Originally Posted by bargervais
I was always under the impression that the front three are the most crucial and do most of the work is that correct
While I cannot speak to height channels one way or another in the context of Atmos or anything else (never heard, let alone used, heights) for 2 to 7 channel systems I think that's right. Ideally, the front three speakers should be identical speakers oriented identically and at the same height. When that is not practicable then one should try to get as close to the ideal situation as possible. The rest of 'em...basically, make sure they're placed right and aren't terrible performers.
Originally Posted by NorthSky
Best surround sound experience comes from identical loudspeakers ALL AROUND. ...Front Left, Center, FR, SR, and SL.
I don't think that's particularly or at all important, actually. LCR, yes. The rest of 'em, not so much. At least on material for which fidelity is an actual issue, such as orchestral concerts recorded in multichannel. For movies, whatever. Don't know, don't care.
Originally Posted by David Susilo
Once you've experienced surround with 100% identical speakers, you will then realize how important having identical speakers all around.
Except when you've done it, and realized that after spending an awful lot of money on four speakers to your sides or rear you're not even positive you could tell the new 20x more expensive surrounds from the old ones in a blind test, even though when you compare them as main speakers the spectral balance, image rendition, and dynamic reproduction of the new ones are all beyond question superior...
Furthermore, there's a strong case to be made that ambience speakers have different requirements from front-stage speakers, especially in a small room.* Dr. Toole touches on this idea in Sound Reproduction.
Note that his discussion of surrounds never once refers to mains.
Instead, he refers to problems unique to the surround channels in small rooms, such as localization at one surround speaker for listeners outside the main listening position, and makes some proposals that seem to have intuitive merit but are not widely adopted, such as use of line or CBT arrays for ambience channels.
I don't see how Atmos would change the equation there, though I'm very open to changing my mind if presented with a good argument.
*"Small room" used here as a term of art to refer to the kinds of spaces found in personal homes, as distinct from "large rooms" such as auditoria or concert halls that seat hundreds or thousands of people.