7.1 vs. 5.1 - Meaningful difference?

Gchuva,

I'm quite surprised you don't hear a difference between 5.1 and 7.1. When I expanded from 5.1 to 7.1 (using Logic 7), I heard a very noticeable improvement is surround envelopment.

Thinking out loud: I assume you are using Logic 7, all speakers play the test tones correctly when setting speaker levels, and distance settings are adjusted.

Are your side speakers directly to the sides of your listening area; i.e., +- 90 deg, and not behind your listening area? Having both sides and rears behind the listening position defeats the purpose of 7.1.

Are the rear speakers spread apart (+- 160 deg) behind the listening position?

Thanks
Bruce

Ran across this recently...it's worth a read:

http://www.videoasylum.com/ht/messages/21783.html

Fishboat,

Interesting read. I agree that adding rear channel information; i.e., expanding beyond 5.1, adds spaciousness. That is what I meant by better suround envelopment. And I agree that you do not need to correlate number of source channels with number of speakers used in playback. Logic 7 and/or DPLIIx can generate 7.1 "discrete" output channels from various sources.

I had not heard their explanation before about phase problems with dipole side speakers being the reason for needing 2 rear speakers (7.1) versus a single rear speaker (6.1). I do agree that 6.1 is not a good choice, as a single rear speaker can lead to front to back image reversal as well as not providing the spread of sound intended in the rear, problems that can occur even if you use bipole or monopole sides.

In some rooms, 7.1 is not practical, such as the listening position being flush against the back wall (no room behind the listener for the pair of rear speakers). Room size is not an issue. Based on my own experience, unless your room layout just cannot physically support 7.1, I can't imagine why you would not go with 7.1.

Thanks
Bruce

Considering all of the DVD's are 5.1 I am not sure what benefit doing 7.1 would be.

Mds

Logic 7 and/or DPLIIx will extract and process the information in the 2 surround channels of 5.1 sources, and generate 4 channels for playback: 2 sides and 2 rears. These algorithms do not add anything that is not already in the surround mix, but distribute the information across 4 rather than 2 discrete playback channels for a better spatial presentation.

2 side speakers alone don't provide good front to back depth. 2 rear speakers alone don't provide good side to side breadth. With both side and rear surround speakers (7.1), you get better envelopment.

The proof of course is in the listening. If possible, recommend you listen to a properly set up 7.1 system (not necessarily that easy to find), and toggle between 5.1 and 7.1.

Thanks
Bruce