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-
