John Sayers' Recording Studio Design Forum Archive

G’day all,

Long time listener first time caller.

I’m a Musician/High School Music Teacher based in Newcastle, NSW, Australia.

Excitedly attempting my first studio build in a 9x6m garage in my suburban backyard. The function of this room will initially be a place for me to hone my craft as a producer/composer/mixer with a view to eventually taking on clients as a ‘side hustle’ that I can hopefully one day turn into a full blown career change. I’d eventually like to be able to record a live band in this space, but I can see the main function being mixing/composing, at least in the short term.

There is already a bathroom in the corner. I’ve already looked into having John design the studio to be along the lines of WeFo studios https://www.johnlsayers.com/Pages/thirdeye.html , which is featured on John's homepage. My building is the same size, but where he has a vocal booth I have a bathroom.

Unfortunately that kind of studio is a bit out of budget and well above what I require at this stage of my career (I’m relatively new to recording/mixing).

Putting up a second wall with an airgap would probably not be an option at this point, but I’d like to think it will be in the not too distant future, so I’d like to finish off a very simple room with a view to upgrading once I am more experienced and fiscally sound….

At this stage I can afford to replace the garage door with something more airtight (glass sliding door?), block up any airgaps with some kind of sealant, insulate, put seals around the doors, install a ceiling and walls, run power points, run lights and install an aircon. My brother is an electrician, and my uncle runs an Air Conditioning company, so that will alleviate some significant expense

I’d like to do this in such a way that once I am able to have someone like John design me a room that will sound great and keep the noise out (and therefore my neighbours happy), it will just be a matter of adding to what is already there, rather than tearing anything much down and starting from scratch.

As I understand it, mixing is optimally done at around 87db to account for the Fletcher-Munson curve (sorry for sounding like a noob), so I’d imagine this is the SPL I will need to control to keep my neighbours happy.

Eventually I’d like to record live drums effectively (I imagine over 100db), but I believe that would be out of the scope of what I’m able to afford in a single walled room at the moment. At this stage a more realistic control would be just an electric kit and headphones.

This is a not-to-scale diagram of the room with all dimensions and some photos of the building. All measurement are in mm. Excuse the mess, as it's currently being used as a shed
Questions:

1. What do I need to do in terms of making this wall as airtight as possible? Do I need to fill the cracks in between the outer wall and the frame with some kind of sealant?

2. What should I use for insulation? Around the outside of the bathroom we used a more heavy duty bat than standard. I'm unsure of what is was called.

3. How would I go about best controlling the sound of rain on the tin roof? It can be quite noisy in there when it’s raining, but I assume this will be significantly reduced once a ceiling with insulation is installed.

4. I’ve seen a YouTube Video of a studio build where they put a heavy putty around each of the power outlets inside the wall, again I believe to make the room more airtight. Is this necessary?

5. Is there anything special I need to ask for when ordering a sliding door? I know the seal around it obviously needs to be air and water tight.

6. Is there anything glaringly obvious I’ve missed?

Would love any and all help anyone can offer.

Thanks in advance!

Reece

Hi there Reece,and Welcome!

Congrats on jumping in the deep end, to build your place!

Putting up a second wall with an airgap would probably not be an option at this point, but I’d like to think it will be in the not too distant future, so I’d like to finish off a very simple room with a view to upgrading once I am more experienced and fiscally sound….

Before you make major decisions like that, you should first decide on the single most important defining number for your studio: Isolation. How many decibels of isolation do you NEED, in order to be able to use the studio for what you WANT. It would be really sad to spend a lot of time, money and effort in fitting out your place, then find it is unusable most of the time because you can hear the neighbor's dog barking all the time, as well as his lawnmower, the traffic in the street, aircraft flying overhead, sirens from ambulance /police / fire in the distance, rain on the roof, wind.... you get the picture. Or even worse; the first time you use it, the cops come knocking on your door saying it is too loud, and you have to turn it off....

So your very first order of business is to define how much isolation you need, in decibels, to make your studio usable.

That number is what will define how you build your studio.

At this stage I can afford to replace the garage door with something more airtight (glass sliding door?), block up any airgaps with some kind of sealant, insulate, put seals around the doors, install a ceiling and walls, run power points, run lights and install an aircon.

That will make a nice rumpus room, or TV room.. but perhaps not so much for a studio...

My brother is an electrician, and my uncle runs an Air Conditioning company, so that will alleviate some significant expense

That's good news, but do be careful: if your brother and uncle have never done wiring or HVAC for a studio before, then they have a steep learning curve ahead of them: doing electrical and HVAC for a studio is not the same as doing it for a house, shop, office, school, etc....

I’d like to do this in such a way that once I am able to have someone like John design me a room that will sound great and keep the noise out (and therefore my neighbours happy), it will just be a matter of adding to what is already there, rather than tearing anything much down and starting from scratch.

It would be nice if that were possible, but basically you won't have any choice: you WILL have to tear down some of what you built, in order to improve the isolation:: However, if you do that carefully, you can save the materials to re-use.

As I understand it, mixing is optimally done at around 87db to account for the Fletcher-Munson curve (sorry for sounding like a noob), so I’d imagine this is the SPL I will need to control to keep my neighbours happy.

Well, yes no sort of maybe not really sometimes always never! as with most things in acoustics, there's a lot more to things than meets the eye, and a simple answer like "always mix at 87 dB" is never going to be correct. To start with, do you mean 87 dBC, or 87b dBA, or 87 dBZ? There's a big difference in how loud those three sound... Playing a contemporary rock song at 87 dBA would sound about twice as the loud as the same song played at 87 dBC...

OK, so, what you are probably thinking of is calibration. Most studios and cinemas are calibrated at 86 dBC. That's the level they are tested at, to make sure that the response is flat at that level. But that is NOT the level that you must mix at! You mix at the level that you find comfortable, and that allows you to do the job well, without damaging your hearing. Most engineers tend to mix quieter than that: maybe around 75 to 80 dBC, then they push up the level to maybe 100 dBC or so briefly, every now and then, to "check the low end". And when the client comes in to listen to the mix, then probably play it at the blasting limit or their sound system, to impress the socks off the poor guy! But most of the time, it is more sedate.

However, you should probably do some testing with a decent sound level meter, to see what levels you normally mix at (average, and also peak), and design your room for that.

Eventually I’d like to record live drums effectively (I imagine over 100db)

More like about 115 dBC, played normally. Louder when played by a gorilla...

but I believe that would be out of the scope of what I’m able to afford in a single walled room at the moment. At this stage a more realistic control would be just an electric kit and headphones.

With a typical normal house type wall, you will get around 30 dB of isolation. That's it. So your 80 dB level inside will be about 50 dB outside. That's not quiet. And when you push it to 100 inside, it' going to be 70 outside. Hmmm...

1. What do I need to do in terms of making this wall as airtight as possible? Do I need to fill the cracks in between the outer wall and the frame with some kind of sealant?

Yes. Airtight seals are critical to isolation. Even a tiny gap can damage your isolation. If it looks like a gap or crack, then seal the hell out of it. If you think it might be but aren't sure, then seal the hell out of it. And if you are certain that it is NOT a gap or a crack, then seal it anyway, just in case....

There are specialized acoustic sealants, but if you are on a tight budget you can skip those. Use a typical household caulk that is meant for bathrooms or kitchens, and remains soft and flexible even when it is totally cured. Buy a few tubes of different brands to test, and go with the one that sticks like crazy to all possible building materials, and remains the softest, most flexible after it is cured. NOt sure if you can get it where you live, but I have had good success on several studios with Sika brand FC-11 sealant.

2. What should I use for insulation? Around the outside of the bathroom we used a more heavy duty bat than standard. I'm unsure of what is was called.

Either fiberglass or mineral wool is what you need. Do not use stuff that is too heavy! That won't work so well for low frequencies. Use the RIGHT density. If it is fiberglass, then you want a density of around 30 kg/m3. If it is mineral wool, then it needs to be around 50 kg/m3.

3. How would I go about best controlling the sound of rain on the tin roof? It can be quite noisy in there when it’s raining, but I assume this will be significantly reduced once a ceiling with insulation is installed.

Not really. There won't be much difference, since you are not decoupling your inner-leaf. It will be a bit quieter, yes, but nowhere near quiet enough for critical listening. Installing a drywall ceiling will reduce the highs frequencies form the rain mostly, but the lows will still get through.

4. I’ve seen a YouTube Video of a studio build where they put a heavy putty around each of the power outlets inside the wall, again I believe to make the room more airtight. Is this necessary?

Be careful of YouTube videos about building studios! If I had a dollar for every YouTube video that wants to teach you how to build a studio, but is totally wrong, I'd be rich!

Using putty packs around your outlets only matters if you are going for good isolation. And it is not for sealing: it is to add mass around the electrical box, such that the surface density of the leaf is continuous all around the room, in order to ensure that the MSM resonant frequency is correct.
There's no need in your case, since you are not planning to isolate your studio. If you did that now, you'd have to rip it out and throw it away when you re-do it with proper 2-leaf isolation later.

5. Is there anything special I need to ask for when ordering a sliding door? I know the seal around it obviously needs to be air and water tight.

The glass must be as thick as you an possibly get it, hopefully a single pane of laminated glass, and NOT a double-glazed unit. Also check that the seals are high quality when the door is closed, with no air gaps around the edges at any point.

6. Is there anything glaringly obvious I’ve missed?

Yup! The interior design for your room, and the isolation system around it!

Apart from the isolation, you also need to start working on the layout for your gear. Specifically, the correct location for your speakers and the mix position, plus the bass traps, cloud, and first reflection point treatment. That is very important. Room symmetry is critical, and so is the correct relationship between the parts of the room.


- Stuart-

Hi Stuart,

Thank you for getting back to me so quickly.

How many decibels of isolation do you NEED, in order to be able to use the studio for what you WANT. It would be really sad to spend a lot of time, money and effort in fitting out your place, then find it is unusable most of the time because you can hear the neighbor's dog barking all the time, as well as his lawnmower, the traffic in the street, aircraft flying overhead, sirens from ambulance /police / fire in the distance, rain on the roof, wind.... you get the picture. Or even worse; the first time you use it, the cops come knocking on your door saying it is too loud, and you have to turn it off....

So your very first order of business is to define how much isolation you need, in decibels, to make your studio usable.

That number is what will define how you build your studio.

Based on what you were saying later in your response I'm guessing that around 120dBC (learning already!) isn't out of the question with a loud drummer, nor is around 110-115dbC when I'm mixing. So I suppose once I'm at that level I'll need some pretty significant reduction. I've got about 5m between the back wall of my studio and the back wall of my neighbours, with a fence and garden in between. Same with another that has a granny flat in the house behind my next door neighbour. There's at least 10m between the studio and the back of my house. These are the only neighbours that I'm really close to. By the time you get to the back of my neighbours either side, you're talking like 15-18m with fences and sheds in between. The noise should be significantly more quiet once it travels that distance. For most of my childhood I jammed in a normal room with an isolated and dead drum booth in a similar area, and while you could definitely hear the band outside, by the time we were up in the house we could only really hear a little kick and bass. We never had a complaint, but we also never played super late or super loud. I suppose around 50dbc isn't out of the question.

That will make a nice rumpus room, or TV room.. but perhaps not so much for a studio...

It's the only space I've got to work with and I've seen/heard great music and great mixes come out of even smaller spaces.

That's good news, but do be careful: if your brother and uncle have never done wiring or HVAC for a studio before, then they have a steep learning curve ahead of them: doing electrical and HVAC for a studio is not the same as doing it for a house, shop, office, school, etc....

So I've seen the star earthing on mains power thing in John's recording guide and my brother said he was fine with wiring it that way. I read more closely yesterday and discovered the part about the Earth stakes in the ground. I'll have to bring that up with him. We've got a seperate circuit for the lighting.

In terms of the Air Conditioning, all I could find on a quick google search was that HVAC does heating as well as cooling. Surely there's more to it than that and I'm missing something? As far as I know, my uncle sells fujitsu's and they all do hot/cold.

It would be nice if that were possible, but basically you won't have any choice: you WILL have to tear down some of what you built, in order to improve the isolation:: However, if you do that carefully, you can save the materials to re-use.

I get that. I wasn't expecting to have nothing to tear down. Obviously I want to minimise it where I can. I figure leaving some extra slack on all the wiring will allow us to just pull through the second leaf eventually, rather than a full rewire. I imagine we'll have to insulate around that too.

OK, so, what you are probably thinking of is calibration. Most studios and cinemas are calibrated at 86 dBC. That's the level they are tested at, to make sure that the response is flat at that level. But that is NOT the level that you must mix at! You mix at the level that you find comfortable, and that allows you to do the job well, without damaging your hearing. Most engineers tend to mix quieter than that: maybe around 75 to 80 dBC, then they push up the level to maybe 100 dBC or so briefly, every now and then, to "check the low end". And when the client comes in to listen to the mix, then probably play it at the blasting limit or their sound system, to impress the socks off the poor guy! But most of the time, it is more sedate.

However, you should probably do some testing with a decent sound level meter, to see what levels you normally mix at (average, and also peak), and design your room for that.

Will get a decibel meter today if I can. I assume it needs to be one that measures in dbC?

With a typical normal house type wall, you will get around 30 dB of isolation. That's it. So your 80 dB level inside will be about 50 dB outside. That's not quiet. And when you push it to 100 inside, it' going to be 70 outside. Hmmm...

Won't the sound be lower once it has to travel across my yard/through fences etc.?

but I have had good success on several studios with Sika brand FC-11 sealant.

sounds good! confirms what I thought re sealing every gap.

If it is fiberglass, then you want a density of around 30 kg/m3. If it is mineral wool, then it needs to be around 50 kg/m3.

This rings a bell. I think that's what we used.

There won't be much difference, since you are not decoupling your inner-leaf. It will be a bit quieter, yes, but nowhere near quiet enough for critical listening. Installing a drywall ceiling will reduce the highs frequencies form the rain mostly, but the lows will still get through.

I guess I won't be mixing in thunder storms then

If you did that now, you'd have to rip it out and throw it away when you re-do it with proper 2-leaf isolation later.

Also good to know about the putty packs. I won't bother for now!

The glass must be as thick as you as possibly get it, hopefully a single pane of laminated glass, and NOT a double-glazed unit. Also check that the seals are high quality when the door is closed, with no air gaps around the edges at any point.

Interesting... I would've thought double glazed would've been better.

Apart from the isolation, you also need to start working on the layout for your gear. Specifically, the correct location for your speakers and the mix position, plus the bass traps, cloud, and first reflection point treatment. That is very important. Room symmetry is critical, and so is the correct relationship between the parts of the room

These are the two possible mix positions I can see. Mix position 1 is probably the one I favour, mix pos 2 is probably more practical. In John's initial idea, he was going to suggest a sliding door and wall between the corner of the bathroom and the front wall to make a control room, leaving the other space as a live room. Until I can afford otherwise, it's probably going to have to just be a one room deal...

Based on what you were saying later in your response I'm guessing that around 120dBC (learning already!) isn't out of the question with a loud drummer, nor is around 110-115dbC when I'm mixing.

120 is certainly possible in the LR, but it would be very unusual to mix at 110. Most people mix at maybe 80 or so.

I've got about 5m between the back wall of my studio and the back wall of my neighbours, with a fence and garden in between.

Air loss over 5m is maybe 5 dB or so.... The fence and back wall don't do much to change that.

There's at least 10m between the studio and the back of my house.

So maybe 7 or 8 dB advantage there.

you're talking like 15-18m with fences and sheds in between.

That's good for maybe 10 or 12 dB reduction...

The noise should be significantly more quiet once it travels that distance.

Depends on a lot of factors. Inverse square law applies only for full-space, but since you are planted firmly on the ground, you are only in half-space. Buildings, trees, parked cars, and things can change that but figure maybe 3 or 4 dB with each distance doubling.

It's the only space I've got to work with and I've seen/heard great music and great mixes come out of even smaller spaces

The space itself is fine! I was referring to the isolation / treatment plan...

So I've seen the star earthing on mains power thing in John's recording guide and my brother said he was fine with wiring it that way. I read more closely yesterday and discovered the part about the Earth stakes in the ground. I'll have to bring that up with him. We've got a separate circuit for the lighting.

He'll also need to now about the "on single penetration" rule and the "everything surface mount" rule.... He cannot, under any circumstances, cut any holes in your walls to mount the outlets, switch boxes, or light fixtures. Everything is surface mount.

In terms of the Air Conditioning, all I could find on a quick google search was that HVAC does heating as well as cooling.

HVAC is a huge subject, and very commonly overlooked by first time studio builders. Yes, the "H" stands for Heat, and the "AC" stands for "Air Conditioning", but those are the simple parts, that are fairly easy to implement. It's the "V" you have to be careful of... "V" = "Ventilation".

Surely there's more to it than that and I'm missing something?

Yup! You are missing the "V". People have this bad habit: it is called "breathing". In order to isolate, a studio is sealed absolutely air-tight: no air an get in or out. As you can imagine, there's a slight conflict there! To breathe, we need fresh air to come in, and stale air to be removed. That's the "V" part. You have to do that without providing any path that sound can get through. You have to bring in enough air to keep people alive, and remove the same amount of stale air, and you have to do it at a high rate, but low velocity.... It gets complicated....

As far as I know, my uncle sells fujitsu's and they all do hot/cold.

I'm sure they do, but the do not ventilate! A mini-split system will do fine for cooling your room, and controlling the humidity, but it does not bring in fresh air, not does it take out stale air. All it does is recirculate the air already in the room, cooling it and dehumidifying it.

I figure leaving some extra slack on all the wiring will allow us to just pull through the second leaf eventually,

No, because that implies making a hole in the wall for each place where you do that! And you CANNOT have any holes in your walls... because in order to achieve good isolation, they have to be air-tight. Hermetic. Each leaf is a completely sealed "shell", because that's what you need in order to create the fully-decoupled 2-leaf MSM system that provides your isolation. Put a hole in it, and all your money is wasted: your isolation is trashed.

Will get a decibel meter today if I can. I assume it needs to be one that measures in dbC?

Right! It needs to have both "A" and "C" weighting scales, and it also needs to have both "Fast" and "Slow" integration options. It can have other features too, but it must have at least those.

Won't the sound be lower once it has to travel across my yard/through fences etc.?

Yes, but not by much. The fences basically do nothing useful: sound just goes over them. It's the distance that matters most. There's two things going on at once: one is the "inverse square" rule, where the sound is spreading out over a larger and larger area, but as I mentioned above, that applies to full-space, an you are in half-space. The other effect is air attenuation: just from traveling through the air itself, the sound loses some energy. But it's not very much at all over the distances we are talking about. Negligible. The only thing that really helps here is inverse square.

Interesting... I would've thought double glazed would've been better.

Double-glazed is OK for typical voice frequencies, office noise, house noises, street noise, etc. but not so much for full-spectrum music. It's sort of complicated, but any time you have two "leaves" of massive surface with an air gap between, you have a resonant system, and it has a natural resonant frequency, F0. At that frequency, it does not isolate at all: it transmits sound very well, from one side to the other, because both leaves are moving in perfect synchronization. At higher frequencies it starts to isolate, and above about 2 x F0, it isolates decently. A double-glazed window unit is exactly that! A tuned 2-leaf system. And because the air gap is very small and the glass is thin (low mass), the F0 frequency is very high, well into the bottom end of the spectrum. So it does not isolate the bottom end, but it does fine higher up. A single massive pane of laminated glass works much better, because it is has no tiny air gap inside.

Plus, if you start out with a double-glazed window in one leaf, then you add a second leaf, you now have THREE leaves, which is bad. A three-leaf system will ALWAYS have a higher resonant frequency than the equivalent two-leaf system, so by adding the third leaf you can potentially get WORSE isolation! Not intuitive, but very true. Three.leaf systems actually have two resonant frequencies, F+ and F-, and BOTH of them will be higher than the F0 of the two leaf system having the same total mass and thickness.

And a four-leaf system is even worse again. So two double-glazed units next to each other is pretty bad for the lows.... drums, bass, growling electric guitars, low end of the keyboard....

Mix position 1 is probably the one I favour,

Definitely! That's the only reasonable layout. Room symmetry is critical for mixing, so the left half of the room needs to be the mirror image of the right half., and that first layout accomplishes that fine. It also allows plenty of space at the rear of the room for the bass trapping. However, the doors at the front are potential issues....

In John's initial idea, he was going to suggest a sliding door and wall between the corner of the bathroom and the front wall to make a control room, leaving the other space as a live room.

Yup. I would do the same, or similar.

- Stuart -

Back again after an extended break. Still looking to move ahead with the studio build and I'm a bit concerned about the height of the ceiling.

The ceiling height is only 2410mm from concrete floor to the ceiling joists. I'm worried that won't be high enough to put in the second layer of ceiling for the full room-in-a -room isolation.

I'm worried that once I put in some kind of floor and a ceiling I'll be scraping my head on the roof (I'm 1850mm tall myself!)

Is all hope lost? Am I going to be able to get sufficient isolation from such a short room, or am I better off long term trying to get the height of the ceiling increased?

Is all hope lost? Am I going to be able to get sufficient isolation from such a short room, or am I better off long term trying to get the height of the ceiling increased?

Never!

The size of the room has nothing to do with the amount of isolation you can achieve. It is more detrimental to the acoustic response of the room.

You can talk to a structural engineer to see about re-working the rafters.

Greg