Dolby Atmos® FAQ

[ssully]

What I mean is that if the 4.0 source is formatted 'into' a DTS or AC3 format (with silent channels), then the AVR will see it just as 5.1 DTS or AC3, and the DSU upmixer will work as usual for those formats.

Well, 'upmixing' from 5.1 means upmixing to more than 5 main channels, e.g., 7.1 etc. That's not what I was talking about. Formatting a 4.0 into 5.1 via silent channels does not create musical C output, because the C is already occupied...by silence, and won't create a musical C output when upmixed to 7.x either because again the C already exists , as silence.

Some AVR's or players could have restrictions to 'understand' mch if there are a weird number of channels different from 5.1. And then play it just as stereo.

My Oppo 203 does play mch 4.0 and 5.1, but cannot play 7.1. I use DUNE instead, to play mch 7.1

I think is better to 'build' mch files with a 'standard' number of channels, like 5.1. With silence in the channels with no content. Full compatibility for all systems.
Some players/AVR could not process 5.0 (a file with only five channels), for instance. 3.0 could be even more 'weird'.

Agreed, but I was/am curious to hear what the DSU upmixer does to actual 4.0 content (and 3.0 content) in a 5.x playback context.

In my system, and it may be the 'standard', in a 7.1 system, 4.0 or 5.1 files direct the rear channels to the Side Surrounds (not to the surround backs)

If I want to play Quad using the Surround Backs (rears instead of sides) in my 7.1 (without reconfiguring custom speakers assignment), I have to build a 7.1 file with silence in the sides and move the sides to the rears. It can be easily done with MMH, there is an option exactly for doing that.

HomerJAU kindly just made it a lot easier by adding a direct remix option to the lasted MMH release.

 

[ssully]

I think this is the right way, because:

- At the begining there was only 5.1 --> Quad rears go to channels 5,6
- Later, two additional surround backs were added to get 7.1 --> Quad rears still go to channels 5,6. The same. Not change to 7,8

Yes, that would seem to be the rationale of AVRs that don't output quad channels formatted as BL BR (back left, back right) when the AVR has no 'surround back' speakers connected to it, only 'surround' speakers. (The nomenclature has gotten increasingly unfortunate as time goes on :<)

I theorize that a literal way around it for 4.0 sources would be , move the connections from the 'surround' speaker inputs of the AVR to its 'surround back' inputs (and update the speaker config in the AVR menu...though I'm not even sure such a configuration is 'allowed'). But I suspect that would only work for 4.0 sources . 5.x sources would now be missing their surround output (channels 5,6).

 

[ssully]

I have installed speakers either in the ceiling or mounted them up high quite a few times when floor space was limited. I did not find the sound they produced to be all that pleasing. It is also my belief that all speaker should be matched, totally impractical with a full Atmos setup!

Speakers sound best at ear level.

Atmos height content is not mixed to be heard from 'ear level' sources. It is intended to come from above , either directly (from ceiling mounted speakers) or bounced off the ceiling to the MLP

 

[AYanguas]

I have installed speakers either in the ceiling or mounted them up high quite a few times when floor space was limited. I did not find the sound they produced to be all that pleasing. It is also my belief that all speaker should be matched, totally impractical with a full Atmos setup!

Speakers sound best at ear level.

The speakers sound good when you listen at the most centered aligned possible. That's why it is always recommended to aim each speaker directly to the MLP. Except for some rare circumstances.

With respect to the speakers at ear level, yes, it may sound better, or more 'direct', and even you may have additional immersion.

For instance, with the surround sides, locates at ear level 90º, you get such a 'binaural' effect that you can even 'feel' that the sound is coming from above. I have experienced this, and when demoing some 5.1 albums, without upmixing, the people has tell me that he likes the sound coming from above. And I told him, is not coming from above, but only from the sides. He did't believe me. It is something like the center image effect, in stereo, that you swear that the sound comes from that central speaker that you are looking at, until you get up and get closer and you see that no sound comes out of there.

The same good immersion effect is achievable with Quad, with speakers at ear level. That's why some say that it is just enough for them, because the immersion is high enough if the mix is good.

Obviously you get even more immersion effects with Full Atmos 9.1.4, but it can be debated whether that little extra effect is worth the investment.

Fortunately, there are some good Atmos mixers (believers...) that make me feel that my investment in so many speakers has been worth it

It's true that all speakers should be matched. I wouldn't say that is totally impractical with a full Atmos setup. Of course it could be impractical to hang big towers from the ceiling, and aim then down to the MLP. But medium good shelf speakers can be used for surrounds and for heights. Yes I know, its both budget and room/family/house possibilities.

 

[par4ken]

Atmos height content is not mixed to be heard from 'ear level' sources. It is intended to come from above , either directly (from ceiling mounted speakers) or bounced off the ceiling to the MLP

If that is true then why are they mixed into the "bed"? Those height sounds would be lost otherwise (without the height speakers). My point is that speakers placed up high don't really sound all that good. IIWUTM I would rather have additional channels placed around the room, than to bother with heights.

Bouncing sound off of ceilings (and walls) would give added ambience, but in stereo circles that is frowned upon as it actually blurs the intended sound image.

Edit: I was searching for information on the Toshiba QM system when I came upon this page about optimum speaker height.

 

[Sal1950]

My point is that speakers placed up high don't really sound all that good. IIWUTM I would rather have additional channels placed around the room, than to bother with heights.

That's your humble opinion, it doesn't happen to be mine or unknown numbers of Atmos enthusiasts around the world. Maybe you haven't yet heard a good system?

 

[AYanguas]

If that is true then why are they mixed into the "bed"? Those height sounds would be lost otherwise (without the height speakers). My point is that speakers placed up high don't really sound all that good. IIWUTM I would rather have additional channels placed around the room, than to bother with heights.

Bouncing sound off of ceilings (and walls) would give added ambience, but in stereo circles that is frowned upon as it actually blurs the intended sound image.

Edit: I was searching for information on the Toshiba QM system when I came upon this page about optimum speaker height.View attachment 98868

If you only have 4 speakers Quad, or 5.1, or 7.1 Then Yes. It would be better to have all speakers at ear level, if no obstacles like couch backrest, furniture or others suggest to put them a litle more above.

If you have an Atmos system, I'm afraid it would be difficult (if not impossible) to get the mixed sounds coming from above. You can have a 7.1 Atmos system, with no sounds lost, and get all the objects and bed sounds located at the ear plane level, but you will lose many of the great immersive sensation that many Atmos mixes provide, and many of us really enjoy.

 

[par4ken]

That's your humble opinion, it doesn't happen to be mine or unknown numbers of Atmos enthusiasts around the world. Maybe you haven't yet heard a good system?

I would disagree but I realise that there is no way to really experience Atmos without height speakers. But it is a fact (not just my opinion) that speakers sound best at ear level. Height is just an add on. Obviously those top mounted speakers (in the diagram) would sound better if angled downward toward the listener.

 

[ar surround]

If you only have 4 speakers Quad, or 5.1, or 7.1 Then Yes. It would be better to have all speakers at ear level, if no obstacles like couch backrest, furniture or others suggest to put them a litle more above.

My first experience with 7.1 goes back to 1989 with the Lexicon CP-1. They had some interesting ideas about the placement height of the 'extra' speakers...specifically the sides (surrounds) and rears. Lexicon believed that room width had an impact on how high these 'extra' speakers should be placed, and their analysis seems like a harbinger of the Atmos concept:

Lastly, I just have to rub it in about Lexicon suggesting that there be no center channel speaker when it comes to setups for music vs. film.

 

[LB-V]

Lastly, I just have to rub it in about Lexicon suggesting that there be no center channel speaker when it comes to setups for music vs. film.

 

[ssully]

If that is true then why are they mixed into the "bed"?

Because Dolby is all about back-compatibility. But Dolby doesn't promise that a bed mix will sound the same as the full Atmos layout mix. Obviously it won't recreate the height information/sensation the mixing engineer intended in those channels. It will do 'something else', hopefully pleasing.

The Atmos mix is mixed in a studio with an Atmos speaker setup , including height speakers. I don't know if the bed mix is 'auditioned' separately before release to make sure it sounds good. I would hope so.

Those height sounds would be lost otherwise (without the height speakers). My point is that speakers placed up high don't really sound all that good. IIWUTM I would rather have additional channels placed around the room, than to bother with heights.

Sound only coming from up high maybe 'don't sound all that good'. But the height channels for Atmos aren't meant to be the only channels the listener hears. They are a contribution to the 3-dimensional sound field.

 

[LuvMyQuad]

I would disagree but I realise that there is no way to really experience Atmos without height speakers. But it is a fact (not just my opinion) that speakers sound best at ear level. Height is just an add on. Obviously those top mounted speakers (in the diagram) would sound better if angled downward toward the listener.

But isn't this a function of the speaker design? Sure, floorstanders sound best at ear level. They are designed to do that. Typical in-ceiling Atmos height speakers are not designed to sound best at ear level. They are designed to cover a defined area and dispersion angle, and in many cases are aimable to the sweet spot to achieve that. I doubt they would sound any better at ear level. Inherently they are much smaller than most floorstanders mains.

 

[par4ken]

But isn't this a function of the speaker design? Sure, floorstanders sound best at ear level. They are designed to do that. Typical in-ceiling Atmos height speakers are not designed to sound best at ear level. They are designed to cover a defined area and dispersion angle, and in many cases are aimable to the sweet spot to achieve that. I doubt they would sound any better at ear level. Inherently they are much smaller than most floorstanders mains.

I think that it is a function of the design of our ears. The ears filter sounds from above and below to enable our brains to discern up and down or else we would need a couple of more ears! There is obviously nothing that can be done about that! It is just a fact that we hear things better head on and to the sides.

One reason that I like to place my Quad back speakers more out to the sides rather than behind is that when placed like that they act more like headphones and even produce the illusion of height. The sound reaches the ear more head on! I suspect that much of the Stereo only Audiophile rejection of surround is because speakers placed behind you do not sound as good as they do when placed up front.

 

[ssully]

Our knowledge has advanced since the quad era. 5.1 layouts typically recommend an angle of from 10 to 30 degrees to the rear of the listener, for the two 'surround' speakers...not very far 'back', really. 7.1 layouts add actual 'back' speakers.

0 degrees really is like 'headphones' and for me, that would definitely require rebalancing levels so they didn't overpower the front stage.

But we get to do whatever sounds good to us.

 

[marpow]

I think that it is a function of the design of our ears. The ears filter sounds from above and below to enable our brains to discern up and down or else we would need a couple of more ears!

I agree with this.
Not all the time, most of the time I just go willy/nilly bouncing around to different recordings.
But, if I want to have a serious ATMOS listening session, this needs time, comfort and lack of distraction, no tapping on the internet.
I will start off with stereo, then 5.1 (no need for 4.0) then ATMOS, this is a real good pre workout to engage my body, mind and listening skills.

In a couple of weeks when I go see U2 at The Sphere in Las Vegas with their 160 thousand speakers, what the heck am I going to do?

 

[AYanguas]

I think that it is a function of the design of our ears. The ears filter sounds from above and below to enable our brains to discern up and down or else we would need a couple of more ears! There is obviously nothing that can be done about that! It is just a fact that we hear things better head on and to the sides.

One reason that I like to place my Quad back speakers more out to the sides rather than behind is that when placed like that they act more like headphones and even produce the illusion of height. The sound reaches the ear more head on! I suspect that much of the Stereo only Audiophile rejection of surround is because speakers placed behind you do not sound as good as they do when placed up front.

Yesss. This is the right explanation for me.

The speakers sound the same, wherever they are located. There is an Optimum difussion angle under what we perceive full equalized frequencies.

If the speakers are aligned towards our head, we are in the Optimum location to perceived the full eq sound.

But we, humans, hear different a sound coming from the front, or the rear, or above.

The Atmos system tries to simulate real world. In the real world sounds are coming from above, as from the ceiling speakers. We perceive that above sound more difussed, but then if you move your head looking at the ceiling, because there is an interesting Atmos sound there, you notice immediately that "the ceiling speaker sounds better". Because It is as if it were at "ear" level. The same as in the real world. A real aeroplane sound difussed , then you look at the sky and the plane sound is much better and you are able to locate it.

I'm just listening Dolby Atmos Luminescence Bruce Soord, looking at the ceiling. Yesss, my ceiling speakers sound better... No, I hear better. Wonderful Bruce Soord immersive vocals all around, wides and above. It really looks that Bruce has listened to our complaints of that binaural vocals , only from the sides, that he mixed on the pineapple thief studio concert.

You look above at the ceiling and the Bruce vocals falls gently over you. Wonderful

 

[AYanguas]

You look above at the ceiling and the Bruce vocals falls gently over you. Wonderful

Lets move our head, to exercise the neck, when listening Dolby Atmos.

Without shame, like when someone is surprised for the first time and looks in all directions, to locate the sounds.

And suprisingly... the speakers seem to sound better.

 

[Sal1950]

Lets move our head, to exercise the neck, when listening Dolby Atmos.

Without shame, like when someone is surprised for the first time and looks in all directions, to locate the sounds.

And suprisingly... the speakers seem to sound better.

An exercise in visual bias ?
Yep it's a real thing
The big reason for blind listening tests.

 

[par4ken]

An exercise in visual bias ?
Yep it's a real thing
The big reason for blind listening tests.

Oh come on, such rubbish!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

[mandrix]

I have all 11 speakers pointed directly at the listening position, that includes the 4 height speakers.
My height speakers are indeed smaller than my 7 ear level placed speakers. But they are not tiny speakers, IMO. They have 5.25 inch woofers and seem adequate for their intended use, and have a frequency response claimed as 63-24KHz and rated up to 100W. (had to Google that, CRS you know). They can be bi amped, though I hardly see the need.
The 4 height speakers are identical.

The other 7 speakers are placed at, or close to, ear level. The "corners" are a matched set.
Rear surrounds are at about 90*, and the Surround back speakers behind and aimed at a steeper angle. Even for Quad listening, I'm just used to it now but since the bulk of my listening is Atmos I appreciate the way I have things set up.

I would not say I have the best or most expensive speakers available. But I bought what i could afford...doesn't everyone?

If you have not listened to a well set up Atmos system with proper room correction and don't see a need to then it's your loss, or if you're just happy with what you got, that's the name of the game.
But to state that all speakers MUST be at ear level is just a little shortsighted IMO, and takes away from the immersive sound experience of Atmos.