Acoustic Treatment Advice

[mossimo654]

Advice For Acoustic Treatment

Here are pics and diagrams: https://imgur.com/a/oSGEVAX

Hi all,

So first off I know my request fits a cliche of “can your expertise help with my completely not ideal situation please.” If that annoys you, I don’t blame you and feel free to stop reading here! I know I’m a dime a dozen.

However if you’re interested in helping out someone to get the most optimal solution out of suboptimal situation and is tired of giving up on this because of it I could really use your help! I’ve been meaning to treat my room for years but always get overwhelmed by how technical and often contradictory things I read in various places is.

The room is 13x11.3 (I know) and I share it as an office with my partner. She needs a wall for her work desk as well as a blank wall for recording auditions (fortunately we have a shared desire to acoustically treat the space). She has conceded that I could put an acoustic blanket (are these even worth it?) on the blank wall she uses for auditions.

For me: is the best place to put my desk and monitors (HS8s) on the side with the window? The window has a shallow well, does that make a difference? Or should I put my desk somewhere else? If I do put it on the side with the windows, should I place my monitors equidistant on the wall which means they go right to the edge of the window well? If I put my desk there it is a third the length of the wall.

Additionally, I am going to put up bass traps on all the corners. I am also getting rockwool acoustic panels, where would be the most optimal place to put those (I know this info exists online but it doesn’t for when you have to negotiate the space with a partner lol)?

Anything else you’d recommend for the most optimal solution to this situation?

What would the best walls for my partner to use?

THANK YOU for taking the time to read this

[Lophophora]

Hi,

I think that in your case, the first thing is to understand that if you can't change rooms or even move your listening position inside the room, then you have to considerably lower your expectations because the first and most influential parameter is the size/shape/materials of the room and the second one is the position of the source (speakers) and listening point.

Acoustic treatment (done well) can always improve the acoustics, but if you start with a small room and a non ideal position you will never get good acoustics, no matter how much treatment you throw in there.

That being said, the one thing you should focus on is the low end. Smaller rooms have more room mode overlap and therefore more low end dips and bumps. You will find a plethora of "acoustic foam" products, stay away from these as in the vast majority of cases their thickness and the nature of the material doesn't allow any significant absorption in the low end. They do work in the highs and sometimes in the mids, but what you'll end up with is a false impression of improvement (because the room will sound less reverberant when you clap your hands for instance), and still the exact same amount of issues where it really matters: the low end.

A proper acoustic treatment in your room would mean emptying the room entirely, taking measurements with various source positions, pick the one that allows to have the least low-end issues at the listening position (the "low-end sweet spot") then create a reflection-free zone (RFZ), and focus on as much low-end absorption as you can fit in the room. Keeping in mind that with porous absorption, anything thinner than 20cm won't do much under 100Hz. You can significantly improve the performance of a porous absorber by leaving an air gap behind it (no larger than the thickness of the absorber). Other methods are more efficient (membrane traps, Helmholtz resonators...) but more costly, harder to implement and quite inconvenient in a small room.

To keep things simple, in your case I would focus on these 3 things:

1. As many bass traps as you can fit in the corners (real bass traps, not foamy things)
2. Create an RFZ = porous absorption at the primary reflection spots (usually above and on the sides of your listening position)
3. Use a good set of headphones! You'll still have some accidents in the frequency response in the low end, so you won't be able to trust your monitors entirely.

Hope this helps.

[RichardT]

It’s usual to have the speakers firing down the long axis of the room, all other things being equal.

A downside of having the desk by the windows is that the monitor will be competing with the natural light. Another is that you can’t put any treatment behind the speakers. Can you use the other short wall? If so, that we be an option to consider. But that’s not ideal either because of the asymmetry you will be introducing.

Lophophora’s advice on how to go about it is good. I think in a difficult room like this, it is important to test out which is the best position.

Don’t use foam! Even at reflection points, rockwool or an equivalent is much better.

Broadband trapping doesn’t need to be limited to corners and reflection points. The more the merrier, and thicker is better than thinner. I’ve used GIK monster traps which are about 170mm thick.

If using REW is too daunting (it was for me) you can still get very good results by ear and using simpler tools The differences are very clear when you start installing treatment, and move it around. Experimenting with positioning of trapping is quite important. Don’t stick with your first attempt at arranging it!

I supplemented listening by using Sonarworks room correction software, which will give you a good understanding of frequency hotspots in the room, and you can simply use a test tone tool in your DAW to listen to resonances.

If, after installing your broadband trapping you still have a significant resonances in the low frequencies (I expect you will) it is possible to use tuned traps to deal with those, but that should definitely be a later step, and broadband trapping should be your first port of call. You may not have room for that anyway, as Lophophora says.

[Sam Spoons]

Hi mossimo654 and welcome to the forums.

My room is quite close in size to yours (13' x 13') and my expectations were similar, I achieved, and probably exceeded my expectations for some effort and a modest amount of cash.

First, a couple of questions, will you be recording live instruments or will it be entirely electronics or samples?. Assuming the latter (or the occasional acoustic guitar which can be dealt with using the old duvet trick) then super chunks bass traps in the two corners next to the window and four panels at the side, rear and ceiling mirror points* will get you 70% of the way there. WRT the window, Hugh had some transparent/translucent panels he used which he rated or a venetian type blind will work as a rudementary diffuser over the window. Daylight is nice to have on a small studio so while you could make a Rockwool panel to fill the window void you might prefer not to block the light/view.

Second question, I'm assuming your wife is recording video for auditions, is this head and shoulders as a news reader might present or full length (think dancer) and does it need simultaneous audio (I'm assuming it does, can't think of a situation where it wouldn't) so you'll need to work out a way of achieving some visually attractive treatment around the video position (which would double as an acoustic instrument recording space), a panel on the ceiling above the talent and a sound blanket type heavy drape in an attractive colour/pattern is probably the pragmatic option.

I would put your desk where you suggest, in front of the window with everything equally spaced from the side walls, her desk, I'd place on the back wall with a panel over and the video/audition space could go against either side wall roughly 1/3rd from the back.

edit :- another thought, you would benefit from a panel opposite the video wall and what mic do you plan to use recording your wife's auditions?

edit 2 :- Personally I wouldn't bother with REW or whatever, it'll probably just depress you ( and it's very difficult to interpret the results in a useful way in a small room), you'll hear the improvements the first time you speak or listen to audio in the newly treated room. FWIW I have about 20% coverage of the area above the dado in my room which I'm planning to increase to about 30% soon by adding another 6 panels placed in those big white spaces in the pic below.

* https://www.soundonsound.com/glossary

[mossimo654]

Thank you so much for the detailed and thoughtful reply! First off you’re right, I’m only likely recording acoustic guitar, so I guess I gotta look up the duvet trick!

Translucent panels are a great idea (the wife definitely doesn’t want to get rid of daylight .

Her auditions run the gamut, but it can definitely include full body. By sound drape, you’re referring to the wall of that audition space right? Any recs on what kind or what to look for on that?

In terms of recording her auditions she’s been using just an iPhone… when I say we have a mutual interest in treating the space I mean I’ve convinced her we have a mutual interest haha. Her audio doesn’t have to be perfect.

I however usually use an AT4060 if I’m using a condenser.

Why do you think I’d benefit from a panel opposite the video wall in particular?

And THANK YOU for saying that about REW, that’s been exactly what I’ve been thinking .

[mossimo654]

It’s usual to have the speakers firing down the long axis of the room, all other things being equal.

A downside of having the desk by the windows is that the monitor will be competing with the natural light. Another is that you can’t put any treatment behind the speakers. Can you use the other short wall? If so, that we be an option to consider. But that’s not ideal either because of the asymmetry you will be introducing.

Lophophora’s advice on how to go about it is good. I think in a difficult room like this, it is important to test out which is the best position.

Don’t use foam! Even at reflection points, rockwool or an equivalent is much better.

Broadband trapping doesn’t need to be limited to corners and reflection points. The more the merrier, and thicker is better than thinner. I’ve used GIK monster traps which are about 170mm thick.

If using REW is too daunting (it was for me) you can still get very good results by ear and using simpler tools The differences are very clear when you start installing treatment, and move it around. Experimenting with positioning of trapping is quite important. Don’t stick with your first attempt at arranging it!

I supplemented listening by using Sonarworks room correction software, which will give you a good understanding of frequency hotspots in the room, and you can simply use a test tone tool in your DAW to listen to resonances.

If, after installing your broadband trapping you still have a significant resonances in the low frequencies (I expect you will) it is possible to use tuned traps to deal with those, but that should definitely be a later step, and broadband trapping should be your first port of call. You may not have room for that anyway, as Lophophora says.

Thank you! I definitely won’t be using foam, I plan on building corner traps out of rockwool.

I was wondering: in terms of placement by the window, I can put treatment on the walls right next to the window (there’s about 30” on either side). Additionally, for natural light you’re talking about my computer screens right? Or does that have to do with my studio monitors somehow?

[philthy9fifty]

After years of research, I think a lot of experienced musicians with their own studio setups will agree that your going to get the best results with a mix of different acoustic treatment methods. A lot of old books on book shelves are great for absorbing sound.. Acoustic treatment panels are one of the best and are superior to foam. I recommend watching some YouTube videos and building your own panels. I personally DO have foam covering the walls in my studio, but it's high density foam that is flame resistant. A lot of foam isnt and will thus make your studio a death trap. Hope that helps a bit.

[Sam Spoons]

The 'duvet trick' simply refers to hanging a couple of duvets over boom mic stands strategically placed to act as Gobos* or moveable panels. Works well for occasional sessions.

I have no experience on 'sound blankets' but they do get mentioned on here occasionally, basically though any heavy fabric drape will help reduce reflections from the, in camera, back wall, the panel opposite serves a similar purpose as that will be a 'mirror point' WRT your wife's position and the mic used to record her voice (I'd guess you could use a light drape behind her hiding another Rockwool panel at head hight rather than a heavy 'sound blanket/drape' which I think would be equally effective).

The window is providing natural light and will act as a rudimentary bass trap but will reflect high frequencies back into the room. A venetian blind will, to a modest extent, act as a diffuser at those higher frequencies but allow you to easily let light in when you desire. It's a pragmatic solution which will help a little but from an acoustic perspective a Rockwool panel will probably work better.

Here is a link to Hugh's Studio SoS https://www.soundonsound.com/techniques ... sound-good

* again, https://www.soundonsound.com/glossary

[Dynamic Mike]

A really handy way of using duvets in a small space is to attach them to an adjustable clothes rail such as https://tinyurl.com/2p876dmr from Argos. You can secure the duvet with a couple of bag clips or even clothes pegs. Best of all it they just wheel out of the way & can go up against a wall when you don't need them. Worth considering in a shared space & you can even treat the window space when you're recording.

Way cheaper, more convenient & actually look better than mic stands. Plenty of other places sell similar & some are better made but Argos seem the cheapest & do the job perfectly well.

[Lophophora]

Hey philthy9fifty,

I hope you won't mind me bringing up a different perspective on this.

After years of research, I think a lot of experienced musicians with their own studio setups will agree that your going to get the best results with a mix of different acoustic treatment methods.

When it comes to acoustics I would personally recommend to seek advice with acoustics engineers, not musicians. While some of them might know what they are talking about, a lot of them just rely on the copious amount of misinformation that can be found on internet.

A lot of old books on book shelves are great for absorbing sound..

Actually no, they aren't. Sound pressure is absorbed by porous materials (lots of small air pockets). Materials that are hard and slick like walls, doors, windows, desks, shelves and books primarily reflect sound waves. I am assuming you are thinking about diffusion, but unless your books and shelves have a really weird and unusual shape that follows mathematical patterns, they won't break up the reflections in an significantly beneficial way.

If you are DIYing your way into room treatment, diffraction is a lot harder to understand and implement than absorption. Piling up books on a shelf in hopes that it will make a good diffuser just doesn't work. Books will absorb little and diffuse a bit, but in a very uneven way that will most likely end up creating more imbalance than helping with the frequency response at the listening point, unlike a good diffusor that will scatter reflections evenly in all directions. And just like in absorption, the depth of of the diffusers determine their ability (or lack thereof) to handle the low end. Books are far from being deep enough to have any kind of control over the low end.

Also, things like blankets and duvets, as mentioned above, will absorb the high end and some of the mids, but never the low end. Keep in mind that in small rooms, you almost always have much larger issues in the low end than in the rest of the spectrum.