Just ordered The Traveller Blu-Ray. Hope it will arrive soon and avoid delays of the EU customs.
.... I'm experimenting with a philosophy on how to do it. For me, the goal is to make it a spacial 3D type experience without being too gimmicky or distracting. This is a challenge! Gotta be careful in my opinion. Positioning has to be well thought out as to why its there... especially with the heights because aside from ceiling reflections and jets passing by (which I do have on occasion! haha) there aren't really many things that happen up there in reality... yet surround formats can allow one to break reality and put things where they normally wouldn't be such as if the listener was standing in the middle of the band or even listening from the drummer's perspective on the drum panning (which for some reason I prefer as a listener).
Yes, it is more difficult, I think, to generate a space sensation than just moving sounds around the corners for gimmicky effects. Although some gimmicks are also welcome. For me the best thing is to combine both concepts.
Anyway, my general philosophy is to use the sides as a second expanded left and right and a way to separate things that were competing in the left and right stereo field. It can also be used as a sort of panoramic wide left and right in general.
Sides are interesting when generating the “inside the head effect”, specially with vocals. But they could overload the hearing, blocking the frontal sound, if the level is high. That happens with some Quad mixes, when the rears are directed to the sides.
I have 9.1.4 Atmos in my room, (7.1.4 + Wides). I am aware that very few users have Wides. But when an Atmos mix is made to make use of the Wides I really find more spaciality and the front stage really expands. There are several mixes that really sound exceptional to me due to the use of the Wides. Some examples are:
Harry Styles – Harry’s House – Main vocals only in Wides (instead of fronts).
Mister Moto – The J.B. Experience – Guitar on Wides, while Fronts have only a small guitar echo.
Again, I’m aware that very few people can enjoy those mixes if having only 7.1.4, as the Atmos renderer could just “move” the Wides content to the Fronts.
I always wish that the Atmos mixers use that Wide Atmos Objects location, instead of putting everything in the bed channels 7.1.2
The rears in an Atmos system are an interesting question of whether you'd do things differently there vs. a 5.1. Yes and no as some things you'd put there would be better in the sides.
I think the rears should have a great use in Atmos. They help to “locate” the sound around the complete 360º. The sounds coming from rears do not overload the hearing, as the sides can do. For me, subtle binaural sounds (including vocals) in sides, and a little more aggressive sounds in rears would be the best.
I look forward to your Atmos mixes.