Garage Studio with Isolation

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afanacii
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Garage Studio with Isolation

Post by afanacii » Wed Dec 18, 2013 3:19 pm

First posting, so I'll do my best:

Converting ~17' x 17' garage into a "studio" with a sound isolation room inside of it. Basically, in one corner there will be a room within this room with 8' x 8' of interior space, with 8" thick cement (not concrete, if it makes a difference) walls. The entry would be a 32" solid wood door that opens out, which leads to another door that opens in, both backed with insulation (tempurpedic egg-crate or similar). One 24" x 36" window composed of three panes of 1/4" thick glass. Overall height inside = 7.5', capped with 2 layers of drywall, then 2x4s with insulation, then 2 more layers of drywall, with a air gap before the ceiling of the garage (bedroom above this room).

The intended purpose of this isolation room is for recording loud guitars/bass guitars, and vocals 1) without disturbing family members and 2) allowing me to monitor the track with the mix while playing it with relative accuracy. In some cases, only the amplifier and the mic would be in the room, with a custom jack plate allowing for the hook up through the wall. 3) is to maintain privacy when experimenting/recording with aggressive vocal techniques that I have not completely mastered :oops:

The rest of the garage would be an L-shaped space, with a few tables on casters allowing me to adjust position for finding a good monitoring position in such an odd space. There will also be some bicycles hanging on the walls, a hot water heater, a few shelves of tools, books, etc in here. Some isolation and treatment measures will happen here, but I have no illusions of "finished" work coming out of this joint, unless by finished I mean "unfinished" which may sometimes be the case.

My question is thus: Based on evidence that someone before me in my family tree got beaten mercilessly with the stupid stick, what horrors await me as a final result of this project. An extra set of brains are always useful. More specifically, how might I treat the isolation room to strike some balance between keeping reflections down while keeping the sound "alive". Perfectly willing to post images of the rough design, if anyone is interested, as soon as I figure out how to post images here.

Thanks!

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ott0bot
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Post by ott0bot » Wed Dec 18, 2013 4:18 pm

seems like this would work for an amplifier isolation room & multiuse space....

...except I see one major issue:

I think an 8 x 8 room with have some issues with early reflections and some frequency resonance due to room modes. I would do a rectangular room to avoid some of those issues. You are also missing one other crucial dimension: height. As 8 ft is a standard ceiling height. you'd end up with a cube of relection, that would probably made a less-than ideal recording space.

here is a handy calculator for room modes, that can help you find what frequencies you'll have to contend with at a set length, width, and height. I'm planning a garage build out soon, and knowing where you'll have issues will help you plan out the best way to build the space.
http://www.bobgolds.com/Mode/RoomModes.htm

the Rod Gervais book is super helpful too.
http://www.amazon.com/gp/aw/d/143545717X

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JWL
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Post by JWL » Thu Dec 19, 2013 1:56 pm

I do see a few issues with what you have written. First thing to understand is that isolation is not easy to achieve, and success results from a lot of little things all done correctly.

I agree with Ottobot, go get Rod's book right away. Specifically look at his window designs (and why 3 window panes are a bad idea), as well as his discussion on 2-leaf, mass-air-mass systems to maximize isolation.

Concrete is great because there is a lot of mass for a relatively low budget, but it may not be the best solution.

Also I agree with Ottobot that an 8x8x7.5 space is asking for trouble acoustically, in terms of getting good sounds out of the room. Specifically, your low end will have some serious problems, the most severe of which will probably be near 140-150Hz (as well as its multiples). All 3 room modes will be nearly the same, so the solution there is to use different room dimensions.

afanacii
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Post by afanacii » Thu Dec 19, 2013 2:37 pm

Thanks both y'all. The link to the room modes calculator is cool beyond words, and makes me feel like I really need to read a book (per advice). Playing with it shows me how little tweaks make a big difference, but I'm a little confused by the results: After some fiddling, 6.9' x 8.3' x 7.1' tall (yes, using decimal feet) I was able to achieve a nice curve on the chart on the bottom of the page, which is conveniently labeled "Good". To the left, however, is a list of Frequencies, modes, etc., each weighted based on the inputs and color coded ranging from green to red, also pretty intuitive, but the relationship between these colors and the chart below doesn't appear particularly strong. Sometimes I get more Christmasy colors with a smoother curve and almost solid green with an ugly dip in the curve. Instincts tell me to pick dimensions that yield a solid middle ground between these two metrics.

I promise I will read up a bit before building, but one of my curiosities now regards angles. I've heard seemingly educated people disagree on this: Is there any benefit to building, or shimming, the walls out a bit so as to make the surfaces non-parallel? Don't have enough room for a really odd shape, just thinking about making the walls and ceiling 1-2" off square. Then of course, it would certainly affect the room modes calculation with no way to input the changes. Is adding angles just asking for trouble?

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JWL
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Post by JWL » Sat Dec 21, 2013 11:21 pm

Not really. The main thing angled walls do is a) eliminate flutter echo, and b) aim reflections in a different direction.

Flutter echo is very easy to treat with absorption or diffusion. Aiming reflections can be good or can be bad, it depends on the details and on what happens to the sound once it hits the next surface. For instance, splaying walls in a control room will tend to aim reflections toward the rear of the room (and away from the listener's head, which is good). But then treating the rear wall becomes that much more important.

In general, non-parallel walls means that the room is not as large, cubic feet wise, as it would be with the parallel walls. I personally would never make a small room even smaller just to have non parallel walls.

Simple rectangular rooms also have the benefit of being very easy to predict, and easy to treat acoustically (provided you plan ahead for the treatment, ie, keep doors away from corners where you want to put bass traps and from reflection points where you want to put absorbers).

If you know what you are doing, and have enough volume to splay walls, then great. If not, generally you are best off sticking with a rectangular room with a decent ratio, and of course good treatment. imho.

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