Turning a wooden shed into a mixing room

[bubblypatrick]

Hi everyone,

The house I just moved to has a woodshed in the backyard built by the previous owners. I was hoping to turn it into a mixing space, and I would love to get some feedback or advice on my plans. I started freelance engineering full time just over a year ago, and have interned and assisted three years before that. I would love to make a room where I can get mixes close enough to good. That way, when it comes time to bring it to a commercial studio for final tweaks, I would be saving time.

I've never built a studio before, I spent awhile reading everything I could find on this forum about acoustics relevant to this situation. Sorry in advance if I mention any cardinal sins.

The shed is 12'x8'x8', and the roof is angled. The roof angles twice before reaching its ridge (see pictures.) The first angle occurs at 4 feet high and is angled 65°, the second is at 6'3" and is 115°. This is on both sides and meets at the top ridge. The shed is constructed of 2x4 frames and wood siding. You can easily see the framing from the inside, there's no insulation in place. So I think, "hey I think that's a double leaf wall in the making, I can make use of these air cavities to more evenly trap the frequency spectrum." I'm still not totally sure of the floor build, but it appears to be thick plywood sitting on top of a frame, on top of some concrete fittings. It has a glass screen door that I'm going to replace with a normal door. There is also a nice shelf built in, right next to the entrance. There's a sauna built 25 feet away that's providing me with a 60 Amp circuit

The build seems solid and hasn't had any problem supporting all of my gear. I only have one set of neighbors in the immediate area, and I've been listening to music at around 85dB with no complaints. I'd still like to contain some noise, even taking off 20 dB's to the outside world would be great. I'm currently not using a sub, but I'm saving up to buy Neumann KH310s, that will be moving a lot more sub frequencies. That's all the background info I can think of.

Here's my plan so far:
-Add a simple layer of some kind of hardwood flooring
-Place acoustic treatment on walls and ceilings
-I'm hoping to hang my lighter, 4'x1'x1" and 1'x1'x1" acoustic treatment on the angled braces so as to create as many different dimensions of cavities as possible. (see picture, I would cover the holes entirely, but I ran out of hands)
-I want to place my large 8'x4'x4" panels against the side walls, again creating pockets. (also in pictures)
-Hang a bit of acoustic treatment as a cloud to help add diffusion
-Replace Door
-Still not sure what to do with the front wall (the one directly behind the speakers)

I have a couple different kinds of acoustic panels at my disposal. I think the variety of panels, panel material, and the angles of the braces could help create a wide variety of air pockets to kill tons of different frequencies.
I have:
-Primacoustics London 12 pack Basically 1" and 2" thick treatment
-4 gobos from a local studio that have owens corning 703 measuring 8'x4'x4" (I had a hard time fitting more than 2 in the shed)
-A 7'x4' area rug

My questions are:
-Is this even a good idea? I realize acoustics is a difficult subject, and this is just my guess as to what would work well.
-If not, what do you recommend?
-What do you recommend for the front wall? I'm open to any and all suggestions. I definitely don't want to leave it exposed, and want to kill all first reflections if possible.
-Is there any specific type of hardwood you would recommend?

My budget is currently $1000, but could go higher.

Thanks!!!

[Soundman2020]

I'm REALLY sorry I didn't see this back when you posted it! But better late than never, I hope...

The shed is 12'x8'x8'

That's a really small space! Good acoustics needs rather more than that: There's a document called ITU BS.1116-3 that lays out the ideal specs for control rooms, and among those is the recommendation for at least 20m2 floor area, which works out to about 215 ft2. At 96 ft, you are less than half of that. That doesn't mean the place is unusable: just that you won't be able to get great acoustics. But it is still possible to get something, even though it can't be world-class.

The roof angles twice before reaching its ridge (see pictures.)

Technically, that's a "gambrel" roof, often seen on barns and similar buildings. The advantage in your case is that it means the room does not have a square section, as suggested by the "12x8x8" dimensions. One of those "8's" is not really 8 at all; only at the peak. But from there it varies greatly. This is actually a good thing, because you never want to have two dimensions the same in a studio... or two dimensions that are directly related, mathematically, such as 8 and 12 for example...

So I think, "hey I think that's a double leaf wall in the making, I can make use of these air cavities to more evenly trap the frequency spectrum."

Not really. That's not how two-leaf walls work. They don't "trap the frequency spectrum" at all, in fact, and certainly not "evenly". What they do is to attenuate sound trying to get out (or in) in several different ways at once, and to several different levels for different parts of the spectrum. The hardest part to attenuate is low frequencies, and the easiest is very high frequencies. In the middle, it's complicated...

OK, so you have an outer-leaf, and now you need to add an inner leaf, but it needs to be decoupled from the outer. You don't have enough space to do a proper fully-decoupled wall, so your best bet is to put RSIC clips with hat channel on the interior faces of the studs and joists, then screw drywall onto that (with insulation in the cavity). That's your best option in a tight budget and with a very, very small room. With a bit of luck, it should get you around 40 dB of isolation, assuming that you seal both leaves airtight, and that you have suitable doors, windows, HVAC system and electrical system.

It has a glass screen door that I'm going to replace with a normal door.

A SOLID door, not a normal door, which is hollow. Hollow-core doors are no use for studios: use on solid core.

I'd still like to contain some noise, even taking off 20 dB's to the outside world would be great.

You are likely getting around 20 dB of isolation at present, and doing the above would probably get you those extra 20.

but I'm saving up to buy Neumann KH310s

Nice! But you will have to set up your speakers properly! Not the way you have them now...

-Place acoustic treatment on walls and ceilings

Yes, but only after you complete your isolation! Isolation and treatment are two entirely different things, and are accomplished in totally different manners. Not related. Many people think that putting insulation or foam on the walls will stopd sound getting out: Nope! It doesn't. That's treatment, not isolation. First you need to isolate, then you need to treat.

-I'm hoping to hang my lighter, 4'x1'x1" and 1'x1'x1" acoustic treatment on the angled braces so as to create as many different dimensions of cavities as possible. (see picture, I would cover the holes entirely, but I ran out of hands)
-I want to place my large 8'x4'x4" panels against the side walls, again creating pockets. (also in pictures)
-Hang a bit of acoustic treatment as a cloud to help add diffusion

Well, actually, no. That's not how treatment works, either.
Firstly, that's a VERY small room, so it will need a ton of bass trapping. The very best place for that, is in the room corners. The very best method for that, is with "superchunk" style traps in the corners, and second best is with large, thick, insulation panels placed diagonally across the corner.

-Still not sure what to do with the front wall (the one directly behind the speakers)

Superchunk bass traps in the corners, with some strips of plastic across to prevent sucking out too much of the highs, and absorption in the center, between the bass taps, at roughly the height of the speakers, plus about 12" up and down.

I have a couple different kinds of acoustic panels at my disposal. I think the variety of panels, panel material, and the angles of the braces could help create a wide variety of air pockets to kill tons of different frequencies.

Ummmm... Nope! You do NOT want to "kill tons of different frequencies"!!!! Definitely not. Yo only want to kill those that need killing, which will be pretty much all in the low end. Your highs will get killed anyway due to the huge amount of bass trapping, and you'll need to do something to PREVENT that from happening, such as like I mentioned above: with broad strips of plastic (6 mil) across parts of your bass traps. You will have to tune that carefully, to make sure that you are reflecting the right frequency range, and to the right extent. There are equations for calculating that.

-A 7'x4' area rug

Forget that. Carpets and room acoustics do not mix. Carpets do the exact opposite of what you need in a small room.

-Is this even a good idea?

It's a VERY small room, so it will never be Abbey Road. But it can be improved, and hopefully improved enough for your needs.

- Stuart -

[bubblypatrick]

Thanks for responding! I was very excited to see what you had to say.

That's a really small space

I wish it were bigger but it's what I've got to work with for the next year until I move to a space with a larger option. Hopefully I can do something good enough in the mean time.

Thanks for pointing out the difference between isolation and treatment. As I understand it: Isolation = volume control (among other things), treatment = frequency control. Is that right? I haven't received any complaints about volume, even when i crank my monitors to 95db to check for how the impact of my mixes feel. I'm pretty far away from the next house over, and it's occupied by a veteran with bad hearing I've asked him about the volume and he said he hasn't noticed anything coming from my shed. If my assumption that isolation is volume control is correct, can I just bypass that and start with the treatment?

SOLID door, not a normal door, which is hollow. Hollow-core doors are no use for studios: use on solid core.

Sounds good, I will get a solid door. Sounds like this is an isolation thing?

Carpets and room acoustics do not mix

I'll take that out as well.

Firstly, that's a VERY small room, so it will need a ton of bass trapping. The very best place for that, is in the room corners. The very best method for that, is with "superchunk" style traps in the corners, and second best is with large, thick, insulation panels placed diagonally across the corner.

Is the best way to do this to take a sine sweep room test and acquire superchunk traps that are at the room modes? If I need to do isolation then it seems to make sense to do the room mode test after isolation is in place. Is this correct?

In the event I don't need to do isolation, should I clear out the room except for the speakers and a microphone and take a test (making sure the speakers are at the best listening position mathematically) then start constructing superchunks with plastic strips?

Thank you Stuart!

[Soundman2020]

As I understand it: Isolation = volume control (among other things), treatment = frequency control. Is that right?

More or less, yes, but treatment is rather more that just frequency control. More on that later.

If my assumption that isolation is volume control is correct, can I just bypass that and start with the treatment?

Probably, yes. BUt with caveats.... Isolation works in both directions, going out as well as coming in. You don't see to have a problem with sound going out, but what about sound coming the other way? Rain, wind, hail, thunder, aircraft flying over, sirens, traffic, radios nearby, people talking, doors slamming, dogs barking, lawnmowers, etc. If you need to concentrate closely on your mixes, especially on the quite parts, then all of the above might be distracting or even totally prevent you from doing a mix for hours at a time. It's worth thinking about that. Professional studios usually specify how quiet it has to be inside the studio using something called the NR curve, or the NC curve. You can google that if you think it might be applicable. Most studios specify something like NR-15, or maybe a bit less for a home studio, perhaps NR-20. It might not be applicable to you, but then again, it might!

Sounds good, I will get a solid door. Sounds like this is an isolation thing?

Mostly, yet, but it also has some bearing on treatment. Hollow doors can resonate, since they are hollow. The tones they create and/or absorb can potentially mess with your room response.

Is the best way to do this to take a sine sweep room test and acquire superchunk traps that are at the room modes?

The best way is to run a full acoustic analysis of your room, using software called REW. It's free, and you can download it from here: http://www.roomeqwizard.com/ ANd you can find the instructions on how to use it right here on the forum: http://www.johnlsayers.com/phpBB2/viewt ... =3&t=21122

That will reveal all of the ugliness in the room, in great detail, which you can then use to decide on what treatment you will need, and where to put it.

Yes, superchunks for the room modes is a good place to start, but that just deals with room modes, and some bass buildup as well. But that's just a part of treatment. As I mentioned, treatment is not just about getting frequency response under control. That's one part, but not all of it by any means. Much more important is getting time-domain issues under control: Resonance, reverberance, flutter echo, and suchlike are major problems in most rooms, since they "stretch out" some notes greatly while not affecting other notes at all. In addition, there's also phase control to worry about: Your room will likely have issues where it causes phase cancellation of some frequencies at varying points in the room, and other issues that cause things like comb filtering, edge diffraction, and other nasties. There's also the issue of reflections: You do not want to ave any early reflections arriving at the mix position within a short period of time after the direct sound arrives. This is a "psycho-acoustic" issue, that's related to how humans perceive sound, not to how the sound actually is. Our ears and brains use very subtle clues in the differences in level, timing, phase, and frequency between the way sound arrives at both of our ears, to determine the perceived directionality and frequency response. If a reflection arrives within less tan 20 ms of the direct sound (known as the "Hass Time"), then our brains don't have enough time to process that difference properly, and instead we get the impression that the sound came from a different direction than where it really came, and had a different frequency spectrum from what it really had. A microphone does not "see" this issue, because it reacts basically instantly, but our ears and brains don't, and that messes up our perception. So you also need to prevent early reflections from getting to the mix position within 20 ms of the direct sound, and then also ensure that the late reflections (arriving after about 30 ms) are at a much lower level (about 20 dB lower, ideally), and also diffuse.

Treatment is about dealing with all of those, not just plain old frequency response. That's just a small part of treatment.

If I need to do isolation then it seems to make sense to do the room mode test after isolation is in place. Is this correct?

Yes, that would be better. But you could do an initial test before you isolate, with just the plain empty room, then do follow-up tests at each stage of isolation/treatment, to see how things are changing, what is working, what isn't working, what needs more attention, what went too far, what had other consequences (side effects), etc. The more info you have, the better you can understand your room, and the better you can treat it.

In the event I don't need to do isolation, should I clear out the room except for the speakers and a microphone and take a test (making sure the speakers are at the best listening position mathematically) then start constructing superchunks with plastic strips?

Yep! Use REW, post upload the results to a file sharing service (eg, Dropbox), and post the link here.


- Stuart -