apart from that, you don't have the budget to do a proper floating floor. You might want to spend some time reading through this thread, so you can get familiar with the concept and the issues: viewtopic.php?f=2&t=8173 So, since your budget probably doesn't go far enough to do a floating floor correctly, and you don't have enough ceiling height to do it anyway, it seems like you are stuck with the floor that you have. But it isn't all bad news: Since you say that the external walls are concrete, I'm guessing that the floor of that room is also concrete, resting directly on the ground. That's good. It probably doesn't need any treatment, and you can either leave it as plain concrete, or stain it for aesthtics, or maybe lay something thin and hard on it, such as ceramic tiles, laminate flooring, or something similar. Keep it hard and reflective. You already have ceramic tiles, so if you happen to like those ones, then your floor is already done! :) Since you will be recording acoustic drums and bass amps in there, you might have an issue with impact noise getting into the floor, so you will probably need to build a drum riser and isolation pads for amps, to help with that issue. This somewhat reduces the need for a floating floor. Next, you need two-leaf MSM walls. You already have the outer leaf (the concrete walls of the building itself), plus the brick walls to the internal rooms. Those are fine. So you only need to add the inner leaf. That should be done with 2x6 wood studs, spaced 24" OC (60 cm), with two layers of 16mm drywall on only ONE side of those studs and 100% coverage of Green Glue between the layers of drywall. The framing should be done such that there is a gap of at least 6" between the existing walls and the surface of the drywall that faces the existing wall. You fill that gap with insulation, such as fluffy pink fibreglass or mineral wool. Then, the ceiling: This should also be two-leaf MSM. If you have a concrete slab up above you, then that's fine as your outer leaf. If you have a wood floor up there, then you might need to "beef it up" (add more mass to it) in order to make it into a good outer leaf. The inner leaf needs to be done just like the walls: wood framing (joists) dimensioned correctly for the load and span, and resting ONLY on the inner-leaf walls. No contact at all with the existing outer-leaf walls, or with the existing outer-leaf ceiling. Once again, you need a large air gap and two sheets of 16mm drywall. However, you don't have much space up there, so you could go for a smaller gap and more mass, such as a 4" gap with three sheets of 16mm drywall, to get you roughly the same isolation. This gap is also filled with insulation. You don't need windows by the looks of it, and that is great! Less weak points. But you do need doors. Build them like Rod outlines in his book. You also need to consider your HVAC and electrical installations, and they need to be designed and done very carefully in order to not compromise the isolation of the room. If you do everything right, this construction should theoretically get you isolation on the order of 65 db or so, which is the minimum you need. To get that up beyond 70, you'd need to leave larger air gaps all around and add more mass to the walls and doors, but I think you'd already be getting up to the flanking limit of the floor, so I doubt it is worth going that far. Going back to the approaches that your acoustican recommended, #2 is not going to get you anywhere near the level of isolation that you need. There are no "magical" acoustic materials that can beat the laws of physics. Those laws of physics state that the only way to stop sound is to totally decouple the path mechanically, and place massive air-tigh barriers along the path. #2 does not accomplish that. And #1 is way off base as well. Putting "double 20mm gypsum walls on metal frame" for the walls and only "16mm gypsum boards hanging from metal springs" for the ceiling is pointless! That would be like trying to build an aquarium using thick glass for the sides but cardboard for the bottom! How well will that hold water? For acoustic isolation, the entire envelope MUST be treated to the same level: All six sides of the room must have the exact same level of isolation. If one side is weaker than the other five, then you wasted a huge amount of time and money on the other five sides, because sound will simply "leak" through the weak side, and not even bother with the five "good" sides. Physics says that sound will take the easiest path out of the room. In this case, it will take the path through the thin 16mm ceiling, so the 40mm drywall on the walls is pointless.

filled with 70kg/M2 rockwool.

Way too dense! Optimum density is about 40 to 50 kg/m3. Going up to 70 kg/m3 will reduce isolation in lower frequencies, such as drums and bass guitars, which is where your biggest problems will be. Higher density is better for high frequency isolation, but you will not have any problems there! Low frequencies is where your problems will be, and for that you need lower density insulation in your walls and ceiling. Take a look at this report to understand the issues here. Three more comments: 1).

Double window

Window? What window? I don't see one on your layout, and you didn't mention it elsewhere. 2). What are you planning to do with that space under the stairs? 3). How do you plan to lay out that room? Maybe do a model in SkethUp so that we can see which way around you plan to have things, and maybe offer some advice on how to improve that. - Stuart -

Stuart, Thank you very much for your answer and compliment :) First of all, I need to clarify that my intention is to use the studio as a MIXING room only, hence the title of the thread :mrgreen: I can end up recording some stuff in there but I strongly doubt I would ever record drums (My wife would simply KILL me...). The ceiling is reinforced concrete, like the external walls ("forjado") I think that by "acoustic membrane" he means a layer of copopren or this kinda stuff http://portal.danosa.com/danosa/CMSServ ... g=1&site=1

then your floor is already done! :)

Now that is really good news cos I began having nightmares with that floor!! :)

You don't need windows by the looks of it, and that is great! Less weak points.

I do have windows (see photos). The thing is: do I need them? If I put a double glaze window in front of the original, wouldn't that be ok?..just to have some natural light.... :)

Going back to the approaches that your acoustican recommended, #2 is not going to get you anywhere near the level of isolation that you need. There are no "magical" acoustic materials that can beat the laws of physics. Those laws of physics state that the only way to stop sound is to totally decouple the path mechanically, and place massive air-tigh barriers along the path. #2 does not accomplish that.

So there is not a way to lower the ceiling less than the 15cm you suggest? Because if I need to hang a cloud too for sound treatment it's going to be really tight...

And #1 is way off base as well. Putting "double 20mm gypsum walls on metal frame" for the walls and only "16mm gypsum boards hanging from metal springs" for the ceiling is pointless!

That makes sense. I think he said that to keep the ceiling as high as possible, but of course it won't work and it will be the way out for the sound waves...

2). What are you planning to do with that space under the stairs?

I was hoping to use it for noise generating devices, such as the computer, hard drives, etc, but I'll need to create some ventilation for it, possibly into the laundry...

3). How do you plan to lay out that room?

Something along these lines but with a different vocal booth or no booth at all: http://johnlsayers.com/Stuff/Small_Studio.skp http://johnlsayers.com/Stuff/components.skp Thanks again for your time and comments. If you have other ideas, now knowing it's going to be a mixing room ( :wink: ), please do chime in. Your tips and links were very useful. I will check Rod Gervais' book (that I incidentally bought a few months ago :mrgreen: ) Cheers Pabz

If my floor is done and I build MSM walls and ceiling, I need to seal the boundaries between walls and floor, is that correct? Thanks

Absolutely! Sealing everything is a big part of maximizing isolation. Even a tiny crack between wall and floor can ruin your isolation. Seal everything that might possibly have any kind of air passage through walls. And even if you think it cannot possibly have any gap at all in it, well seal it anyway... :) - Stuart -

Soundman2020 wrote:

Absolutely! Sealing everything is a big part of maximizing isolation.

It is a part of the studio builder's coat of arms. :P The other portion refers to no triple leaf. Graphically, Andre

Thanks for your replies, but I need a couple more details clarified to go ahead. Just as a recap (in case I haven't done my homework properly) and if you guys don't mind: My floor is my friend, because it is as close as one can get to the biggest sound sponge one can dream of: planet Earth. So, I shall not touch my floor and ruin my pocket and break my heart unnecessarily. My walls are great because they are made of brick and concrete but they need a little MSM friend (or brother). My ceiling shall be the same as my walls. Everything will be sealed to death. My door will be an MDF monster. I will be very happy :mrgreen: So far so good. Rod Gervais writes that when working with gypsum walls, not all metal frames are equal. Concerned about this, I checked what they sell locally and what I found is called Pladur. The frames are basically 2 types: -U shaped that go horizontally at the bottom and the top of the wall, like a channel. These are screwed into the floor and into the hanging ceiling. -H shaped that go vertically, like studs, with holes to give way to electricity, plumbing, etc. These are screwed to the U shaped ones, on the sides. -There is also something called "acoustic tape" which is supposed to go between the floor and the bottom U shaped channel to "decouple" (I wonder how as the U shaped channel is screwed into the floor, but anyway...I don't care cos MY floor is MY friend....) The chosen insulation goes in between the metal studs and then gypsum panels are screwed onto the H shaped frame. The overall frame thickness would be suitable for 50mm thick Rockwool panels. My guess I can put whatever thickness you like since I'm building a two-leaf with the brickwall anyway. So, my first question would be: is this metal frame system usable at all or is it actually decreasing isolation? If so, I guess I should go with timber, correct? I'm asking this as I can't stop thinking about it after reading John Sayers:

* Except for staggered stud systems, substituting timber studs for steel studs generally results in a significant decrease in sound isolation. * Increasing the thickness of steel studs from 0.55BMT to 0.75BMT or 1.15BMT will decrease sound isolation * Decreasing the stud spacing will decrease the sound isolation.

After reading again and again John Sayers' "Recording Manual" (well the "Studio Design" part, anyway) I realized what he was talking about when describing "his wall" and why it would be half as thick as a "normal wall". If I got this right, basically isolation and treatment are "merged" in one system, is this correct? If so (and my floor is still good) then I could follow Sayers' concept with a little variation: This is the original John Sayers diagram: The little variation, although the air gap would be as thick as the insulation: If the variation is ok, I would only need to build it either A) Using the metal frame to hold the double gypsum layer and the inner insulation. I'd have to find a way to glue the insulation next to the air gap. OR B) Same as A but with timber studs in case the metal frame is a no go. So, resuming, is the variation ok? Is the metal frame a no go? Again, thanks for your comments and ideas. Tackling the ceiling after some sleep :mrgreen: Cheers

Anyone knows what the "fluffy pink stuff" is called in spanish or how to search for that? Cheers

I don't mean to sound unpolite or ungrateful here, but I don't get this. I know people are busy, just as I am myself, and there's plenty of people posting on this forum, but I really don't have the impression I haven't followed the posting rules not to get anymore replies (if I haven't, I sincerely apologize but I could do with a hint too) just when I'm getting to something and I find myself stuck with these questions. I was hoping to get some answers to move onto other aspects of studio building. TBH I was expecting to talk about not only walls, but windows, doors, treatment, hangers, etc....is there something else I'm missing or I am simply boring?

Anyone knows what the "fluffy pink stuff" is called in spanish or how to search for that?

Not sure what the building standards are in Spain, but in the US it is just standard fiberglass insulation - typically sold in bats or one long roll.

bwilkinson wrote:

Anyone knows what the "fluffy pink stuff" is called in spanish or how to search for that?

Not sure what the building standards are in Spain, but in the US it is just standard fiberglass insulation - typically sold in bats or one long roll.

Thanks a lot for your answer bwilkinson :) I would like to use it to fill the airgap. Any suggestions on how to hold it, or it's not even needed, you just pile it up? Cheers Sono

Anyone knows what the "fluffy pink stuff" is called in spanish or how to search for that?

Here in Chile it is called "lana de fibra de vidrio" or simply "lana de vidrio". Here are some examples: http://www.easy.cl/easy/ProductDisplay? ... &caN3=2507 http://www.easy.cl/easy/ProductDisplay? ... &caN3=2507 http://www.easy.cl/easy/CategoryDisplay ... 7&pagina=1 Also, mineral wool is "lana mineral": http://www.easy.cl/easy/ProductDisplay? ... &caN3=2507 - Stuart -

I would like to use it to fill the airgap. Any suggestions on how to hold it, or it's not even needed, you just pile it up?

If you use "unfaced" insulation (no paper on one side) under normal construction, then it is just a friction fit between the studs. Again, using US standards, it comes either in 15" width (for placing between studs on 16" center), or 23" width (for placing between 24" centers). If you use "faced" insulation (which has paper on one side), then the facing can be stapled to the studs. In your case in which you are using inside-out construction between gypsum and brick, to be honest I don't know. I haven't tried yet.

My floor is my friend, because it is as close as one can get to the biggest sound sponge one can dream of: planet Earth. So, I shall not touch my floor and ruin my pocket and break my heart unnecessarily. My walls are great because they are made of brick and concrete but they need a little MSM friend (or brother). My ceiling shall be the same as my walls. Everything will be sealed to death. My door will be an MDF monster. I will be very happy

Yup! That's about it! Regarding the wood vs. metal issue, I'm really not certain. I've never looked into it, because I don't like working in metal, and I do like working in wood! :) I hope someone more knowledgeable can comment on that aspect.

The overall frame thickness would be suitable for 50mm thick Rockwool panels. My guess I can put whatever thickness you like since I'm building a two-leaf with the brickwall anyway.

Yup! Here "more is better". If your building code (and your budget!) allow you to fill the entire cavity, then go for it.

If I got this right, basically isolation and treatment are "merged" in one system, is this correct?

Yup, that's pretty much it. You do have to realize that the two-leaf is a tuned system, and whatever you change has consequences. So if you reduce the size of the air cavity, that increases the resonant frequency, which is not good. To compensate for that, you can increase the mass of the leaves, which reduces the resonant frequency again, which is good. But there are limits: you can't go down to much less about 3" inches or air gap, or if you do then you need a LOT of extra mass to compensate. And going the other way too much also isn't good: For example, if you go to a 16" air gap then theoretically you could go with just a single leaf of 1/2" drywall (12mm), but 1/2" has its own problems, such as being too flexible and having a high resonant frequency all of its own, so you wouldn't want to to do that. So you'd still never go less than a single layer of 5/8" (16mm) drywall, no matter how big your air gap is. But I'm waffling... That's just a long way of saying: Yup, your variation on John's design is just fine. The slot wall is a very effective way of treating the room, too.

I'd have to find a way to glue the insulation next to the air gap.

Gluing it is probably not a good idea. There are special "spikes" that you hang it from. You attach the spikes to the wall, and push the insulation onto them. - Stuart -

Thanks, thanks and thanks again :mrgreen: That clarifies all I needed to sort out walls, floor and ceiling. I am trying to sketchup the room to give you a more precise idea, because I still have one problem to sort out: the window. I'll get back when I can give you proper info. Thanks again for your time and help Cheers Sono

I've sketched up the bare room before any isolation/treatment etc. I pictured some ducts present in it. Some are in gypsum boxes which I'd probably better take out and cover the ducts with insulation. I also thought of changing the shape of the ducts to avoid water falling directly. Something maybe like a zigzag? Maybe it's not necessary with insulation as it won't be really LF, right? The concrete square is a well with a pump in it. All the water from the house ends up here and is pumped into the main sewers. The pump is very silent, or at least I didn't manage to hear it. The concrete block is probably not a problem, but I was wondering if the cover, made of metal (it's like a sewer cover but square shaped) could be a problem and if there is a solution for that. The rest of the floor is all tiles. So to make it nice I thought I could cover the whole thing with something like Ikea Floor. I finally decided to close the cavity under the stairs and open an access from outside, so that I can use it for the noisy machines such as computers, etc without compromising isolation. The channel that has been dug in the concrete floor will be covered in insulation and sealed. Is this door ok to build or should I stick to the SuperDoor? viewtopic.php?f=2&t=12664 All input is very welcome and appreciated as usual :) Thanks Sono

Today I learned what the ceiling is made of: from bottom (studio ceiling) to top (kitchen floor) 1 cm plaster 40 cm thick layer of concrete beams (40 cm wide) and hollow bricks (60 cm wide) 5 cm reinforced concrete (with steel bars inside) as compression layer 10 cm of cement 1 cm tile glue 1 cm tile Do you reckon that's a good starting point? Cheers Sono

Nobody? :snack:

While I wait for some replies, some new photos as promised :mrgreen: The cavity, as seen from the studio. I decided to make this a "machine room". To insure isolation, the cavity will be closed on the studio side and the wall under the stairs has been demolished to provide access from the outside. This is what my brick walls look like in section. The concrete ones are much thicker. The cavity wall as seen from the studio. You can see the duct on top. To the left, the old door, now sealed. Opposite wall. To the right I will install the new door. From the engineer point of view, this would be left-back corner. The ducts on top right are the house discharge to the sewers. Final bit is the vertical big duct at the center of the photo. I am now building a cement thingy around this vertical duct because the discharge hits the bottom of the tube causing noise. The rest will be covered in wool and hopefully noise free. To the left, opposite the door, this would be the back-right from the engineer position. I'll give up the small window, but I'll try to keep the big one...money, money, money.... The window I want to keep. On top of it, electricity. Concrete walls Section of the wall on the left from engineer's position (opposite windows), boundary with the garage. This is where I'll put my door... Detail of ducts going into ceiling. You can see the ceiling composition...well, a bit...40cm thick of alternating concrete beams and big hollow bricks. My plasterboard ceiling will hang from the concrete beams through springs. Metal trap to access the pump in the well. I learned this afternoon that this pump works only for the old toilets and for the water that falls from the garage ramp into the garage. In other words, it will never be active unless it rains like hell.....considering I'm in Spain... I will need to dampen the metal cover though to avoid resonances. My best pal...all dusty due to demolitions at the moment...but always by my side :mrgreen: Cheers Sono

I've taken the John Sayers basic studio layout. How is this as a starting point? Please let me know your thoughts Cheers

Basic idea looks fine, but you can straighten it out a bit and make some better use of space. John had to sacrifice space with that design to fit all of it into a very small area, but your area is larger, so you don't need to do that. You can make better use of space, I reckon. - Stuart -

Ok. I'll try to rework it. Any suggestions are welcome though :mrgreen:

I was thinking that this wall and the adjacent one (old door/cavity) are very different from the other two (thinner and made of bricks whereas the others are reinforced concrete), and are actually INSIDE the house. Would it be a good idea, before building the isolation layer, to reinforce their mass with either: -glueing/screwing one/two layers of drywall on it? -add a gypsum/cement cladding to the brickwall (about 1-2 cm thick)? or would this not change much? The present layer of gypsum is about 1 cm either side. Thanks for all input

sonolink wrote:

Section of the wall on the left from engineer's position (opposite windows), boundary with the garage. This is where I'll put my door...

Image not preserved: Foto 18.jpg