5.1 vs dolby pro logic

right , my telly has dolby pro logic (speaker connections on the back) and my dvd is 5.1 but i need a receiver.
so whats the ins and outs of them both?


cheers,


Rob.

 

5.1 is just a way to talk about an AV speaker setup meaning 5 main channels (2 front, 1 centre and 2 rear) and 1 sub. Dolby Digital 5.1 (to give it it's full name) is a system for encoding 5.1 separate channels of sound. Most DVDs of modern films have a 5.1 soundtrack on them. In order to make use of this you will usually need an AV receiver that can decode 5.1 and have 5 speakers hooked up to it. You connect the digital output of your DVD player to your AV receiver. Some more recent TVs have a digital input and can also decode 5.1 (and they have connections for at least 2 rear speakers, and sometimes also a centre and sub). However, the sound quality is cr@p compared to even the cheapest AV receiver + separate speakers setup.

Dolby Pro Logic is an older system used to encode a rear channel aswell as front left and right. Someone correct me on this but I believe that Pro Logic has the information for the rear channel encoded in the analog signal for L & R channels and a DPL decoder will work it out and put the right info to the rear channel. You can play DPL soundtracks through stereo equipment and they sound fine. Dolby Pro Logic II (DPLII) is a much more advanced version of DPL that does essentially the same thing but the nice thing about it is that it also works on regular stereo soundtracks so you can get a kind of surround sound from just stereo material. It works (extremely basicly) by taking out of phase signals and piping them to the rear speakers. It also creates a centre channel from the L & R channels.

Most AV receivers have DPLII processing and with a 5.1 speaker setup it can create surprisingly good soundfields from stereo TV broadcasts and other stereo material. Better implementations (in more expensive receivers and AV processors) allow you to change the "width" of the centre channel to suit your preferences. Budget implementations (like on my Marantz) simply let you choose between a "Music" and "Movie" mode (where Movie has a narrower centre channel meant for dialogue).

Your TV has just vanilla Pro Logic which isn't worth much. You need a receiver to handle proper 5.1 (and above) soundtracks...and obviously 5.1 speakers too.

Michael.

 

jees,
ok i think i got you.
so dolby pro logic is just three channels , two rear mono , two main stereo and one centre?
so whats the deal with vanilla Pro Logic? the tv is a philips matchline pro logic.

cheers,

Rob.

 

DPL is just three channels: Left & Right front and rear centre. That's it. Vanilla PRo Logic was quite cool when it was the only surround sound format in existence...about 20 years ago

Michael.

 

wot Michael said. Having had DPL from 1994, and liked it, my 'discovery' of DPL2 and 5.1 in 2001 was a revelation - they are both light years better, with the full 5.1 being a real experience. For that you do need a half decent AVamp, and a subwoofer.