Baffle wall info:
What is a THX baffle wall and why do I want one in my home theater?! This article explains what a baffle wall is, covers the acoustic and audio benefits and finally provides tips on how to design and build them. A baffle wall is essentially a false wall into which the screen speakers (i.e. left...
www.acousticfrontiers.com
I just used two layers of 18mm MDF and everything was screwed together so it could be easily removed when I move house. Otherwise I would have used a layer of plasterboard and Green Glue as well. 1" of Linacoustic is recommended for the baffle wall over in the US, but I found 40mm Acoustic foam has similar NRC values and used that instead.
You can angle the left and right speakers along with the left and right sides of the baffle wall if necessary. I'd recommend compression drivers with waveguides as they direct the audio towards the audience more than the walls, floor and ceiling, and have a more cinematic sound (IMHO) as that's what commercial theatres use. If you're on a budget, some Behringer B215XL speakers work very well, and go down to about 40hz in a baffle wall. There's a long thread over on avs if you're interested.
If you're into DIY, you can build a simple screen frame and stretch/staple the screen material over it. The cheapest AT material is Spandex, with a layer of white over black. There is a new AT material from XY screens (weave, not perf) that is said to be excellent and although more expensive than Spandex, represents good value. Have a read here and over on avs for more info. I think this is the stuff:
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Otherwise, Seymour XD and UF materials get good reviews, though with XD the weave can be seen by some people from 11ft or closer, whereas UF is fine down to around 6ft.
There are various guidelines for 'optimum' immersion viewing distances, and a good rule of thumb is to sit around the same distance from the (scope) screen as the screen is wide (that gives approx a 50 degree horizontal viewing angle for scope, and 40 degrees for 1.85). Experiment with that as a starting guide. Another rule of thumb for that is to sit around 2.4 x the screen height back from the scope screen. They're just guides but that's not unlike sitting midway in the seats in a commercial theatre.
You can use a simple online right angle triangle calculator to work out the angle from your (seated) eyes to the top of the screen - ideally no more than 15 degrees is recommended or neck ache can set it after a while. 35 degrees is the absolute limit.