Dolby Atmos ceiling speaker orientation

[Kosta]

I am doing some research on Dolby Atmos speaker placement and I am a bit confused with dolby's layouts. According to them (or as far as I understand), they only recommend downfiring inceiling/full range speakers in front and behind the viewer in 5.1.4 setups. I have also seeing various layouts in different sites though recommending full range speakers placed at 45 degrees in front, behind and facing the viewer. What is the correct speaker placement?

Finally, would 2 downfiring ceiling speakers directly above the viewer be enough for Atmos or are 4 speakers the minimum for the full atmos experience? From what I hear you only need more atmos speakers if you have more than 1 row of seats and I will only have one couch.

 

[William Lemmerhirt]

I am a little confused by your descriptions. Seems like they both are talking about similar locations.
In any case, .2 Atmos can be ok with the height speakers just in front of the viewer(on/in the ceiling). Atmos also supports “height” locations on the front and back wall where the ceiling meets the wall.
.4 Atmos IS better than .2 and .2 is very difficult to be effective with multiple rows.
Here’s some reading that might help.

https://professional.dolby.com/siteassets/tv/home/dolby-atmos/atmos-installation-guidelines-121318_r3.1.pdf

https://professional.dolby.com/siteassets/tv/home/dolby-atmos/dolby-atmos-for-home-theater.pdf

 

[Kosta]

I found what I was looking for in the second pdf and now I understand why my description was confusing.

Dolby recommends either wide dispersion speakers (over 45 degrees) If you are planning on placing them facing downwards (meaning facing the floor) or angle narrow dispersion speakers towards the listening position. so angling them is allowed in an Atmos setup.

They don't mention a specific angle though, they just say "angle slightly". Should I be aiming for a sweet spot based on the tweeter's dispersion or is the logic between height and front speakers sweetspot placement different. Like the bipolars for example that are not meant to give you an accurate representation of the exact direction of sound behind you, are the height speakers meant to be directional or just give you a similar feeling to bipolars/dipolars?

The reason I am asking that is because if I can calculate the right angle, I can order some custom made speakers, with the drivers placed at the correct angle and simply place them at the right distance on the ceiling. That way I can skip the guesswork.

 

[William Lemmerhirt]

I found what I was looking for in the second pdf and now I understand why my description was confusing.

Dolby recommends either wide dispersion speakers (over 45 degrees) If you are planning on placing them facing downwards (meaning facing the floor) or angle narrow dispersion speakers towards the listening position. so angling them is allowed in an Atmos setup.

They don't mention a specific angle though, they just say "angle slightly". Should I be aiming for a sweet spot based on the tweeter's dispersion or is the logic between height and front speakers sweetspot placement different. Like the bipolars for example that are not meant to give you an accurate representation of the exact direction of sound behind you, are the height speakers meant to be directional or just give you a similar feeling to bipolars/dipolars?

The reason I am asking that is because if I can calculate the right angle, I can order some custom made speakers, with the drivers placed at the correct angle and simply place them at the right distance on the ceiling. That way I can skip the guesswork.

Depends somewhat on how many rows/seats and ceiling height. Height/top speakers should always be monopole. They’re purpose is to provide sounds from the height layer, yes, but also to phantom image in XYZ coordinates ether bed layer into the room(objects). So if you have only one or two seats, as usual on axis placement will be better. If you have a bunch of seats then you might want to split the difference a little bit. Ceiling height is important here too. Higher ceilings will make it easier to provide wider coverage and avoid hot spotting.
Personally I only have one seat that’s really important and if I have guests, then I just give that up.

 

[Kosta]

Depends somewhat on how many rows/seats and ceiling height. Height/top speakers should always be monopole. They’re purpose is to provide sounds from the height layer, yes, but also to phantom image in XYZ coordinates ether bed layer into the room(objects). So if you have only one or two seats, as usual on axis placement will be better. If you have a bunch of seats then you might want to split the difference a little bit. Ceiling height is important here too. Higher ceilings will make it easier to provide wider coverage and avoid hot spotting.
Personally I only have one seat that’s really important and if I have guests, then I just give that up.

I will only have 1 row plus my ceiling is quite high (about 12 feet) so it should be quite easy to create a sweetspot.

Your replies were very helpful and informative! Thank you!

 

[William Lemmerhirt]

I will only have 1 row plus my ceiling is quite high (about 12 feet) so it should be quite easy to create a sweetspot.

Your replies were very helpful and informative! Thank you!

Any time! In retrospect I’d liked to have taken a little more time to address your questions, but I was driving around on my forklift and spent the day in my truck!
As long as you found what you were looking for. It’s all good.