Loudness and room-size was: TV-Mix for Theatre

[garnoil]

Originally Posted by airon

I had that very problem just three weeks ago, as we mixed a short for theatrical presentation. In a test screening, in which the playback chain was set to Dolby standards(7), the whole mix was 2-3 dB more quiet than in our somewhat small room we mixed it in. I'd already tried to compensate for the roomsize by using 82dB as a reference point, but it seems for the bandlimited pink noise (Bluesky file) and even Dolby noise this was not enough. I had to go to 79 dB SPL to get a comparable response in the theater we screened at. Several factors could and probably will have skewed the perceptions. The accoustics in both the theater and mixing room, as well as the speaker placement in the mixing room.

There's always a lot to check.

You may have also noticed that certain frequency band translate better than others. Going from a non-corrected small room to a Dolby aligned dub theatre you may fine: Generally dialogue will be 4 to 6 db low, high end will sound brighter, and low end will be lacking in the 80 to 200 Hz region. Anything between 400Hz and 1K will probably sound quite similar in both rooms.

[Postman]

This will lead to a false SPL reading that will be artificially high because the non-linearity of the low end.

No. Low end non-linearity affecting SPL meters can be avoided by using narrow band pink noise. The difference between large and small rooms is apparently more involved than that. I personally believe it is more about speaker-listener distance. Why I don't know, but having speakers 3 feet away in a small room, and then moving 8 feet away in the same room, results in a VERY different, and more reliable, mix.

Everything else you said, about dialog being low and hi frequencies being stronger in a film theater, are mostly opposite to my own experiences. Bass lacking from 40-200 is so dependent on room characteristics that I don't know why you've even tried to quantify it. It is just as likely that bass will sound stronger in a film theater. Trying to compare a "non-corrected small room" to anything else is supposition.

[garnoil]

Originally Posted by Postman

No. Low end non-linearity affecting SPL meters can be avoided by using narrow band pink noise. The difference between large and small rooms is apparently more involved than that. I personally believe it is more about speaker-listener distance. Why I don't know, but having speakers 3 feet away in a small room, and then moving 8 feet away in the same room, results in a VERY different, and more reliable, mix.

Everything else you said, about dialog being low and hi frequencies being stronger in a film theater, are mostly opposite to my own experiences. Bass lacking from 40-200 is so dependent on room characteristics that I don't know why you've even tried to quantify it. It is just as likely that bass will sound stronger in a film theater. Trying to compare a "non-corrected small room" to anything else is supposition.

I never said "Bass lacking from 40-200 is so dependent on room characteristics that I don't know why you've even tried to quantify it." I said "low end will be lacking in the 80 to 200 Hz region" because these is where the strongest resonances in an un-corrected room will appear and one mixes opposite to the response of the room. I am referring to a small room of about 14 X 18 X 9.

Not everybody is using "narrow band pink noise" to align their rooms. I agree with you that if you are using narrow band pink, an RTA, and are able to correct the room acoustically (bass traps, frequency dependent absorption at problem ranges, have full frequency speakers properly located, etc) the room would probably translate quite well to a theatre but many rooms are not like that. I also agree that smaller rooms that want to pre-mix for film should make an effort to be like that, but that is just not the case. There is a "generalization" that appears to exists that if one simply runs pink at 85 it will all be fine. I am saying that it is NOT fine and that unless one works on the room as well as the aligning it one will have small-er rooms that simply do not translate well to large rooms.

As far as the differences of what one hears between a large dub/movie theatre and a small room, most movie theatres have extensive absorption at the higher end of the frequency spectrum. I have never meassured a movie theatre's frequency banded RT60 but I would bet that it is very short on the high end (almost no high end reverb time). In fact, I doubt that there is any significant sound reflections of the high end frequency spectrum at a movie theatre. In an un-corrected small room (just a typical room with some acoustic material but not professionally designed), there would be considerable room reflections and unless the small room is fully padded with high end absorbing material (lime a movie theatre is) the small room is going to sound brighter "at least appear to sound brighter dues to the higher time value of the RT60 in the upper bands" - in the mid sound field not 3 feet away from the speaker- than a large room where almost no high end reflection exists.

[dr sound]

Garnoil,
Call me. I would like to talk with you.

[garnoil]

Originally Posted by dr sound

Garnoil,
Call me. I would like to talk with you.

I am not based in the US but I'll shoot you an e-mail and go from there.

G