John Sayers' Recording Studio Design Forum Archive

Hi all,

First of all thank you for this site it is always a great read and a very valuable source of information

I have been a long time reader but a first time poster

After a long time i have finaly managed to be able to construct a small studio of my own!

I have been designing a small home/basement studio so I can mix and record music and do film post production.

As I do quite a lot of post production work, one of my design criteria has been to be able to mix tv and short films in 5.1 as well to record foley and adr.

The studio will be build in the basement of a new house (not yet built). The house will be build using standard concrete frame and concrete basement walls.

The design includes a control and a live room,
The control room is (H-W-L) 3m x 3.42m x 4.17m Ratio( 1 : 1.22 : 1.39)
Live room is (H-W-L) 3m x 3.90m x 5.70m ratio (1 : 1.30 : 1:90)

Since the house has not been built yet I will be constructing 2 separate concrete slabs where the rooms will be built upon. Which in turn should isolate the two rooms from each other and from the structure of the house. This slab will have a 10cm air gab from the houses outer wall which will be concrete. The house is in a quiet area therefore isolation is very important.

The studio walls will be constructed with 2 layers of plasterboard insulated with Rockwool (75kg/m2). The celling will also be floated from the celling concrete slab.
One of my concerns is the layout of the control room. I have found the sweet spot of the room based on the 38% rule, and I found out that the speakers would be placed quite far from the rooms corners. I had been planning on soffiting the LCR speakers, is there a way to change the rooms dimensions/ layout to incorporate a soffit design. I would assume that the room would have to change from being rectangular to different shape.

Changing the design of the room might give me space for a vocal booth which would be great.
I would also be glad for any suggestions on room treatment. I have been planning on constructing 4 large bass traps for the rooms corners (including 2 with soffit speakers) a cloud over the mix position and a couple of panels for the first reflection points. Would it help acoustics if I made bass traps on the celling corners also.


1. How can the control room change to incorporate a LCR soffit design
2. What is the recomended speaker placement for the controll room
3. Are the live room dimensions ok and can the layout be changed to something better.
4. Can a vocal booth be placed somewhere in the studio
5. Any further suggestions on room treatment

I have attached a sketchup plan of the studio.
And a picture for quick reference
Any help or comments will be greately appretiated

Thanks

I would seriously recommend switching the uses of the rooms CR<->TR

This will put you in a better position to listen and tweak your mixes. As I always say, your Control room is the most important room in the studio. Also, these days, much recording is done in the same room.

How high will the ceilings be?

How much isolation do you need?

Cheers,
John

Hi and thenaks for the reply!

Height (after floating cealing) will be 3m

That's a nice height. Are the measurements to massive hard surfaces or to treatment? If you are building an inside-out wall for these, you should measure to the gypsum board. - Standard construction, however, will offer better transmission loss figures.

With the dimensions given your large room will have almost 67 cubic meters volume. Very nice. The Bonello distribution is good down to the 31.5Hz band, your LF region will be up to 150Hz after treatment, so focus trapping from 200Hz and down. These dimensions show good modal spacing.

You could do a double slant (after Geddes) to the north wall of the tracking room (smaller room) and still keep some ambiance in that small room - maybe corner polys in a couple of the corners... Ceiling absorptive.

In the control room the entire front section of the ceiling can be a huge corner trap - you can also run corner traps all down the wall/ceiling corner to the left and right of the mix position. And in the Tracking room these same upper corners can be utilized in the same manner. You almost can not over trap.. but you should do some measurements with REW or Fuzzmeasure to see where you are as you go. (you don't want to be spending money on treatment that is doing little good)

Cheers,
John

Thanks for your reply,

The room measurments are based on the hard surfaces (gystum board). The walls cross section will be as follows:

Outer concrete wall 20cm -> Airgap -> Framing with 75kg/m2 rockwool -> gystum board -> green glue -> gystum board.

The studio walls will be built on separated concrete slabs.

Would the small room be inefficient as a controll room?

Framing with 75kg/m2 rockwool

That is way too dense. 40 to 50 kg/m3 is optimum. Andre posted a link to this report a few days ago. You might find it interesting.


- Stuart -

The small room can work but it is right at the lowest limit of room volume, in my book. In the small room your lowest frequency with modal support will be 40Hz. That is really not too bad, but the problem with rooms of this volume is that the modal spacing is too wide in some cases. So in your room you will not have support the the notes; G♯2/A♭2, F♯2/G♭2, E2, and on down the keyboard. These start at around 100Hz.

What this means is that you can not skimp on Low Frequency absorption in the smaller room. Ideally, I will start with the mix/mastering room with dimensions to support 20Hz at least and then add the trapping to dampen the decay time and broaden the 'Q' of the modes.

It is always about compromise when we deal with a real world situation.

And for wall cavity insulation, you are better off with the cheaper, fluffy stuff. Fill it full to get the most benefit. Honestly, there is not too much difference in the effect of the different densities but the cost difference is big. Therefore, it is not cost effective to do more than fill the space with fluffy.

Cheers,
John