Combining music,tv-post and theatermixing

[pethenis]

Odd question: Would it be possible to build a usable room where you can have two mixing positions? One for music and TV, where the mix position would be a third in the room from the front and one actually a third from the back, using LCR behind a perforated screen and surrounds on the wall (mini dubstage for premixing cinema). ANY thoughts on construction and treatment appreciated!

[boggy]

Originally Posted by pethenis

Odd question: Would it be possible to build a usable room where you can have two mixing positions? One for music and TV, where the mix position would be a third in the room from the front and one actually a third from the back, using LCR behind a perforated screen and surrounds on the wall (mini dubstage for premixing cinema). ANY thoughts on construction and treatment appreciated!

It is rally possible to find a two frontward/backward symmetrical listening/loudspeaker positions in same room. Room needs to be fairly big ...

For acoustic treatment I recommend something that not have different front and back treatment like MyRoom Design. Basic principles are that you need to have a heavy LF wideband apsorption treatment at all surfaces excluding floor, and also air transparent diffusion over all absorption surfaces. Less expensive version may be without air transparent diffusers based on Schroeder formula, but with binary diffusers over LF absorption treatment.

[pethenis]

Thanks, that's a really interesting read, it will take me a while to get that "under the hood" ;-) I think I understand the principle of the air transparent diffusion before broadband absorption. Couple of questions if you have time:

Any layman reading regarding the Schroeder formula?
How long did it take to treat the room and cost per m2?
What do you mean by the binary diffusors?

Originally Posted by boggy

It is rally possible to find a two frontward/backward symmetrical listening/loudspeaker positions in same room. Room needs to be fairly big ...

For acoustic treatment I recommend something that not have different front and back treatment like MyRoom Design. Basic principles are that you need to have a heavy LF wideband apsorption treatment at all surfaces excluding floor, and also air transparent diffusion over all absorption surfaces. Less expensive version may be without air transparent diffusers based on Schroeder formula, but with binary diffusers over LF absorption treatment.

[boggy]

I will try:

Originally Posted by pethenis

...........
Any layman reading regarding the Schroeder formula?

I don't know for any "layman" document, I always use:
The Schroeder Quadratic-Residue Diffusor: Design Theory and Application , P. D'Antonio, J. Konnert, 74th AES Convention, New York, 1983.
You can find more about diffusers in this book:
Amazon.com: Acoustic Absorbers and Diffusers: Theory, Design and Application; TREVOR COX, Peter D'Antonio

There are a free software which can do calculation for you named QRDude, but we rarely use it (we use our software)

Originally Posted by pethenis

How long did it take to treat the room

It depends on many local parameters, including size of the room....
Smaller room with dimensions 4x5x3m may be finished for about one month with good organisation and good craftsman(s)... but we have studios that are(n't) built for more than two years (not enough money) and one recent that is built for about 15 days.... even if there aren't many differences between it, at least not in complexity of design, both has binary diffusers in front... nothing too difficult and too expensive... but there may be always some (subjective and objective) reasons...
Also we don't have our workers, we are a designers only.

Originally Posted by pethenis

and cost per m2?

Some costs depends really on surface size, but main absorption treatment depends on the volume of treatment that may vary. Main absorption treatment, in the small room, spend about 30-50% of room volume if you like to have your room modes dampened enough to have a decent low frequency response (all people like this, professionals and amateurs), and to get your measured response enough good to satisfy some of this recomendations:

1. "Multichannel surround sound systems and operations", AES Technical Council, Document AESTD1001.1.01-10, New York.
2. “Methods for the subjective assessment of small impairments in audio systems including multichannel sound systems”, ITU-R Recommendation BS.1116 (rev. 1), ITU, Geneva, 1997.
3. W. Hoeg, L. Christensen, R. Walker, “Subjective assessment of audio quality– the means and methods within the EBU”, EBU Technical Review Winter 1997, pp. 40-43.
4. "Listening conditions for the assessment of sound programme material: monophonic and two–channel stereophonic", EBU Tech. 3276 – 2nd edition May 1998, European Broadcasting Union, Geneva, Switzerland

We usually do three different layers of treatment, basic wooden frame next to wall, with first layer of absorption (surface dependent), Hidley/Newell panels in the middle (volume dependent) and diffusion layer with his wooden frame (surface dependent), in front of all this.

It's all depends on particular design but I can give you some information about costs of materials here in Serbia, so, your local prices may be different...:

1. primary frame with ordinary limp mass absorption may costs about 30EUR/m2 (in this place, absorption like modex plate from RPG costs more, but works much better)

2. absorption "in the middle", Hidley/Newell panels, costs about 120EUR/m3 (volume dependent!)

3a. QRD based air transparent diffuser costs about 80EUR/m2 for very basic version (lacquered OSB) with frame for supporting and some aesthetic (wooden) covering for it... using veneered particle board for building diffusers is better but it is more expensive and price depends also on type of veneer and finishing.

3b. For binary diffusion with slats built from fir or linden/tilia (real wood) costs about 30EUR/m2 with frame for supporting, some fabric, lacquering and some aesthetic wooden covering.

In price isn't included labor, design and support, but I hope that you can build some picture about costs.

All listed here didn't include spending room volume, money and time for sound and vibration isolation. Only acoustical treatment is described.

Originally Posted by pethenis

What do you mean by the binary diffusors?

When I wrote "binary diffuser" I mean amplitude grating diffusion structure where absorption and reflection regions alternate following random or pseudo-random binary sequence where "0" may be absorption and "1" reflection. Structure may be one dimensional or two dimensional. One of two dimensional structures is commercial product called BAD panel from RPG Inc (patent).

More about topic you can find in following GS threads:
DIY Binary Amplitude Diffuser anyone?
Calculating slat / slot width for a binary diffuser
Can bamboo wall treatment help dead room?

[pethenis]

Thanks Boggy, that's a generous answer, thanks for taking the time. I'm moving studio in a year, have to buil a new one, now's the time to do the research...