Discrete 7.1 is used on Bluray. DVD tops out at 6.1.
I did not see any indication that the bipolar speakers you're thinking of would be useful for front or centre. In-ceiling is always problematic, as you have no proper control over direction. In some ways, the term bipolar is not really accurate in the context of these speakers, and the site's description of what the speakers are trying to do provides a more accurate explanation than the buzzword.
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Mark - are you saying all bluray is 7.1, or just that 7.1 is only available via bluray, but is not necessarily always available?
On the other point the mention of using the Def Tech UIW BPZ/A (or presumably the BP/A) for all 7 speakers comes from the pdf brochure here
http://www.definitivetech.com/literaturereq/prod_lit/UIWBrochure_Complete_0208.pdf. The relevant paragraph, on the first page, is this:
"
Choose Our Ultimate Performance Architectural Speakers for a Spectacular Built-in Home Theater System
In addition to bringing music into every room in your house, Definitive UIW speakers are perfect for a spectacular-sounding, high-performance home theater system. Choosing the perfect system is easy because all Definitive speakers are engineered to have the same timbral balance and sonic signature; so they can all be used together in any combination with excellent results.
The top-of-the-line signature Definitive UIW home theater system would use three matching UIW BPZ/As or UIW 75s across the front and UIW BPZ/As as rear and/or side surround speakers.
This system will sound great and deliver excellent bass without a separate subwoofer.
However, you can add any of Definitives superb powered subwoofers for even higher performance.
Remember: any combination of UIWs will work well together and deliver superior performance; so pick the ones that best suit your budget as well as your specific size, design, mounting and listening requirements."
I'm reviewing my design to see if I can in fact put my left and right surrounds onto the wall. For this to work they would have to be above the window height, at about 2.25m. With my ears being at 1.0m when seated, is this too high? Alternatively I could suspend them from the ceiling (which is 2.45m), but I think this would be a similar height. Finally, I could put the speakers on moveable mounts. This is in a way the most appealing as it means I have some flexibility, but I'm not sure how I would get them to the recommended minimum 1.8m (ie minimum 2' above listening position). Of these 2 options do you have a preference?
Thanks