dolby prologic

[stunna]

the other day i was setting up someones home theater
their dvd player was connected to the reciver with just left and right RCA cables
and i was able to get 5.1 sound
the reciver also had the dobly prologic lights on
can someone explain how surround sound works if i just had left and right connected?
thanks

 

[strid3r]

It takes information from the right/left channels and creates a center and rear channel. I have a older receiver that does Pro Logic, but personally I wouldn't use it unless I was desperate for surround.

 

[stunna]

so its like fake surround sound?

 

[strid3r]

so its like fake surround sound?

Yep. It's not true discrete 5.1.

 

[tenken]

It's not discrete digital surround sound, but it certainly isn't fake. Before Dolby Digital came about, Pro Logic (among other means) was what was used in cinemas. More info can be found at the wikipedia entry, http://en.wikipedia.org/wiki/Dolby_Pro_Logic --

 

[jpmkm]

Dolby prologic is indeed true surround sound, but it isn't 5.1 channel surround sound. A single rear channel and the center channel are matrixed into the standard stereo channels. The prologic reciever has filters that are able to extract that information and send it to the proper channels. Unfortunately that wikipedia page doesn't have a whole lot of information about dolby prologic. Search around a bit, though, and you'll be able to find a better explanation than I can provide. In any case, prologic should be a last resort when playing dvds. Just use the digital out and be done with it.

 

[strid3r]

It's not discrete digital surround sound, but it certainly isn't fake. Before Dolby Digital came about, Pro Logic (among other means) was what was used in cinemas. More info can be found at the wikipedia entry, http://en.wikipedia.org/wiki/Dolby_Pro_Logic --

You're right, it's not "fake" surround, I should've explained more clearly. I was thinking from a discrete 5.1 view, not surround sound in general.

 

[stunna]

i guess this explains how my cousins xbox and his theater system was giving pretty good music from the games

 

[azrael201]

actually xbox games like halo and sega gt have 5.1 so you won't have to use pro logic or that's why it sounds much better than the other non dolby digital games.

 

[SilverMK3]

actually xbox games like halo and sega gt have 5.1 so you won't have to use pro logic or that's why it sounds much better than the other non dolby digital games.

Its not the games themselves, its the XBOX (assuming you're connecting it to your receiver via optical SPDIF). NVIDIA co-developed the Dolby Interactive Content Encoder (now called Dolby Digital Live) with Dolby Labs when the X-Box was designed, this was the exact same technology used for the SoundStorm APU on some NFORCE2 motherboards.

 

[stunna]

oh i see
but i think my cousin has the xbox connected through rca cables not spidf

 

[mustang_steve]

so its like fake surround sound?

Ther right terminology is Matrixed surround sound.

What pro-logic does is takes the left and right channels and fuses them at a spcific frequency range for teh center channel, then takes both channels again, at spcific frequencies and does a minor phase shift for the rear channel (rear is mono in pro-logic)

Now...there is a ProLogic II out that Matrixes a 5.1 output....It's a lot nicer, and pretty convincing overall, especially with music. However it's still matrixed. The ProLogic II method of matrixing is far more complicated than the original pro-logic as well, this may have something to do with how much nicer it sounds.