Italy > new control room + little dead room

Hi guys! I'm really sorry for my ugly english, but I'm from Italy and not so good writing (and speaking) your language. So please have some patience with me :oops: A new adventure for me next month... :P I'm planning to create a little control room + a little dead room in a place I'm starting to rent from the next week. I currently have spoke to the guy who do the most of the acoustic isolation here in Turin, so really I don't need an help with the details of using plasterboards, wood...etc because he is a professional on that. I also had a great experience some year ago with the construction of the professional studio where i work: http://www.bluroom.it/index.php?option= ... 3&Itemid=6 The fact is that this time is a low budget project, something about 10.000€, and really I can't pay the man who designed that studio (http://www.marcofringuellino.com/) So I need to choose the right dimensions and design to let the constructod follow a correct project. I'm really scarry to do mistakes because I studied Acoustic and I read a lot and I know that little rooms have more problems and problems are heavy in the bass frequencies.. So I hope you will help me choosing the right shape and acoustic solutions for this place! :idea: Details: -location: Turin (Italy), really near the Olimpic stadium, in a residential street, under a 6 floor building with a lot of families... the place is a basement. Under we have the cellars, in one side we have a shop and above we have a medical studio open only some hours during the day, but above the medical studio we have other 5 floors of apartments... - I will not record any loud instruments like drums or bass amps, but only voice, acoustic guitars... but I'm producing and mixing a lot of dance music, so the kick and the bass are pumping all the day :horse: My main monitors are a pair of ADAM S3X-H, so they are loud but usually I don't like to go abobe 80/90 db when i work.. And I really don't want to work at evening or at night... (I hope to make a more regular life...) -I can provide these documents at the moment, the sketchup 3d is taken from the 3d did with Acad, then tranfered to 3ds then to SkUP.. :) If this post is lacking of some detail please ask me what you need. And really thank you!

I'm playing with SketchUp but really 3D is not for me...I continue to prefer playing with the DAW :lol: I would like to know what would you do if you have a space like that, maybe someone imagine the c/r in another place...and something about the right room ratios... The .skp is working?

Why nobody try to tell something on this project? a simple advice, a consideration... :) Would be great for me to have an opinion. Thanks

I'm playing with SketchUp but really 3D is not for me...

Yeah, figuring out SketchUp does take some time! At first it seems strange and hard to use, but once you grasp a few of their "unusual" concepts, it turns out to be a really powerful, and very useful tool.

I would like to know what would you do if you have a space like that,

I think I would try to turn the control room around, so that it faces towards the booth, and put the door on the middle of the front wall (between the speaker soffits): You could have some glass in that door, to give you visibility between the two rooms. It's not a good idea to cut off the rear corners of your room diagonally, like you show: those corners are a very good place for bass traps.

and something about the right room ratios...

There are several good ratios, and I'm sure one of them would work for your studio, but you didn't give us any dimensions! Without know the size of the available space (including height) then there's not much we can do! Also, I don't speak Italian, so I don't know what the comments on that drawing mean. - Stuart -

These are the measures, and also the sketchup have the right measures. This is my idea right now. What do you think?

You are still cutting off the rear corners of your control room, which you will definitely need for bass traps. Also, I'd suggest that you put the isolation booth on the other side of the control room, in the corner. That would save a lot of space, as you would not need that soundlock entrance, and would also not need to go through the iso booth to get to the control room. - Stuart -

Thank you for the advice Stuart! I know the drawing let the most to imagination, so it's difficult to understand what I have in mind.. In effect those rear corners are the space to put the bass traps.. Putting the iso on the right of the control room means to have a really little booth. And you have to go trough the c/r to get in the iso. And I'm trying to avoid to have the entrance in front or in the rear of the control room. I will put a glass door. Can I ask you if the ratios in this project are good ones? Can someone suggest me from what frequency I have to do modal interpretations of this space and what calculations I have to do to understand the problems with this geometry?

it's difficult to understand what I have in mind..

It looks clear to me, in both the original rough sketch and also in the more detailed CAD plan. The problem is not that I don't understand what you have in mind: The problem is that you don't understand why it wont work!

In effect those rear corners are the space to put the bass traps..

That's impossible. I don't think you understand the concept of where the bass traps should go. Here: And also here. I have drawn red lines to show where the bass traps should be. It is impossible to put them there with your design, since there is a huge concrete pillar there, as well as the door! Like I said: you are cutting off the rear corners of your room, which is where the bass traps should be. That's a huge amount of wasted space.

Putting the iso on the right of the control room means to have a really little booth.

Not if you rotate the control room 90°, and lay out the rooms correctly...

And I'm trying to avoid to have the entrance in front or in the rear of the control room.

Why? Those are actually very good places to have doors! The middle of the front wall or the middle of the rear wall are excellent locations for doors. Much, much better than on the rear corner, where the bass trap should be!

Can I ask you if the ratios in this project are good ones?

The room is not rectangular: therefore you do not have a ratio. Right now, the room has six walls, a floor and a ceiling. Four of those walls are heavily splayed. Therefore it is impossible to calculate any "ratio" for that room: it does not have a simple rectangular shape, so there are no ratios. But there are still modes. With a hexagonal-prism shaped room like that, the only method for calculating the modal response is by using Finite Element Modeling and Finite Element Analysis. That is very complicated, and will cost you a lot of money. I don't think you need to do that. You have other major problems with that room too: the listening position seems to be in the geometric center, which is the worst possible place. The speakers are too close to the side walls, and too far from the front wall. The side walls are splayed at large angles but yo are still not achieving an RFZ, so it isn't worth trying, and you can reduce the splay angle considerably. And the overall section looks to be almost a square, so you don't need FEM/FEA to tell you that you are going to have major modal problems in there. What I would do if that were my room, is to forget that exotic hexagonal shape, and change it to a more conventional rectangular shape with 6° splay on the front half of the side walls. That will get you close enough to a rectangle that you actually can use ordinary tools to figure your modal response.

Can someone suggest me from what frequency I have to do modal interpretations of this space

Like I said, with that shape your only chance is to do full FEM/FEA analysis. That is not something you can do yourself. You will have to hire a company to do it for you, as you need an experienced operator to set the boundary conditions for the matrix, and then to interpret the results for you. That is expensive. There will not just be one frequency, but dozens of frequencies that you need to be worried about in a room like that.

and what calculations I have to do to understand the problems with this geometry?

There are no simple calculations or equations for non-rectangular rooms. You can only do that yourself if your room has four walls and is close to being a rectangle. The usual spreadsheets and web site calculators only work on rectangles. As soon as you have mote than four walls, or walls that are splayed at large angles, those calculators are no longer valid. The only way of figuring it out then is, like I said before, with FEM/FEA. With your hexagonal shape inner-leaf, you only have two axial directions (instead of the normal three), and one of those is only partial. So practically all of your modal issues will be tangential and oblique modes, plus even more complex ones that involve as many as eight surfaces. You cannot figure those easily. - Stuart -

Thank you Stuart for this reply. I'm agree for the modal response prevision, impossible without very difficult calculations. But I also studied that a square or rectangular space have really higher modal problems in comparison with a shape like this. And I also know that the bass traps are always putted in the angles, just because you have angles. If you avoid to create angles in the room you don't need to remove them with traps.. But these are my thoughts.. now I'm doubtful after your advices :) MUMBLE MUMBLE.....

... that a square or rectangular space have really higher modal problems in comparison with a shape like this.

No, that isn't true. All rooms have modes, regardless of the shape. Some web sites on the internet provide wrong information about how modes work, and about how to calculate them, so that's probably where you got the wrong idea. It might help to understand what a mode is, so let me explain: A "mode" is any path that a sound wave can take around the room, bouncing off the walls, and get back to the same place where it started in phase with itself. The wave might bounce off two walls to do that, in which case it is an axial mode, or it might bounce off four walls (a tangential mode) or more walls (an oblique mode). It doesn't matter how many walls it bounces off: if it gets back to the same point, going in the same direction, and in phase with itself, then it is a mode. It is a "standing wave" that remains in phase with itself as it moves around the room. So all rooms have modes. It does not matter what shape you make it, or how many walls you put around it, it will ALWAYS have modes. You CANNOT get rid of the modes by moving the walls. That is a myth. The only thing you change if you move a wall, is to alter the frequency that the mode will occur at. If you make the path longer, then the mode happens at a lower frequency. If you make the path shorter, then it happens at a higher frequency. But it still happens. It is also a myth that making the walls non-parallel will eliminate the modes: it does not. It might change modes from one type to another, but it does not eliminate them. So an axial mode might change into a tangential mode at a different frequency, but it is still there. Or a tangential mode might change into an oblique mode, but it is still there. Think about it: if you angle one side wall, all that you do is to make the sound waves bounce in a different direction. You do not stop the waves from bouncing by angling the walls: you just change the direction that they go. So, all rooms have modes, and it is impossible to eliminate them by angling walls. In fact, with your room shape, you have only changed the axial modes across the width of the room: the axial modes for the length and height are still exactly the same, and so are many of the tangential and oblique modes. Yes, it is true that tangential modes occur 3dB lower than axials, and oblique modes are another 3 dB below that, but they are still there, and will still cause problems. And 3dB is not a big change: you can only just notice the difference. So all that you accomplish by angling the walls, is to make it impossible to calculate the modal response for the room with simple spreadsheets! You can no longer calculate if your modal spread (Bonello diagram) is smooth or not. You just make your job harder.

And I also know that the bass traps are always putted in the angles, just because you have angles. If you avoid to create angles in the room you don't need to remove them with traps..

Actually, that isn't true either! The modes are not due to the corners: they are due to the WALLS! And bass traps don't go in the corners because they create modes: they go in the corners because that is the best place to put them, so that they have the most effect! Even if you make your room into a cylinder shape, or a sphere (no corners at all) there will STILL be modes. (The only difference is that all the modes will now occur at the exact same frequencies and octave spacing, with very, very poor spread, so you will have terrible problems with the modes in a round room). And the reason why you put bass traps in the corners is because that is the most effective place for them, acoustically. It is the location where they work most efficiently. If you put a bass trap against a wall, then the wall gives it a 6 dB increase in effectiveness since the wave gets treated twice: once going in, and the second time going back out again. If you put the bass trap in the corner between two walls, then it gets ANOTHER 6 dB increase in effectiveness, for a total of 12 dB. If you put it in the "tri-corner" where three surfaces meet (wall-wall-floor, or wall-wall-ceiling) then you get an 18 dB increase in effectiveness. So traps in corners work much, much better than traps placed elsewhere. The other reason why you put bass taps in corners, is because ALL room modes terminate in the corners. So if you put it in the corner, you KNOW that you are treating all the modes, not missing any of them. If you put a bass trap against a wall, then you are only treating the modes associated with that wall, and will not do anything for modes that don't happen to bounce off that wall. For example, if you put a bass trap on the ceiling, then that will do nothing at all for the axial modes associated with the length of the room, or the width of the room, and it will do nothing for the tangential modes associated with length and width. If it is not in the corner, then it cannot treat those modes, and so it is not effective as a bass trap. I think the reason why you thought that square and rectangular shapes are worse than yours, is because you were considering perfectly square of perfectly rectangular rooms, where the dimensions are directly related to each other. For example, a room 2m high, 4m wide and 8m long will, indeed, have terrible modal problems, since the modes will all occur at the same frequencies. So yes, a square shape is bad, and the worst possible shape is a cube, but rectangles are good, provided that the "ratio" of the dimensions is not directly related. For example, a room that is 2m high, 2.28m wide, and 2.78m long actually has a very good modal distribution: that is Sepmeyer's first ratio (Sepmeyer is a scientist who studied acoustics and how sound waves interact with rooms). That room has a very smooth Bonello diagram. A room that measures 2m high, 2.8m wide and 3.8m long also has a very good modal distribution: that is Louden's first ratio (Louden is another scientist who studied acoustics). There are many good ratios that have been found by several scientists (Bolt, Volkman, Boner, etc.), and today there are tools that you can use to analyze room ratios, and see if yours is good or not. But in general, the fact is that ALL rooms have modes, regardless of the shape or angles, and therefore ALL rooms need bass traps. The smaller a room is, the more bass traps it needs. Your room is very small, and it will need a LOT of bass trapping. Large rooms do not need so much bass trapping, since they have many more possible modes, and they are spaced closer together. But for a small room there are only a few possible modes, and they are spaced far apart, so small rooms need a lot of treatment to help deal with that. If you would like to understand these principles better, I'd suggest that you read "Master handbook of Acoustics", by F. Alton Everest. It explains the theory of acoustics very well. Another really good place to learn about modes and ratios, is here: http://forum.studiotips.com/viewtopic.php?t=684 That's about the best one I ever saw on the Internet. So I would strongly suggest that you change the shape of your room, by putting the corners back in ad adjusting the angles of the walls. Because you cut off the corners, you have made the total room volume SMALLER, which means that the modal problems will be worse, and you cannot even predict them. You also cannot treat them, since you don't have enough space to put bass traps in! If you change the shape to what it should be, then there will be more air volume in the room, which means fewer modal problems, and you will also have the corners to put bass traps in. - Stuart -

Thank you a lot! You're very accurate and precious. I'm thinking a lot about this project..... :roll: