New Studio Room

[t.vanbaden]

Hello everybody,

I am building a new room where I am going to record vocals, acoustic guitars, brass instruments and general overdubs, mix and use as a control room.

The dimensions are: 450cm length, 270 width and 240 height.

I have calculated some of the standing waves that would occur (mathematically, not actual measuring)

125hz on the length.
209hz on the width.
235hz on the height.

244hz combined length and width.
266hz combined length and height.
314 combined width and height.

and off coarse all the summing-ups of these waves and the 3ths.

I think the best way is to start with is some broadband absorbers that go as low as 125hz with an 0.6 effective absorption-coefficient minimally in all the corners. After it I think I will measure the waves that still occur and construct tuned traps for them in places they would likely build up.

If I am thinking wrong or if you have some advice to this approach I would be very happy because I am far from an expert in the field of acoustics.

my goal is to absorb these standing waves and create a far better recording space (in an acoustic way) , I am absolutely not trying to isolate sound from the outside to the inside or the other way around!!!

Any thoughts on this subject would be welcome!

Thanks,

Teike van Baden

 

[jhbrandt]

Teike,

You seem to be on the right track, but I think that you will find that you need more trapping. I do not recommend 'targeting' bass frequencies but if you do use tuned trapping, you can cover what you need with an array of 'tuned' traps covering about 1/3 octave each & extending over the frequency range of interest. You need to try for an absorption coefficient of at least .8 for optimal absorption. You will not be able to stop these waves or bring their decay down to one cycle without non-environment style trapping.
The problem with your room is that it is only 29 cubic meters whereas the minimum recommended is 42 m3. You want the modal support. You want the boundaries to support the sound evenly within the enclosure. A room with less than 42 m3 will have large spaces between each standing wave and therefore no support for note that fall into this area. For instance; Your room has an axial mode at 143.5Hz and the next lowest mode is tangential at 135.4Hz. Now D3 on the piano is 146.832Hz & the next lowest note, C♯3/D♭3, is 138.591Hz which falls into the hole between the two modal room resonances. Therefore C♯3/D♭3 will possibly sound about 3 - 6db LOWER in level. Trapping will improve this. But as you go lower the modal sparsity causes too many dips in the frequency response so that below the 1/3 octave band of 63Hz, the room will not respond accurately, no matter how much trapping you do.

I have some useful calculators and several articles that can help you on my publications page and there are some very good articles on the RealTraps site and the GIK site.

Good luck! You are on the right track starting with the trapping.

Cheers,
John