Ceci ne concerne pas directement Audyssey DSX, mais permet de se faire une idée sur l'impact de 2 canaux arrières vs 1 canal arrière.
sur AVS, Jeremy Anderson a écrit:Yes, but 7.1 in the home is meant to address psychoacoustic reversal issues caused by single point sources placed directly behind the head in close proximity in a 6.1 setup... and there are a ton of movies mixed for 5.1 EX, even if they aren't flagged as such. 7.1 is the only way to properly reproduce a 5.1 EX mix in a home theater space, which is why Dolby recommends using DPL-IIx to process EX material in 7.1 setups.
My point here is that there's a difference between theatrical and home theater spaces, and the number of speakers required to achieve the same effect in the home. With the surround arrays in a 5.1 EX theater, the only way you can recreate that at home is with 4 surrounds. Strict 5.1 in the home would depend on phantom imaging of in-phase/equal level audio in the surrounds so that it resolves behind you, which tends to come across the same way headphones image - IN YOUR HEAD. 6.1 somewhat addresses this, but having a single point source that close behind you can trick your ears into making it seem like it's coming from in front of you. DPL-IIx Music Mode addresses this somewhat on a 6.1 system by leaving the in-phase surround in the side surrounds at a greater volume so that the three speakers act as a rear array (i.e. one speaker playing behind you plus phantom imaging at a lower level from the sides). 7.1 addresses this more directly in a home space - by placing two speakers behind you so that there's no psychoacoustic reversal, then ensuring that more than one surround is always playing audio steered to the rear (albeit in varying levels, which allows for precise placement).
So even though there may only be one theatrical 7.1 mix, that doesn't mean there's not a ton of material for 7.1 playback in the home, because the two spaces have different requirements for proper imaging.
(Don't even get me started on how DPL-IIz height helps recreate the ambient sounds typically mixed out of phase in the side surrounds as if they were coming from a large side to rear array with lots of space above you. That's a whole other discussion! )
http://translate.google.fr/#