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Why do cinema and music Dolby Atmos layouts differ?

Dj7675

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I realise that, however, if you look at the pictures you will see that recording studios do the opposite, hence my post. Especially look at the the first picture on my post, the blue room. The height speakers are almost on top of the side surrounds. In your suggestion, which I agree and, which Dolby guides agree the height speakers should be nearer to the centre, hence increasing the angle between the surround and them.
The studio install guidlines are fairly new. I'm not sure when that room was installed or designed. I'm no expert but that room would have too little seperation IMO from the surrounds and heights. If they follow the Dolby studio guide the atmos speakers would be much more on top of the listeners. I wouldn't pay much attention to pictures of rooms that aren't following current dolby guidlines. I think you can find just as many examples that follow the current studio guidlines as well. Also, many that design rooms for a living such as Anthony Grimani also have their top/height speakers much more on top of listeners than you see in the Dolby Home Guidlines as well.
Another way to think about it... all the pairs of speakers need to be able to create a stereo image between them... If they can't, then then are too far apart or you need another pair of speakers to fill the gap. For example if you follow the home guide on and with a 30degree for front height and 30 degree rear height (no middle speakers) there is no way you are getting a stereo image overhead. You will get a dead spot overhead IME.
 
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sarumbear

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Another way to think about it... all the pairs of speakers need to be able to create a stereo image between them... If they can't, then then are too far apart or you need another pair of speakers to fill the gap. For example if you follow the home guide on and with a 30degree for front height and 30 degree rear height (no middle speakers) there is no way you are getting a stereo image overhead. You will get a dead spot overhead IME.
I do realise that hence my question was why so many expensive rooms are not following the logic & guides?
 

Dj7675

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I realise that, however, if you look at the pictures you will see that recording studios do the opposite, hence my post. Especially look at the the first picture on my post, the blue room. The height speakers are almost on top of the side surrounds. In your suggestion, which I agree and, which Dolby guides agree the height speakers should be nearer to the centre, hence increasing the angle between the surround and them.
The current Dolby Studio Guidlines appear to have been released May 6, 2021. I am just guessing that those rooms were designed/built prior to that.
 
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sarumbear

sarumbear

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The current Dolby Studio Guidlines appear to have been released May 6, 2021. I am just guessing that those rooms were designed/built prior to that.
The earliest capture by the WayBack machine is dated 20 July 2020, more than two years ago.


However, the more I study the more I realise that like in most things in audio, nobody knows what they are doing. Competing standards are also not helping.
 

Dj7675

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The earliest capture by the WayBack machine is dated 20 July 2020, more than two years ago.


However, the more I study the more I realise that like in most things in audio, nobody knows what they are doing. Competing standards are also not helping.
I tried to look at the lookback machine link and it didn't appear to be linking to the same document I provided (dolby studio guidlines).
 
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sarumbear

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I tried to look at the lookback machine link and it didn't appear to be linking to the same document I provided (dolby studio guidlines).
Wayback Machine only stores page/post URLs not files.
 

Dal1as

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Watch the video that was posted. Dolby atmos is angle derived but relies on the sound from each speaker needing to be equal distant apart. I moved my heights farther in after researching this and seeing that video and the difference was huge. There is a thread on this over at AVS forums where the video author further explains all this.

I also remember a friend/professor who was showing me their dolby lab explaining this. I remember him stating since dolby atmos relies on (point source placement?) Of sound it's optimal for every speaker to be equal distant with the same phantom spread between every pair. No matter if you go side to side or up and down.
 

charleski

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I realise that, however, if you look at the pictures you will see that recording studios do the opposite, hence my post. Especially look at the the first picture on my post, the blue room. The height speakers are almost on top of the side surrounds. In your suggestion, which I agree and, which Dolby guides agree the height speakers should be nearer to the centre, hence increasing the angle between the surround and them.
The blue room seems to have the speakers at around a 30degree angle to the ear plane, which is on the limit of the Dolby recommendation. I suspect they'd installed the fancy circular ceiling rack and then just had to use that for the speakers. The blackbird room with the landscape diffusers shows height speakers almost bang-on 45degrees, which is probably a better placement. I think it all comes down to whatever location fits the angle and distance requirements given the size and shape of your room. Since most domestic living rooms are relatively wider the heights end up inside the surrounds, but that's just a function of the room shape.
 
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sarumbear

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Watch the video that was posted. Dolby atmos is angle derived but relies on the sound from each speaker needing to be equal distant apart.
What you say is correct and both images I posted above fails those required those angles. Not to mention that the video doesn't explain my question, does it?
 
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sarumbear

sarumbear

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The blue room seems to have the speakers at around a 30degree angle to the ear plane, which is on the limit of the Dolby recommendation.
The limit is minimum 45 degrees plus the side surround elevation. The 30 degree limit you mention is side view. See both charts below from "Dolby Atmos Home Entertainment Studio - Technical Guidelines," which was linked earlier in the thread.

1669810776336.png

1669811024541.png
 
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sarumbear

sarumbear

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Then the blue room you show is set up wrong.
Now you may understand why I'm asking the question. The blue room is the headline image on the Dolby website where the layouts are described...
 

charleski

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Now you may understand why I'm asking the question. The blue room is the headline image on the Dolby website where the layouts are described...
Well, I think we're seeing the difference between engineers and salesmen here :). I suspect that whoever designed the website just chose the image they thought most impressive.
 

Cbdb2

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Dolby surround, AC-3, Atmos, DTS, SDDS, where all developed for film in theatres. This is what I think of when some one says Atmos mix room.


This would be a smaller one.
These rooms need to work for all the formats.
Using these formats at home is always a compromise.
 

Cbdb2

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Since its most practical to put your surrounds on the walls, Dolby knows this, the ceiling speakers have to go inside.
 
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sarumbear

sarumbear

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Dolby surround, AC-3, Atmos, DTS, SDDS, where all developed for film in theatres. This is what I think of when some one says Atmos mix room.


This would be a smaller one.
These rooms need to work for all the formats.
Using these formats at home is always a compromise.
The subject is why professional studios do not follow the Dolby specifications. Besides, Dolby has separate specifications for cinema and home audio. They don’t want professionals to compromise, why should I?

I have a custom designed HT like many people. Dolby Atmos is distributed on home media for consumers to enjoy.
 

DavidMcRoy

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The subject is why professional studios do not follow the Dolby specifications. Besides, Dolby has separate specifications for cinema and home audio. They don’t want professionals to compromise, why should I?

I have a custom designed HT like many people. Dolby Atmos is distributed on home media for consumers to enjoy.
I think the only thing one can do is to follow Dolby Labs' recommendations. The directions are unambiguous, whereas photos shot from random angles with wide angle lenses are not. Nothing can be done about how a control room was set up, except by the studio owner.
 
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