John Sayers' Recording Studio Design Forum Archive

Hi!

I'm planning to use a small rectangular area that i have in my house to record me and my band. Actually, is an open roof, so, i have limitations in the sides, but the height can be any (there's no roof yet...).

I want to have a recording and a control room. Two rooms. Will record drums, guitars and voice. Neighbors are a problem, so i need a good isolation. The room is in the 2nd floor. The entrance door have to be at the right red wall and cant be in any other.

I'm a bit confused about what approach i have to use to determine the dimensions of the 2 room inside. Are the "Golden Ratios" (like 1 - 1.14 - 1.39)? Or that 3 or 4 charts that i have, and each one says me one different thing...

Well, i don't know how to determine the sizes, to start the project.

Room sizes (in meters and in feets):

W: 2,92m (9,58 feet)
L: 7,03m (23,06 feet)
H: Can be anything

Dimensions above are without any isolation (i think 10cm of isolation at each wall will be good...). These existing walls are 15cm brick/concrete.

Any idea about the best way can i put these 2 rooms inside this?



Thanks and sorry for my bad english write!

Hi friends! Only to encourage you... I think first Autocad image is vary poor...



Only to remeber: I know the steps, after the project starts (teartment, isolation, etc). My problem is to decide what dimensions to use, to fit a recording (live) and a control room inside this. The entrance door have to be in the red wall...

According to my "modes" charts, there are some dimensions. But if i go to the "golden ratios", are a bit different. And io have other chart only for "small rooms", that are a 3rd opinion. SO i confused on what dimensions, to finally starts the constuction...

Thanks any help.

whoa... with a room that is 7030 meters x 2920 meters, you may want to consider building more than two rooms

ok, all jokes aside... i am definitely nowhere near as knowledgable as some of the experts on here, but as far as the ratios go, there are three numbers in those "preferred" ratios. so you will need to establish a height.. ive always thought that the height would be the "1" in the ratio, but maybe in your situation, the height could be the 1.39, assuming you are using the 1 : 1.14 : 1.39 that you mentioned

so your room could be
1= 292meters
1.14= 332.88meters
1.39= 405.88meters

however, that is just the outside wall dimensions, you are going to have to figure out what type of walls you are going to build, then thickness of the walls, and then that will give you the new size of your space.

like i said, i dont know if you are allowed to rotate the room on its side like that, but it seems like it would make sense (at least to my novice brain) and then you could utilize all that extra ceiling height for bass trapping. (at least that is what i plan to do in my design)

hopefully someone who is more knowledgable than myself will be able to confirm or correct my attempt at help..

beau

No problem with rotating the room, Beau: Sound doesn't care which way is "up" and which way is "left", so the overall modal response of the room will be the same. You just need to remember which way is which when you use the equations. However, you didn't really turn the room on it's side like that: you turned it on end! Your longest axis is now vertical, but it's usually a good idea to have your speakers firing along the longest axis of the room. So although the modal response will be the same, there are practical reasons why you might want to set that as:

Width: 1= 292meters
Height: 1.14= 332.88meters
Length 1.39= 405.88meters

That would make a nice control room, and still leave about 3m for the live room, which is just about OK for a drum kit.

OK, so it is possible to build and treat a room that is higher than it is long, and that might be an option here, but Daniel will have to think about it: A ceiling 4 m above the ground is pretty high for a control room, and might be a problem from practical point of view (even simple things, like changing a light bulb, become harder that high).

But see below for adjustments, since there are other factors...

Are the "Golden Ratios" (like 1 - 1.14 - 1.39)? Or that 3 or 4 charts that i have, and each one says me one different thing...

Daniel, there are many good ratios, nit just one "best" or "golden" ratio. Smart scientists like Boner, Sepmeyer, Louden and others did lots of research on ratios years ago, and each has his own set of "good" ones. The thing is, if you plot out all those good ones on an X-Y graph, they all lie along a diagonal line, with a few "islands" around it. So you can choose any of the good ones, or even choose ones close to those, and you'll be fine. You don't need to go crazy about ratios. Just stay away from the bad ones, get close to the good ones, and that's it. 1 : 1.14 : 1.39 is Sepmeyer's second-best ratio, if I recall correctly, and that's great.

These existing walls are 15cm brick/concrete.

Great! That's a good outer-leaf. All you need to do to that is to seal the surface, by painting it with something that seals brick/concrete well.

Dimensions above are without any isolation (i think 10cm of isolation at each wall will be good...).

10 cm is the minimum air gap that you want for good isolation. More is better. An air gap of 15cm would be better, and 20 is really good. But that does not consider the thickness of the drywall. 3 layers of 16mm drywall adds about 5cm, so your total wall width (from the inside of the concrete/brick wall to the inside of the room) will be about 20 to 25 cm.

Now, the room-ratio dimensions must be measured on the final inside surface of the room, meaning the surface of the inner leaf that you see when you stand inside the room.

So, that means your maximum room width can only ever be 2.92 -.2 -.2 = 2.52. call it 2.5 m, to make it easy. So that means your dimensions would become:

Width: 1= 2.5 meters
Height: 1.14= 2.85 meters
Length 1.39= 3.475 meters

Once again, you COULD make the room 3.475 high and 2.85 long, to leave more space for the live room, but do you really want a room that is higher than it is long? There are pros and cons....

Will record drums, guitars and voice. Neighbors are a problem, so i need a good isolation. The room is in the 2nd floor.

Second floor is a problem! You are going to need to use lots of HEAVY materials to isolate this room, because "Neighbors are a problem" (so you need lots of isolation), and also "Will record drums". so you need lots of LOW FREQUENCY isolation. That implies mass, and lots of it. You will need a structural engineer to inspect the building and tell you if the floor can handle the huge load that you need to build on top of it. There will be many tons (yes, tons) of materials going into that room: you do not want the floor collapsing under you!

So first do a rough calculation of the weight, considering 3 layers of 15mm drywall all around, (all four walls, plus ceiling), then add in the framing, windows, doors, treatment, and equipment. That total is what you need to give to the structural engineer, and tell him it will all be concentrated around the edges of the room, about 20cm in from the existing walls. If he tells you that it is OK to do that, then we can go ahead with the design. If not, then you will have to figure out how to reinforce the floor enough to handle that.

whoa... with a room that is 7030 meters x 2920 meters, you may want to consider building more than two rooms

Yeah, but don't forget Daniel is from Brazil, and in Latin-speaking countries the comma is used as the decimal point, and the dot is the thousands separator. Confusing!

- Stuart -

Thanks Beau and Stuart!

Width: 1= 292meters
Height: 1.14= 332.88meters
Length 1.39= 405.88meters

That would make a nice control room, and still leave about 3m for the live room, which is just about OK for a drum kit.

Exactly what i was thinking. And a 3.32m height is ok (not too higher).

1 : 1.14 : 1.39 is Sepmeyer's second-best ratio, if I recall correctly

Is the first Sepmeyer best ratio, very great!

10 cm is the minimum air gap that you want for good isolation. More is better. An air gap of 15cm would be better, and 20 is really good. But that does not consider the thickness of the drywall. 3 layers of 16mm drywall adds about 5cm, so your total wall width (from the inside of the concrete/brick wall to the inside of the room) will be about 20 to 25 cm.

Now, the room-ratio dimensions must be measured on the final inside surface of the room, meaning the surface of the inner leaf that you see when you stand inside the room.

So, that means your maximum room width can only ever be 2.92 -.2 -.2 = 2.52. call it 2.5 m, to make it easy. So that means your dimensions would become:

Width: 1= 2.5 meters
Height: 1.14= 2.85 meters
Length 1.39= 3.475 meters

Really, you're reading my thoughts... I think that 20cm to the isolation is a good thing in this small room. But you think something like 15cm total (inside brick-inside room) is little?

Second floor is a problem! You are going to need to use lots of HEAVY materials to isolate this room, because "Neighbors are a problem" (so you need lots of isolation), and also "Will record drums". so you need lots of LOW FREQUENCY isolation

Yeah. Well, is in the 2nd floor, but the first floor below is my garage (no problem if some sound passes) (the neighbors are in the sides, about 5-10 meters away. Is a two floor house. Since my garage is below, i have freedom to put the structural reinforcement. Sure i will contact a engineer to make the thing secure and with no risks. But i think the floor will have to be insulation + wood. No more concrete.

Yeah, but don't forget Daniel is from Brazil, and in Latin-speaking countries the comma is used as the decimal point, and the dot is the thousands separator. Confusing!

Yes, we use comma instead dot. But i will use dots here. Anyway, i'm writing (very bad) in english too...

Well, i will update the sketch with new dimensions, and will post here.

Thanks a lot!

As i promissed:



That desk is too big... My will be smaller...

In this sketch, distance from inside concrete wall to inside room is 20cm.

A little question: In this situation, the CONTROL ROOM are with the 1 - 1:14 - 1:39 ratio and the "live" room no. Is this the best? Or is best reverse (let the best ratio for the "live" room)?

So, if this dimensions are good, will go ahead with project. Next step will be the angle of the walls...

Two suggestions:

1) Put the doors in the middle of the walls, instead of in the corners. You need the corners for bass trapping, soffit mounting, and other treatment.

2) Your side walls are coupled! You need to cut the side walls so that there is no physical connection between the LR and CR.

And it is more important for the CR to have a good ratio: The LR can have variable treatment, and should have some sort of "character" of its own, but the CR should be smooth, flat, and neutral.

In this sketch, distance from inside concrete wall to inside room is 20cm.

Should be fine. That gives you 15cm air gap, plus 5 for drywall. Should be excellent isolation!

- Stuart -

- Stuart -

Stuart, i agree 100%! You are helping a lot!

And the doors can be glass doors, to provide visual comunication, instead of the glass window.

Much better!

- Stuart -

"Are the "Golden Ratios" (like 1 - 1.14 - 1.39)? Or that 3 or 4 charts that i have, and each one says me one different thing... "


The Golden ratio is an irrational mathematical constant.

It has nothing to do with acoustic ratios and has been around far far longer. Not longer than acoustics, just longer than the specialized math as we know it. Certainly longer than Loudan, Sepmeyer, et. al.

No disrespect...it is what it is.

http://en.wikipedia.org/wiki/Golden_ratio


Actually, a room constructed using this ratio will be HUGE...which is a good thing...but huge seems to be something that doesn't go along with a personal audio environment.


Read that wiki link above, you'll feel smarter almost immediately

Hi Brien!

I read the arcticle... Is really interesting, but don't sure if the Golden ratios are good in acoustic or not. I thonk modes are best, but in small rooms, anything inside changes the response.

So, the main question is: How to determine the best dimensions for a room with limited space? What are the correct approach?

About the ratios, i find it first in this book.

And i think, if for a small room, the modal charts don't help (any milimeter changes all drastically...), a "golden" ratio and a good acoustic treatment is the best option.

But the question continues...

Daniel, I think Brien's point was that "the golden ratio" and good modal ratios for rooms are two different things! The golden ration is a mathematical concept, and there is only one single answer. "Room ratios for good modal response" is a whole universe, and there are no correct answers at all! If you draw an x:y graph of all possible room ratios (length vs. width, where the height is assumed to be 1), then you find that there are many "really bad" ratios and many "really good" ratios, with a whole lot of ranges of "mediocre" in between.

The whole concept of "room ratios" is very blurry itself: It is all about choosing a ratio that spreads out your lowest modes as evenly as possible (on the frequency spectrum), with no big gaps between any two adjacent modes, and also no modes too close together. A noble concept, but hard to define! What does "evenly spread" mean? What does "too far apart" mean? What does "too close together" mean? Ask ten acousticians what those terms mean, and you'll get at least twenty answers! Add to that the issue of what TYPE of modes should be considered, and how to account for them, and the issue gets really muddy. Should you only consider axial modes, or are tangentials and obliques important too? And iff you consider tangentials and obliques, then in what proportion? Are tangentials 3db down and obliques 6db down? Or tangential 10db down and obliques 20db down? Or are they all worth the same? Or some other proportion? The calculations get to be really complex.

And all of that is only true for perfectly rectangular rooms: if the room has more than six sides (four walls, floor, ceiling), or it any of the walls are angled slightly, or curved, then you can forget all about calculating ratios: They don't make sense any more.

To make it even more complicated, reality usually does not match prediction anyway. So you can use the best acoustic prediction software in the world to predict modal response, build your room, then analyze the actual response, and most likely the two graphs will not match. They might be close, but the will not match exactly. Theory and reality don't often agree absolutely, in acoustics. Even apparently minor errors in construction can make a difference in how the room behaves, plus the very fact of you standing in the room with the analysis equipment is going to change its behavior!

So why bother? Anything you put in the room is going to have an effect, so the final room response will not be the same as what your "perfect ratio" predicted, no matter how perfect the ratio is.

In other words, the concept of ratios is very nice theoretically, but not very useful in practice.

So the basic idea is this: Don't worry about it so much! Look at the dimensions of the space you have available, see where that ratio falls on the x:y graph of all possible ratios, and see how far away you are to the "bad" ones, and how close you are to the "good" ones. If you are already close to a couple of good ones, then that's it: you are done! End of story! No more worry required. If you are close to some bad ones, then think about how you could change the position of one wall (or maybe two) to get further away from the "bad" ones, and closer to the "good" ones.

That's it! It doesn't need to be more complex than that, because in a small room you will ALWAYS have modal issues, no matter WHAT ratio you use. It is impossible to find a "perfect" ratio for a small room, because no such things exists. The modes will always be there, and they will never be spread absolutely evenly, even with the best ratios.

That's one of the reasons why you will TREAT your room after it is built: to help smooth out the modal issues a bit. Your room WILL need treatment, regardless of what ratio you use! There simply is no doubt about that. You will HAVE to put in lots of bass trapping, without any doubt at all, simply because it is a small room. There is no question about it.

So if you are going to have to treat it anyway, and the best treatment to start with is large amounts of broad-band bass trapping, why get all crazy about room modes up front?

So just look for a reasonable ratio, and don't sweat it any more.


- Stuart -

Well said....

That's it! It doesn't need to be more complex than that, because in a small room you will ALWAYS have modal issues, no matter WHAT ratio you use. It is impossible to find a "perfect" ratio for a small room, because no such things exists. The modes will always be there, and they will never be spread absolutely evenly, even with the best ratios.

That's one of the reasons why you will TREAT your room after it is built: to help smooth out the modal issues a bit. Your room WILL need treatment, regardless of what ratio you use! There simply is no doubt about that. You will HAVE to put in lots of bass trapping, without any doubt at all, simply because it is a small room. There is no question about it.

Yeah, and i think my first answer is clear for me now.

Small room:

1 - Take a good known ratio (ROOM ratio), use it, apply the basic treatment (at this point that ratio is no longer that ratio...).Atention on bass frequencies - a nightmare in small rooms.
2 - Analyse your room, apply the corrective and final treatment and be happy!

I'll use the dimensions of sketch above, and inclined to use this LR part for my LR and this for the CR.

Yup! Looks like you got it!

The only thing I'd add to the CR, is soffit mounting (flush mounting) for your speakers. Very, very recommendable.


- Stuart -