Help Surround Sound - utter confusion!!

[admin_exported]

hi

I know I'm being a bit of a novice but....i have just had a 7 speaker Arecam muso system fitted to my yamaha dsp ax863se amp... The speakers all work fine, but on DVD and bluray playback, i just can not get the two rear surround speakers to work...i get great sound but should there be some output form the back 2 speakers???

On DVD playback, if I set 'EXTD SURRD' on the Amp to Dolby PLIIx movie - it works and I get a little Dolby PLIIx icon in the Amp's display....but I'm now really confused about the Dolby prologic thing...I thought this was a setting that was encoded on the disc - so the DVD either has it, or doesn't - how come I was able to just turn it on like that?? My latest Tropic Thunder BluRay in True HD only has 5 channels of sound (says ont he box and on the Amp's input display) and only comes out of the surround, front and centre speakers, not the rear surrounds...

When I press sur decode on DVD playback (on the remote which is supposed to switch between different encoders) it just says Dolby Digital - and the DVD case claims the DVD is is "Dolby Digital",no mention of "PLIIx"??

Can anyone explain for me please - I'm just so confused (plainly) -is this normal - i know most audio is recorded for 5 channel output but i hoped to get 7 channels!!??

 

[Big Chris]

Pretty much all DVDs are only 5.1, so without any additional processing, you won't get anything out of the rear speakers. (The Lord Of The Rings trilogy (Extended versions), carry a 6.1 DTS Discrete soundtrack, so do produce 6 seperate channels of sound. (The rear speakers share a channel)).

To get sound out of the rear speakers you need to set it to DD + PL2x. Or if it's a DTS soundtrack, DTS + NEO:6.

DD PL2x & DTS-NEO:6 'create' a rear effect for your extra 2 speakers. It's not an actual audio track on the disc, it's a process the amp does for those with the 1 or 2 extra surround channels. So it's a simple matter of using DD PL2x or DTS NEO:6, or listen to it as the maker intended.

Blu-Ray will make more of your system, as a few (but not all by any means) have a 7.1 audio channel on the disc itself, so no need for the amp to do its 'electrickery'. 'The Bank Job' is one, the new Jackie Chan/Jet Li one is another (Can't remember the name, but it has 'Kingdom' in it somewhere).

Some say you should keep the audio track as intended by the maker. Others say that you'll get a more enveloping sound using PL2x or NEO:6. Switch between them and see which you prefer. I tend to use PL2x or NEO:6 myself when watching films with plain ol' 5.1.