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Room Calibration - ATSC Standards - Help
Need a little guidance (Marti?)
I'm re-calibrating my room... 1027 cubic feet. I've followed the ATSC standard that Marti posted at the top of the forum (sticky). 1) I calibrated my system with the 440 signal. I'm on an LE 003 Rack system with a Durrough stereo digital meter. I've calibrated the 003 volume knob to make the Durrough read -20dbfs per channel (2). 2) I used the band-limited pink noise and my SPL monitor controller volume knob and Radioshack digital SPL meter to calibrate the level at 76, as per the cubic size of my room. I set the volume knob and marked the position, each speaker measures the same level. 3) Here's my problem. I downloaded the speech sample that the ATSC paper mentioned, dubbed it to stereo and played the file (they say it's measured at -24 LKFS (loudness)). When I play this file it's very loud, not at all what I would mix at. They say adjust for comfortable mixing level but can't figure why they'd have me go and change any levels. I thought this was calibration. If I do change the level to a normal one, a listening level I'd mix Dx at, then the speech falls at -31dbfs, or around there. Is this right???? I'm posting the last paragraph from the ATSC paper for clarification. I appreciate any help in figuring this step out. -Mike ---------------- Quote:
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Re: Room Calibration - ATSC Standards - Help
what SPL did you calibrate to? 1027 cubic feet is considered "small". Keep in mind most hollywood dub stages are anywhere from 40,000 to 60,000 cubic feet. A lot of the dub stage calibration specs are written for these size rooms. When the speakers get closer and closer to you, their apparent loudness goes up, meaning a speaker 20ft away calibrated to 85dB SPL will feel quieter than a speaker 5 ft away calibrated to the same 85dB SPL. Depending on how close you are to the speakers, you might have to calibrate to a lower level for it to "feel" and/or "sound" correct in your room.
The experience you are describing with the ATSC dialogue sounds like you are encountering the acoustic anomaly I'm describing above. I think dolby (anyone, please correct me if I'm mistaken) specifies that you need to be at least 13 ft 4 inches away from your front speakers in order to use the 85dB SPL ref level. But to me even that seems pretty close and might need to be calibrated to 82dB or something instead of 85. In the end, use your ears. 99% of the time they are correct.
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Derek Jones Sound Engineer / Producer / Composer Derek Jones Linkedin Megatrax Recording Studios Megatrax Studios Yelp Page A-list Music Artist Page |
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Re: Room Calibration - ATSC Standards - Help
I would try 82 spl and see how it sounds. If it is still too loud try
going down in 1db steps until it sounds right. If it's below 78, you better check it in a calibrated dub stage.
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Marti D. Humphrey CAS aka dr.sound www.thedubstage.com IMDB http://www.imdb.com/name/nm0401937/ Like everything in life, there are no guarantees just opportunities. |
#4
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Re: Room Calibration - ATSC Standards - Help
Quote:
If it's any help... most feature films are said to have an average dialogue level of around -27dBfs to -31dBfs. But when mixing, they aren't looking at the meters to make sure it hits those numbers. That's just kind of how it works out when adjusting levels by ear in a calibrated room. So maybe you aren't that far off after all. But as Marti suggested, you might want to mix something and then bring it to a calibrated dub stage to check it as well as listening to it in a few theaters.
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Derek Jones Sound Engineer / Producer / Composer Derek Jones Linkedin Megatrax Recording Studios Megatrax Studios Yelp Page A-list Music Artist Page |
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Re: Room Calibration - ATSC Standards - Help
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Mike, I think your system may not be set up correctly. If you are going AES into the Dorroughs, why are you changing any volumes? The volume knob on the 003 affects the Digital output? Digital is absolute. Levels in the DAW passed over AES are absolutely the same as what is read on a meter. Analogue is a world that needs a reference. Also, the pink noise is -20dBFS RMS, NOT Peak value. It's Peak value will be higher. You should be putting the pink in a channel that feeds the left, then adjust your monitor controller so that this pink reads your target monitoring SPL.
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Tom Hambleton CAS Ministry of Fancy Noises IMDb Undertone on Facebook Undertone Custom Sound Libraries "Groupable markers would be epochal!" -Starcrash |
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Re: Room Calibration - ATSC Standards - Help
Thanks guys, I think I've got it but needed clarification.
Tom, your right, this is a TV spec. I'm mostly mixing shorts which will or will not be shown in a theater (probably via DVD) and most definitely online. If I was in a larger room, I'd still probably hold the monitor level at around 80, just because my clients are gonna want less dynamic range and a little hotter signal. I've used the ATSC spec to calibrate, Tom your right on the pink noise, it does register higher peaks, but that's not what I'm looking at, I'm looking at a mono RMS value that sits exactly at -20dbfs per channel, which is what the paper called for and what I'm getting. Also, the 003 volume knob I'm referring to here is NOT digital. Because the 003 is meant as an all in one box for the home studio, it offers 2 headphone outputs and a volume control output to monitors. It also offers a secondary main output as well. I think it's great for convenience. But it most certainly is analog. When you guys say -27 to -31 is about right for Dx, then that makes me feel better, because that's where it feels right when I measure it on the Durrough. That ATSC speech file plays very hot, and while I understand it might be for a dub stage, I can't figure out how this is different. If say, I calibrate my monitors to 80, I hear a volume level that registers at that level. If I calibrate a dub stage to 80, that level should remain consistent. Of course more juice is being pumped through the dub's speakers to get a reading of 80 at the mix position, but never-the-less it should remain the same. So why then would the spec call for the vocal sample to be adjusted to desired level in a calibration test? I thought all measurements are supposed to got through full scale. Am i understanding you guys right? If you played this vocal file in your rooms, it would register quieter? Marti, you say I should adjust to 82, but for my room volume they say 76 is where I should stay at. I'm happy with the figure, and need to mix something and take it to a stage somewhere for a quick test. I'm up for changes, but just want to get it all right.. youknow. -mike
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Re: Room Calibration - ATSC Standards - Help
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I am confused by this statement.
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Tom Hambleton CAS Ministry of Fancy Noises IMDb Undertone on Facebook Undertone Custom Sound Libraries "Groupable markers would be epochal!" -Starcrash |
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Re: Room Calibration - ATSC Standards - Help
the Durrough is fed from the main outs of the 003, when I playback the test audio file which is supposed to read -20dbfs, I turn the volume monitor know on the 003 all the way up and leave it there. it registers -20dbfs on the durrough. The durrough is an analog meter (might not have mentioned that) reading a digital scale (top of meter is 0dbfs).
I'm now understanding that maybe I should run the durrough on the same analog chain as the monitors, but without a pass thru, I'm hesitant to duplicate the audio signal to my monitors for fear of noise. Right now I take the 1-8 analog outputs from the 003 vie db-25 cable snake to my monitor controller (brand SPL). That leaves me a main set of stereo outputs which i feed to the durrough via balanced TRS to XLR cables. The main volume is monitored and augmented via the monitor controller, the durrough is fed and augmented via the volume knob on the 003, which has been pinned at full for quite some time. any help in how to configure these all together so that the durrough reads the main monitor chain?
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Re: Room Calibration - ATSC Standards - Help
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Sorry, I am in the middle of Mixing a Film and didn't read your post correctly. listen to Minister. I gotta go.....
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Marti D. Humphrey CAS aka dr.sound www.thedubstage.com IMDB http://www.imdb.com/name/nm0401937/ Like everything in life, there are no guarantees just opportunities. |
#10
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Re: Room Calibration - ATSC Standards - Help
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Once it is analog, the level reading is an analog of the voltage. Your posts are very confusing. If you are running ANALOG, the 003 does not do -20=1.228=0vu, so you will have a problem! Forget the meter. Put the correct pink in your system and adjust the volume to the appropriate SPL.
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Tom Hambleton CAS Ministry of Fancy Noises IMDb Undertone on Facebook Undertone Custom Sound Libraries "Groupable markers would be epochal!" -Starcrash |
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