John Sayers' Recording Studio Design Forum Archive

Hello everybody !

Please forgive some questions from a newbie, I checked a lot of posts on the forum without finding a reply to my doubts (well, I'm pretty sure you will tell me I have miss the right ones ).

First of all, let me say that my interest is, for the moment, theoretical as I do not have (not yet, at least) a room for building my studio, but I REALLY hope this will change very soon !

I'm studying the design of John for wall units and there are a couple of things not very clear to me.

1) The formula for calculating the Helmotz absorber is based on the distance from the wall of the box. But in case of a corner unit, which distance should I consider ?

2) John suggest to alternate size of slats and of gaps on the front of the absorber, but is this really necessary ? I guess this will help to widen the bandwidth of the absorber, but how to use the formula to consider these variables ?

3) I am currently "playing" with a software called CARA (www.cara.de), that should help me with the design of the room from the acoustic point of view. For those who do not know this SW , it contains a sort of CAD for 3D objects to be later on placed in the room and each object is defined by its physical dimensions and its acoustical characteristics.
I wonder if it is possible to load the characteristics of the units as per John's design : of course size is not a problem as can be easily measured (or defined in advance) but what about the absorption (alpha) coefficient of these units at various frequencies ? Does anybody have some data for units he already built ?

Many thanks in advance to all who will have the patience to read and (possibly) reply to my questions.

Have a nice day !

Marco

MarcoSan wrote: I am currently "playing" with a software called CARA (www.cara.de), that should help me with the design of the room from the acoustic point of view. For those who do not know this SW , it contains a sort of CAD for 3D objects to be later on placed in the room and each object is defined by its physical dimensions and its acoustical characteristics.

Hi and welcome!!

I can't really answer your questions in as much detail as John could but I would really like to hear how that SW works out. It looks pretty neat!

Ron

Hello VSpaceBoy !

CARA stands for Computer Aided Room Design and is a software developed by the german company ELAC. In the USA, accordingly to the coversheet notes, is distributed by Rhintek In. (www.rhintek.com).

I'm still a beginner with this sw and I can only give you an overview of its functions.

First of all, you can design your room, starting from some basic and most common shapes. Then you can define the type of surface (material and covered area) : here is where you add windows and doors, for example.

Then you add the furniture and other 3D objects. But before doing this, you have to create the object in a specific library if it does not exists. To do so, you need (a) physical dimensions of the object -and- (b) its acoustic characteristic, in terms of its absorption at various frequencies.

Done this second step, its time to position the loudspeakers (CARA support up to 8.1 surround systems) and to define the listener position.
Concerning the loudspeakers, CARA has a certain "library" of predefined speakers but it is possible to create a model for your own brand/model.

Now is time to run calculations and simulations : you can look for the best possible loudspeakers/listener position, you can calculate the frequency response within the room, you can display the reverberation diagram of the room. Other functions may be possible but they don't come to my mind now.

If you buy a certain package (what I did), you get also a sort of "video tutorial" on a second CD and a third CD full of test signals.

All the above at a quite resonable price ( I paid about 76 EURO for the three-CD package including shipping from Germany to Italy by courier).

Well, before spending a lot of money, time, efforts and resources into a trial-and-error studio building I prefer to give this software a try. Later on, if needed, I will give the final touch using my ears.

Of course I have no interest of any kind in promoting this sw, I am simply an user who found an (what I think is) interesting tool.
For any additional info, please refer to the CARA website.

But now, what about giving me some hints to my questions ?

Have a nice day !

Marco

Marco