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post #1 of 16 Old 12-22-2013, 12:36 AM - Thread Starter
 
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I'm not very clued up when it comes to this. Recordings whether music or movies produces dbs at least 15-20 db higher than the desired level, ie. if processor is at 75db the spl during playback is 15-20 dbs higher.

 

According to THX standards 85db is where you wanna be playing at to hear what the engineers were intending to be heard and you need enough headroom to accomodate 15-20 dbs to accommodate the dynamic range in the recording. So if you set volume at 80db during playback you are at 95-100 db.

 

Most systems may not be strong enough to still give +-20 db headroom at this level. Is this inconsistency between pink noise and playback unique to my system?

 

What does this mean in the real world? I'm asking this because most systems listened to at 75-80db as per the volume reading May be playing at a much higher level than the owner think it is. If this is the case this will lead to clipping and damage to the ears and gear during those peak levels during playback as the system is probably pushed to way beyond 100db.

 

What do you guys think about this?

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post #2 of 16 Old 12-22-2013, 12:50 AM
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Music has no reference; movies do. Movies are recorded at -20dBFS (85dB) with 20dB of peaks. So, all the speakers can go as high as 105dB during peaks. LFE track is played back 10dB louder than the rest of the speakers, so, subwoofer hits 115dB peaks. You add another 5dB for redirected bass and your sub should be able to play back peaks close to or in access of 120dB.

However, there are few subs that can hit those peaks without teaming up with multiple subs. As to the listening preferences; nobody is telling you to watch movies at reference volume. Coz speakers and audio equipments can be replaced; but not the ear drums.

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post #3 of 16 Old 12-22-2013, 01:37 AM
 
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Originally Posted by braveheart123 View Post

Music has no reference; movies do. Movies are recorded at -20dBFS (85dB) with 20dB of peaks. So, all the speakers can go as high as 105dB during peaks. LFE track is played back 10dB louder than the rest of the speakers, so, subwoofer hits 115dB peaks. You add another 5dB for redirected bass and your sub should be able to play back peaks close to or in access of 120dB.

However, there are few subs that can hit those peaks without teaming up with multiple subs. As to the listening preferences; nobody is telling you to watch movies at reference volume. Coz speakers and audio equipments can be replaced; but not the ear drums.

Must the levels be set to 75 dB or 85 dB? THX I think recommends 85 dB. Other places recommend 75.
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post #4 of 16 Old 12-22-2013, 02:29 AM
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Originally Posted by braveheart123 View Post

Music has no reference; movies do. Movies are recorded at -20dBFS (85dB) with 20dB of peaks. So, all the speakers can go as high as 105dB during peaks. LFE track is played back 10dB louder than the rest of the speakers, so, subwoofer hits 115dB peaks. You add another 5dB for redirected bass and your sub should be able to play back peaks close to or in access of 120dB.

However, there are few subs that can hit those peaks without teaming up with multiple subs. As to the listening preferences; nobody is telling you to watch movies at reference volume. Coz speakers and audio equipments can be replaced; but not the ear drums.

Braveheart statement about damaging your hearing is very important. Most people do not watch movies at reference level in there homes. The vast majority of systems that people have may not meet THX standard but, that does not mean it is a bad system and not enjoyable. Sometime to much emphasis is place on how loud a system goes or how low the sub goes as the gold standard

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post #5 of 16 Old 12-22-2013, 02:33 AM
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Do not confuse calibration level with playback level. The test tones in AVRs are recorded at -30dBFS (75dB). That is so coz 85dB test tones are extremely loud and may cause damage to ears. 75dB is a safe playback level.

So when you level match all your speakers to 75dB using internal test tones of AVR, you will still hear movies at 85dB coz they are recorded at -20dBFS (85dB) at the reference volume. 00 on master volume is easy to remember; you can calibrate your system to 75dB at -13 or any other number on master volume. But it is not easy to remember.

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post #6 of 16 Old 12-22-2013, 02:41 AM
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There is a very fine line between loudness and noise. If I watch an action packed movie at movie reference volume for more than 10 minutes, I lose the perceived loudness and for me that turns into noise. I am not able to discern between different sounds especially in the lower 2 octaves.

IMO the best playback level beyond which one must not go is the threshold where cranking the volume more turns into noise. Now this is pure subjective and YMMV. My reference max is 75dB and normal listening is around 65dB.

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post #7 of 16 Old 12-22-2013, 03:18 AM
 
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So when you level match all your speakers to 75dB using internal test tones of AVR, you will still hear movies at 85dB coz they are recorded at -20dBFS (85dB) at the reference volume.

So movies are recorded at -20 dBFS and the calibrated levels in the home are 75 dB? But I thought pink noise in AVR's were recorded at -30. So wouldn't the level be 75 dB? Perhaps you could explain.
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post #8 of 16 Old 12-22-2013, 03:27 AM
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Originally Posted by Heinrich S View Post

So movies are recorded at -20 dBFS and the calibrated levels in the home are 75 dB? But I thought pink noise in AVR's were recorded at -30. So wouldn't the level be 75 dB? Perhaps you could explain.

Pink noise in AVRs are indeed recorded at -30dBFS for the reason I mentioned earlier. Let's say you calibrate your system to 75dB at 00 on master volume. Now if you play a content recorded at -40dBFS (65dB), it will play at 65dB when the master volume is 00 i.e. 10dB lower than what you calibrated coz internal test tones of avr are recorded at -30dBFS (75dB).

OTH content recorded at -20dBFS will play back at 85dB when the master volume is on 00 i.e. 10dB hotter than what you calibrated at coz the content itself is recorded at 10dB higher level.

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post #9 of 16 Old 12-22-2013, 03:38 AM
 
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OTH content recorded at -20dBFS will play back at 85dB when the master volume is on 00 i.e. 10dB hotter than what you calibrated at coz the content itself is recorded at 10dB higher level.

I assumed there was a standardized volume for movie soundtracks. The average level can't be below 75 dB if you use 0 as your reference volume. But the max can only be 105 as you can't exceed 0 dBFS. So what you are saying is that if you set up your system to 75 dB at 0, then at 0, the playback SPL could be 85 dB if the recorded content was at -20 dBFS.

Just sounds so confusing to me.
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post #10 of 16 Old 12-22-2013, 03:47 AM
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I assumed there was a standardized volume for movie soundtracks.

Assumption is the mother of all the FUs. Yes movies do follow playback level NOT the volume level. You can choose any volume as long as your entire system is calibrated to pump out 85dB at that reference point on the volume dial during movies playback.

Speakers' sensitivity, listening distance, and room acoustics all come into play when calibrating your system to movie reference level.

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post #11 of 16 Old 12-22-2013, 03:51 AM
 
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Assumption is the mother of all the FUs. Yes movies do follow playback level NOT the volume level.

I find there is a pretty huge disparity in playback level from one film to another, at a fixed master volume. So a movie like the Matrix at -10 from reference is more than tolerable, but other films at -10 are much, much louder.
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You can choose any volume as long as your entire system is calibrated to pump out 85dB at that reference point on the volume dial during movies playback.

You mean 75 dB? If I use my receivers test tones I should calibrate to 75 dB not 85 dB.
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post #12 of 16 Old 12-22-2013, 03:56 AM
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You mean 75 dB? If I use my receivers test tones I should calibrate to 75 dB not 85 dB.

Yes. But the actual movie playback will be 85dB at reference volume. Why? Because the content is recorded 10dB louder than the AVR's internal test tones.
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I find there is a pretty huge disparity in playback level from one film to another, at a fixed volume.

You are right. Certain movies are recorded at higher levels and some at lower. For example Taken, The Conjuring, MI-4 GP are some of the movies that have exaggerated LFE track.

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post #13 of 16 Old 12-22-2013, 04:14 AM
 
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Originally Posted by braveheart123 View Post

Yes. But the actual movie playback will be 85dB at reference volume. Why? Because the content is recorded 10dB louder than the AVR's internal test tones.

If that's the case then what's the point of calibrating to 75 dB? If movie soundtracks are recorded at levels higher than the calibrated levels using pink noise, it just seems like there is no standard. It's just all over the place.
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post #14 of 16 Old 12-22-2013, 04:19 AM
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That's because pink noise is very displeasing to ears. Just download a speakers level pink noise recorded at 85dB and play it. You would know why AVRs have 75dB PN

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post #15 of 16 Old 12-23-2013, 10:42 AM
 
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Thanks for the replies braveheart. So reference level calibration only affects content like Dolby digital and DTS. It holds no significance for other media sources. Like satellite or CD?

So what I'm understanding now is that the 75 dB calibration level is the calibration level for the pink noise only. It has nothing to do with the playback level of the movie at reference. So the engineer could make the film -50 dBFS at reference or -40 dBFS or 0dBFS at a particular moment in the film. Reference level is just a calibration, it is not an SPL for movie soundtracks, that's what the engineer decides. Reference level just allows you to experience what the filmmaker heard in the studio.
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post #16 of 16 Old 12-23-2013, 11:05 AM
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So reference level calibration only affects content like Dolby digital and DTS. It holds no significance for other media sources. Like satellite or CD?

Correct.
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So what I'm understanding now is that the 75 dB calibration level is the calibration level for the pink noise only. It has nothing to do with the playback level of the movie at reference.

Correct; but when you calibrate your system with AVR internal test tones (which are recorded at -30dBFS) to a reference volume i.e. 00 on reference scale master volume, then 00 master volume during movies playback is 85dB coz movies are recorded at -20dBFS, which is 10dB louder than the internal test tones of AVR.
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So the engineer could make the film -50 dBFS at reference or -40 dBFS or 0dBFS at a particular moment in the film. Reference level is just a calibration, it is not an SPL for movie soundtracks, that's what the engineer decides. Reference level just allows you to experience what the filmmaker heard in the studio.

Think of it like interstate highway speed limits in US. It's 75 mph. Now it doesn't mean you have to do 75 mph all the time. 75 mph is the max sustained speed limit on which you won't get a ticket. Although, you can go up till about 85 mph for may be a very short period of time and state trooper won't book you.

Now think of it as 85dB in movies is equal to 75 mph speed on interstate highway. For short bursts; 105dB in movies is 85 mph speed on interstate.

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