aliEnRIK:RCduck7:
I have been experimenting a lot on this.
Yes, you can use 2 additional surround speakers over a 5.1 setup and use them as matrix/ex but i's not the same as a discrete 7.1 channels recording.
As a matter a fact i found it worse, i heard a few 5.1 movies on a 7.1 speaker setup with EX matrix on the receiver and the typical surround effects of these movies were gone, they don't reach the listener anymore, no placement.
For example, there is a soundtrack i know well with the "Daredevil" movie. At the end of the movie, ben afleck has to fight the big black guy. When ben is on the floor and had a daydream the black guy talks to him. And as ben comes out of his daydream you can hear the black guy's voice coming from behind to the front before he attacks. in ex/matrix mode this effect is gone. Allthough i tried different positions of the back surrounds and even set them louder then they're supposed to sound, it doesn't help much.
The same thing in the Gladiator movie, when they take gladiator to the woods to murder him he had a chance to escape. He threw an axe to a soldier running away on a horse. As the axe find it's way to the soldier you can hear it going from back to front. In 5.1 with direct radiating speakers you have to be in or close to the sweetspot or the effect will be gone. But with 7 speakers the effect misses it's purity and placement. It makes me wonder how it would be with bipoles.
Thats very similar to what ive found when playing about with my dads system.
We also found that by switching off the 2 rears the overall sound quality became better (Probably due to the hugh amps he uses ~ too much power being drawn)
Interestingly, when he used a pioneer integrated and he then bought a separate 2 channel amp for left and right duties the REST of the system sounded better too (Like the pioneers power supply wasnt big enough to drive all the speakers, so when left and right were take away it had a lot more room to breathe)
Low power couldn't be the case with me, i tried this with the AV receiver but also with a seperate multichannel amp, and the speakers aren't that hard to drive. I blame it on the EX processing in the AV receiver, if it is not the receiver which i doubt it is becausse i could try a friend his rotel processor to for a few days. It should be the EX processing standard in general that makes a compromise to integrate the other back channels. I agree, the moment you go from 5.1 to 7.1 there is a sense of more ambience and being present in the movie. This made me made up my mind that 7 channels is the way to go, and i listened for years to 7 channels. But the moment sound effects come in play, it seems EX makes bleeding them through the other back channels which removes the discrete effect. It took me a few years to realise that though as it has to be a certain sound effect going on from behind, the moment i was listening to certain effects in movies (as mentioned above) in 7.1 and switched to 5.1 the difference became all clear. Shame i have been looking for movies with 7 channels while 5 made the sound effect sound as intended for me. Is it down to the room? I think not, it is now my 3rd room my setup is in and the room i have now is 4m15 by 6 meter. looks pretty ideal for me.