Which slat absorber design for this small room?

[CoreyM]

I need to finish this small room. Corners and cloud are done, just need some panels I can place around the room, they must look good. Only using this room to track vocals and acoustic guitar. Attached is the room and a sample room I like the look of. If anyone can point me at the right plans to build out the panels for this room I would be grateful. Also curious about opinions if a small room with this layout would be too live? Should the slats be spaced more? Thanks.

studioTwo_2.jpg

room.jpg

[Soundman2020]

Hi. Please read the forum rules for posting (click here). You seem to be missing a couple of things!

just need some panels I can place around the room, they must look good.

The primary purpose of acoustic treatment is to treat the room acoustics. Not to "look good". The treatment must be specifically designed and tuned to the room in question: you cannot just throw up any type of treatment in any room, just because you like the way it looks!

If anyone can point me at the right plans to build out the panels for this room I would be grateful.

You should probably start by buying the book "Master Handbook of Acoustics" by F. Alton Everest. That will teach you the basics of acoustic design, how to predict what treatment your room needs, how to design the treatment, and how to build it and install it, then how to test it to make sure it is working correctly.

Also curious about opinions if a small room with this layout would be too live?

Too live for what? And what do you mean by "too live"? Acoustics is all about science, math and measurement, combined with the art of music. What I call "too live" might be "too dead" for your music style, your needs, and your room. You need to set a target RT-60 time and a target frequency response profile, then design the room correctly to produce those.

Should the slats be spaced more?

A slot wall (what you show in the picture) is a tuned resonant device. It absorbs some frequencies while reflecting most others and also diffracting and diffusing yet others. Each of those is controlled by adjusting the parameters of the entire wall. This isn't about making it "more live" or "more absorbent" by adjusting the slat spacing. What it IS about, is tuning the slot wall to the range of frequencies that YOUR room needs to have treated, and NOT tuning it to the range that does NOT need treating. That's the challenge here: you can tune each of the slots to do a specific job with a high Q at one exact frequency, if you keep the percentage open area small enough, or you can tune the entire wall to be a single device with a low Q across a broad range of frequencies, if you make the percentage open area large enough. Or you could do both at once: tune one part of the wall to specific frequencies, and leave the rest tuned broad-band.

Your room is a reasonable size for tracking vocals and some instruments, but it certainly won't be "live" they way it is right now, since you treated it partly with OC705. That will kill the high frequencies quite well, but won't do much for the lows, so your room will likely sound a but dull, muddy and perhaps even boomy the way it is now. The rest of the rom is all drywall, so it is basically reflective across most of the spectrum. Adding slot walls in some places would help, but I would also be adding large bass traps in the corners, partly or mostly covered with thick plastic on the front face.

Corners and cloud are done,

How? They are not shown on your diagram. How are they built? What angles? Photos? Dimensions? Also, why do you need a cloud, if this is a tracking room? What is the purpose of the cloud?


- Stuart -

[CoreyM]

The primary purpose of acoustic treatment is to treat the room acoustics. Not to "look good".

I have $10K in Real Traps here. They work great, they look like crap in the room though. You can't book an ugly room. As I mentioned the solution needs to be attractive to sell hour, this is not up for debate in this case

You should probably start by buying the book "Master Handbook of Acoustics" by F. Alton Everest.

No, we have no time and just need to get the space done.

Too live for what?

As it mentions in my post I am using the room solely to track vocals and guitar. Most working engineers would define too live as enough presence of the space in the recording to affect it's ability to sit in their mixes.

OC705. That will kill the high frequencies quite well

Faced 705 doesn't "kill" high frequencies. But this is beyond the scope of my post. I just need plans on how to design the wall panels in the photo.

Thanks for the reply, I don't want to get into any side debates, we're just a group of artists pressed for time to complete a space our peers will want to use. We deeply appreciate any directly related advice, i.e. how to build out those panels and simply don't have scope here beyond that. Deepest gratitude.

[Soundman2020]

No, we have no time and just need to get the space done.

If you don't have time to do it yourself, then hire someone to do it for you! Send a PM to John, and ask him to quote for designing the treatment for your room. Or PM me if you can't get hold of John.

Most working engineers would define too live as enough presence of the space in the recording to affect it's ability to sit in their mixes.

Actually, most smart engineers who want a room treated for them, would define "live" in terms of frequency response and decay times.

Faced 705 doesn't "kill" high frequencies.

Well, the manufacturer seems to think that it does! And so do us folks who use it for that very purpose in the rooms we design for our high-end customers... The coefficient of absorption for faced OC-705 above 1 kHz ranges from about 0.4 to over 0.8 ... That's pretty darn good HF absorption. (If you don't believe me, check out page 26 of the technical specifications, published by the manufacturer.)

Thin 705 installed against the wall is also pretty lousy for low frequency absorption, as compared for example to 703 or 701. 705 is rarely a good choice as the primary treatment for a room: the density is too high, and therefore it doesn't do a great job of removing low-frequency energy from the room, which is, of course, the biggest problem in small rooms like yours.

But this is beyond the scope of my post.

So treating your room correctly is beyond the scope? I'm sorry you thought I was "debating". Rather, I was trying to tell you what is wrong with your room, and what needs to be done to fix it, since I assumed that was the reason you came here in the first place; to ask advice from people who know how to do what you want to do. I'm not sure how that could be "beyond the scope"...

I just need plans on how to design the wall panels in the photo.

And like I already told you, those are not "wall panels", they are "slot walls", and they need to be designed for EACH SPECIFIC ROOM! It's not a "one size fits all" device. What works well for one room will likely make another room sound bad. The design is based on an acoustic analysis of the room as it is right now (try REW for that), in order to identify the specific problems, and is also based on the desired characteristics, in terms of frequency response and decay times. You compare the data from the analysis against the data of what you want the room to sound like, then you design each part of the slot wall to treat a specific part of the spectrum, or if that isn't necessary, then you design it to treat a broad range of the spectrum. You tune each slot using the equation:

F= c / (2 * PI) * SQRT ( r / ((D * M * d) * (r + w)) )

Where:
c = the expected speed of sound in air, in your room (depends on altitude, temperature, humidity, etc).
r = slot width
d = slat thickness
w = slat width
D = depth of the sealed cavity behind the slats (rear face of slat, up to the face of the solid, massive, rigid backing).
M = mouth correction factor (usually around 1.2)

If the open area percentage of the entire slot wall is less than about 10%, then it acts mostly like an array of individually tuned Helmholtz resonator absorbers with high Q. If the open area percentage is higher than about 25%, the wall will act more like a broadband absorber, centered around an average frequency, with low Q (unless the slats are very wide, in which case they will reflect frequencies whose wavelength are small in comparison).

Each slot needs to be located close to the pressure mode in the room for the issue that it is designed to treat (slot walls are pressure devices, not velocity devices).

The cavity behind the slats must be sealed air-tight, and the surfaces that define it must be thick, rigid, hard and massive. If not, thy will vibrate, thus changing the tuning of the device.

Suitable insulation goes right behind the slats, and should be at least a couple of inches thick. 703 is a good choice, but not 705 (too dense). Also, the insulation CANNOT be faced: it must be plain. The foil on the face would prevent the air slug from moving in and out of the cavity, thus nullifying the effect completely. Only plain insulation can be used as the damping element in a slot wall.

Here's an example of how one forum member used this information successfully to tune his slot wall to deal with a specific issue: http://www.johnlsayers.com/phpBB2/viewt ... 74#p101974

Here's the predicted absorption graph for part of a slot wall that I designed for one of my customers recently, for three different gaps:

slotwall-graph-2-d.gif

Saying that you just "want plans" for building a slot wall is rather like saying you just "want plans" for playing a guitar... Nobody can give you either of those "plans", because there's no such thing. In both cases, getting results takes time, knowledge, understanding, learning, etc. So either you take the time to learn how to play the guitar, or you ask someone to play it for you. But if you do that, then it's probably not a good idea to then tell them that when they talk about first tuning the guitar before playing it, it's "beyond the scope" of what you thought you wanted. Telling us that figuring out what is wrong with your room so you can fix it is "beyond the scope", is like telling telling Carlos Santana that tuning his guitar before he plays is "beyond the scope of playing a guitar"...

If you don't want to be bothered with going to all that hassle of doing the necessary steps of analysis, calculations and design, then you won't get very far. You could throw up a generic slot wall (there are designs for that right here on the forum), tuned as generic broad-band treatment for typical average rooms, and hopefully you'd get generic typical average results, if you get lucky. Or you might not.

If you go that route, then good luck with your quest. It seems you probably will do that, based on your attitude in your last post, since it looks like you don't actually want any solid, sound, acoustic advice from people who know how to do it, and who design high-end studios for a living. So if that's the case, then we wont bother giving you any. For useless generic room treatment, just try carpet and egg crates. That seem to work well, according to YouTube....

On the other hand, if you do want to get this done right, then stick around, ask questions, learn from people who do this for a living, listen to the free advice you get, try things out, follow our advice, and get a great room as a result, which is what most forum members do.

Oh, and don't forget to check the forum rules that I mentioned in my first reply. You are still missing out on a couple of things there, and you likely won't see much response on your thread until you fix that. You just got lucky with my replies today, as it's a public holiday where I live, and I had some spare time on my hands. You probably won't get that lucky again if you don't follow the rules we have in place. They aren't that complicated...


- Stuart -

[CoreyM]

Not here to argue or hire John. I'll find something on the interwebs. Thanks for the replies, best.

Nobody can give you either of those "plans", because there's no such thing

I can absolutely give you those plans if you are serious. I've taught a few hundred people to play guitar, and counting. The system of playing guitar is very simple. Strong right hand is the key, with almost everything coming down to three things. Fingerpicking, picking, and hybrid picking, with each of those being broken down easily into similar, i.e. picking with be one of three things, one one string, across adjacent strings, or across non-adjacent strings. etc. Super simple. What I just gave you is a big chunk of what you need, a few accompanying exercises and you can make a strong intermediate out of yourself in 30-90 days depending on your knack. Without any books or debate. The plans are easy.

[Soundman2020]

There is an announcement at the top of the forum about what to do to assure getting as many responses as possible. The announcement leads to this post (click here). Actually, several people, who are experts on this forum, will most likely not reply if you don't do what is written in that post. Many others who are very helpful, will most likely not reply out of respect for the moderators' wishes.

If you can't even be bothered to follow the rules for this forum, and can't even see the glaring irony in your own post with advice about how to play a guitar as compared to the free advanced advice I gave you on how to build a slot wall, then there's not much point trying to help you.

If that's the case, then please do follow the advice you find on YouTube, but most of all, please do show the REW graphs from "before" and "after" you treat your room. We get a few people here every now and then, with a chip on their shoulder, who rave about how they can do things randomly without following acoustic principles or learning anything about it, and how they will come back in a couple of months to show us just what a wonderful job they did. But they never do... one can only guess about how "well" their rooms turned out, based on looks alone, not acoustics.

So if you choose to go that path, I challenge you to take actual acoustic measurements of your room using REW, both before you start treating it then again afterwards, and come back to post the results here.

See if you can get close to these:

Full Spectrum Frequency Response:

RMOUS-14-J-29-FR-20-20k.png

Full Spectrum Decay time:

RMOUS-14-J-29-RT30.png

Low frequency waterfall plot:

RMOUS-14-J-29-Waterfall-15-150.jpg

Low frequency spectrogram:

RMOUS-14-J-29-Spectrogram-15-280.png

The room itself:

RMOUS-14-J-29-Room.jpg

The original frequency response, before treatment:

RMOUS-14-J-29-FR-20-20k-BEFORE.png

The original decay time plot, before treatment:

RMOUS-14-J-29-RT30-BEFORE.png

If you can get your room even within distant shouting distance of those results, based on advice you get from watching YouTube videos, I'd be shocked, but I'd love to see it. You'd be the first one to ever do that!

Most of the differences you see in those graphs were accomplished by tuned devices, specifically designed to treat individual frequencies, or ranges of frequencies, or decay times issues, or diffusion issues. Those graphs are what engineers look for in an accurate room. Or at least, engineers worthy of the name.

Some of the devices were slot walls, carefully tuned to specific issues. Others were slot walls tuned broadband. There are also perf panel devices, membrane traps, bass traps, tuned diffusers, and plain old porous absorption. All of it carefully combined to get very precise, accurate, smooth response.

If you really do want what you say you want (a place that knowledgeable artists and engineers will want to rent, for good money), then that's what you should be shooting for. Studios are not built primary for how they look: they are built for how they sound. Once that is in place, then the looks can be fixed too, to get whatever vibe the owner wants. Acoustic treatment can be left blatantly on display, if that's the look the owner wants (such as the above room), or it can be blended with the room walls partially, or it can be totally hidden. That's up to what the owner decides for his room.

But regardless of the look he wants, the important issue is that the treatment must first and foremost be designed to make the room sound good. It makes no sense at all to choose a type of treatment that looks cool, then try to kludge it into the room forcibly, even when it makes no sense acoustically. That's a very shortsighted and rather silly approach to tuning a room. In your case, you want a slot wall because you like the way it looks, not because you have determined that you need one acoustically. That doesn't sound like a smart way of designing a room. If you happen to like the way that looks, then there are indeed ways of building a fake slot wall that has little effect on the acoustics, but that's not what you asked about. You wanted to adjust the slat gaps in case that would help to do something useful, without understanding the purpose of the device.

So you have a choice: Do you want to just have a room that looks nice but sounds like crap and is not even close to accurate or smooth? Or do you want to have one that first sounds great, is demonstrably accurate acoustically, and also looks good? The choice is yours. Either way it can look great, but you get to choose if it also sounds good or not.

If you want the first option, then by all means go to YouTube for help, and build whatever you think looks nice in the flashy videos you see there, but do not expect the room to be accurate acoustically, nor to make money from discerning artists and engineers.

If you want the second option, then stick around here, provide all the info we ask for in the forum rules (there's a reason for those: so we can HELP you), do the simple acoustic analysis I mentioned with REW so we can see what is wrong with the room and tell you how to fix it, then get the best of both worlds: a room that sounds good and looks good.


- Stuart -

[CoreyM]

with a chip on their shoulder, who rave about how they can do things

No idea what you are talking about. I found what I was seeking here: http://www.johnlsayers.com/HR/index1.htm

Got some built, they are perfect. Room solved. Big thanks John! Rock on lads.

[Soundman2020]

No idea what you are talking about.

Clearly!

Interesting to see that you still refuse to follow the rules for using the forum... Most people figure out how to do that after being told once. You've been told three times now (four, if you count this)... So no chip, eh?

I found what I was seeking here:

... which is exactly what I told you to do, back here:

"You could throw up a generic slot wall (there are designs for that right here on the forum), tuned as generic broad-band treatment for typical average rooms, and hopefully you'd get generic typical average results,"

So it seems you are happy with "generic typical average results"... sort of what I expected.

Got some built, they are perfect. Room solved.

Knowing what I now about how slot walls are built when done correctly, I'm finding it somewhat hard to believe that you managed to build several slot walls in a couple of hours, and purely by chance they solved all the problems with your room! It takes longer than that for the varnish to dry!

To prove your claim, maybe you could post photos of the finished room and slot walls, and also the REW graphs showing the acoustic outcome....

As we say around here: "Pics, or it didn't happen.".


- Stuart -

[CoreyM]

Interesting to see that you still refuse to follow the rules for using the forum... Most people figure out how to do that after being told once. You've been told three times now (four, if you count this

OK, so to be fair you don't seem to understand the phrase you are using. So to have a "chip on your shoulder" means, "to seem angry all the time because you think you have been treated unfairly or feel you are not as good as other people."

You seem to imagine these apply to me personally somehow not ever having met me on the basis of what's been posted here? You're intense. I would suggest a little too intense. I do thank you for your replies, in the end I found my final plans with some help from Rod Gervais at Gearslutz so all is well.

As for being stressed because the world isn't reading or following your rules, it's a syndrome some folks have. While we're all at dinner you are in the parking lot arguing about the way the lines were painted. To each their own my friend, I wish you a happy weekend.

[Soundman2020]

As for being stressed because the world isn't reading or following your rules, it's a syndrome some folks have

Why would I be stressed? I really don't care if you follow the rules or not! They are there for YOUR benefit, not mine... as you would already know if would knock that chip off your shoulder, and actually read the rules...

- Stuart -

(PS. You should probably look up the actual meaning of the phrase in a reputable dictionary, since your guess is woefully wrong. It has nothing to do with anger, nor with feeling inadequate...)