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Dolby Atmos deeper tech questions

puntloos

Member
So this week I moved from "3½.1.0" (2 great front speakers, 2 terrible rear speakers, great subwoofer) to 7.2.0 where my surrounds are prosumer quality. Audyssey MultEQ done.. and now.. WOW. I have already achieved what I hoped for which is a true cinema-level quality. (ok maybe not full IMAX ;) )

I do have a bunch of atmos questions that I couldn't find in the common sources (incl the AVForums Guide). More sources very welcomed!

1/ How do Atmos receivers handle standard 5.1 sources? Will the extra speakers (sides, heights) do anything, or will just 5.1 be active?

2/ what's the perfect height of surround speakers? Exact ear level? Slightly above? Sadly ear level is a bit awkward since it means people will often brush past these speakers when moving through my room.

3/ Does atmos/audyssey drive 2 subwoofers separately?

4/ As I understand atmos, object audio means that the 'data stream' literally contains the object "sound" and location information (e.g. object1: "yeah!",x,y,zlocation - object 2: "[email protected]£,x,y,z, object3: "trumpet1:honk",xyz). Is that correct?

5/ Related to #4, I see some sources tagged as "7.1" - e.g. This Google Search "Atmos 7.1 Demo" - turns up a ton. Do these miss the 'height' information, or would it be better described as "Atmos Demo" since every object simply contains xyz data?

6/ How does atmos 'play together' with TrueHD? Is there some good conversion? I think TrueHD is still channel based, so the system will just do it that way?

7/ How does atmos work together with the THX spec? (THX, as I understand it, is mostly a specification of what the ideal physical setup is.. speaker location, quality, volume level capabilities).. but is a THX system by definition also fine with Atmos and vice versa? Or ?

8/ Audyssey has a Midrange Compensation function. Does Atmos like this?

9/ Auro3D and other formats: I guess Atmos has already 'won', but it seems to me that there might be new technologies that might be helpful to keep an eye on - would it make sense to design your home (incl preparing cabling..) to be ready for these systems too? I'm debating wiring up my room - while I still have the chance - to accommodate multiple extra 'rings' of speakers, especially at floor level too . Is that crazy?

10/ Is there any suggested way to measure how accurate your Atmos system reproduces the sound that the engineers intended?

Phew, that's it for now =)
 

gibbsy

Moderator
1/ How do Atmos receivers handle standard 5.1 sources? Will the extra speakers (sides, heights) do anything, or will just 5.1 be active?
All Atmos capable receivers come with the upmixing modes of Dolby Surround and DTS Neural. This will upmix and bring in the Atmos domain speakers. DTS Neural is very effective especially on DTS HD material.
2/ what's the perfect height of surround speakers? Exact ear level? Slightly above? Sadly ear level is a bit awkward since it means people will often brush past these speakers when moving through my room.
Dolby now state at a seated head height. In reality almost every room with the exception of a dedicated cinema room will have to live with some kind of compromise, but essentially the lower the better.
3/ Does atmos/audyssey drive 2 subwoofers separately?
No there is a single LFE output, the two connected subs will act as mono. Two are better than one as it will help with nulls in the room.
4/ As I understand atmos, object audio means that the 'data stream' literally contains the object "sound" and location information (e.g. object1: "yeah!",x,y,zlocation - object 2: "[email protected]£,x,y,z, object3: "trumpet1:honk",xyz). Is that correct?
Atmos is contained as metadata within the Dolby TrueHD audio and the receiver will decode it and place objects where the director intended.
6/ How does atmos 'play together' with TrueHD? Is there some good conversion? I think TrueHD is still channel based, so the system will just do it that way?
It's additional to TrueHD and is basically answered above.
7/ How does atmos work together with the THX spec? (THX, as I understand it, is mostly a specification of what the ideal physical setup is.. speaker location, quality, volume level capabilities).. but is a THX system by definition also fine with Atmos and vice versa? Or ?
THX has been somewhat overtaken by the new audio formats but studios still mix to reference level, usually 75dB.


Others can answer the rest, I'm exhausted.
 

doug56hl

Distinguished Member
So this week I moved from "3½.1.0" (2 great front speakers, 2 terrible rear speakers, great subwoofer) to 7.2.0 where my surrounds are prosumer quality. Audyssey MultEQ done.. and now.. WOW. I have already achieved what I hoped for which is a true cinema-level quality. (ok maybe not full IMAX ;) )

I do have a bunch of atmos questions that I couldn't find in the common sources (incl the AVForums Guide). More sources very welcomed!

8/ Audyssey has a Midrange Compensation function. Does Atmos like this?
Atmos isn't bothered by it. It's just a dip in output level around 2K Hz. You can turn it off using the Multi Eq Editor app (£20).
10/ Is there any suggested way to measure how accurate your Atmos system reproduces the sound that the engineers intended?
Your ears? Try them in combination with the Atmos demos. Dolby Trailers - ATMOS, Lossless TrueHD 7.1, AC3 5.1 You want the ones which show lossless atmos.
 
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