Would there be any audible difference between dolby pro logic IIx and dolby EX if my rear surround speakers where right next to each other?

Because of my room layout I can't really have my rear surrounds far apart. Right now they are about a foot apart and directly behind me.

Should there be any real world difference between ex and PLIIx, given my situation?

does one of the formats send more info to the back?

Thanks,

Jason

Would there be any audible difference between dolby pro logic IIx and dolby EX if my rear surround speakers where right next to each other?Nope. In order to hear stereo separation between the two surround-back channels with PLIIx, your rear speakers need to be spread well apart (especially since our human hearing is not very good for sounds coming from behind us).

Sanjay

DPLII is a matrix system - multiple channels encoded into two - and Dolby EX is a discrete digital system. Everything else equal, DEX will sound subjectively better.

Your speaker placement compromises any rear sound playback. Our ears hear pretty well in Ls Rs stereo, but we can't hear a phantom image from directly behind us, so any two-speaker rear channel reproduction is compromised. A single rear speaker directly behind us is the answer for consistent rear phantom imaging - 6.1 should be the standard.

You may try angling these speakers out to increase the stereo spread for any format, but this will probably decrease the solidity of the rear image.

DPLII is a matrix system - multiple channels encoded into two - The OP asked about PLIIx. PLIIx can be applied to 5.1 material to create 4 new surround channels from the 2 that are encoded in the 5.1 soundtrack.

Everything else equal, DEX will sound subjectively better.Maybe with specifically encoded EX material


.............but we can't hear a phantom image from directly behind us, so any two-speaker rear channel reproduction is compromised. A single rear speaker directly behind us is the answer for consistent rear phantom imaging - 6.1 should be the standard.Boy, you're really asking for it. ;)

Do you mean in the OPs specific situation or generally?

DPLII is a matrix system - multiple channels encoded into two - and Dolby EX is a discrete digital system.

That's mostly right, except the rear channel(s) in DD-EX are still matrixed. PLIIx starts life as a two channel L/R feed, and all 7.1 channels are derived from it.
DD-EX starts as a 5.1 discrete signal, and the rear discrete channels are matrixed into the three(or four) rear channels.

As to the pros and cons of either, and to the pros and cons of 6.1 vs 7.1, I'm not touching that with a ten foot pole....
My asbestos undies are in the wash. :D

To the OP:

If you sit 2 feet in front of your rear speakers, that 1 foot separation may not be insignificant. If you are 12 feet in front of them, different story.


Sanjay,

I know it is sort of comparing apples to oranges but, generally, what is the difference between applying EX to EX-encoded material with a 6.1 setup and applying PLIIx to non-EX 5.1 material with a 6.1. setup. I guess what I am getting at is the subtle difference in there being an actual extra channel there that is extracted from the side surround channels upon playback versus matrixing 3 all-new channels from the 2 side surround channels. Maybe I just answered my question. :o

And is PLIIx applied to EX-encoded material as if it were simply 5.1 material? I guess what I am getting at here is whether there is anything "special" about the embedded extra channel in the EX soundtrack that causes it to be treated differently, either directly or indirectly, by the PLIIx matrixing algorigthm or is it simply treated just like any other mono material that happens to be in the side surround channels?

Would it be fair to say that with a 6.1 setup, applying EX to EX-encoded material is probably preferable to applying PLIIx, but with a 7.1 channel setup, PLIIx is probably preferable to applying EX to EX-encoded material?

Inquiring minds want to know. :)

TIA

Basic surrounds should be spaced and parted along the sides even in smaller rooms, providing of course of you what true surround from monopoles.

The centre back arrays are placed in tight configuration to give a solid centre back! So I can enjoy surround at the back of the room or mid way or right up front, now then.

5.1 is commonly misunderstood by a lot of people on this site its obvious they haven’t been to cinema in years.

The surrounds thou small in this room perform surprisingly well in all-modes monaural matrix, discrete monaural and stereo surround.

The spacing of the surrounds along the sides give the illusion of defused sound image within the (centre phantom mono) while at the same time I can pinpoint directional sounds just like in the cinema.

http://i279.photobucket.com/albums/kk123/IndianaJones34/JBLcontrol1extrawide1.jpg

http://i279.photobucket.com/albums/kk123/IndianaJones34/JBLcontrol1extrawide3.jpg

http://i279.photobucket.com/albums/kk123/IndianaJones34/JBLcontrol1extrawide2.jpg

PLIIx starts life as a two channel L/R feed, and all 7.1 channels are derived from it.PLIIx processing can also be applied to discrete 5.1 sources. The 3 front channels are left untouched. The 2 surround channels are matrixed into 3 or 4 output channels (depending on number of surround speakers configured). DD-EX starts as a 5.1 discrete signal, and the rear discrete channels are matrixed into the three(or four) rear channels.EX decoding matrixes the 2 surround channels to 3 (not 4) output channels. The surround-back channel is typically played back using 2 rear speakers, but that doesn't make it 2 channels. By comparison, PLIIx really does output 4 independent surround channels, with each channel getting unique content (no dual-mono rears like EX/ES).

Sanjay

If you sit 2 feet in front of your rear speakers, that 1 foot separation may not be insignificant. If you are 12 feet in front of them, different story.Right, the angle stays the same. So the further the rear speakers are from you, the wider their spread. Separating the rear speakers by roughly 60 degrees is a popular recommendation, for several reasons: far enough apart that it allows listeners to hear stereo separation behind them, close enough together that it maintains rearward directionality, keeping the rear speakers at least 30 degrees away from the centre line minimizes imaging reversals, spreading the speakers apart improves rear envelopment, etc. I know it is sort of comparing apples to oranges but, generally, what is the difference between applying EX to EX-encoded material with a 6.1 setup and applying PLIIx to non-EX 5.1 material with a 6.1. setup.No difference. In fact, when you configure a receiver for 6.1 speakers (2 sides, 1 rear), the PLIIx Movie mode disappears from the list of surround mode choices, since it is exactly the same as EX (no need for redundancy).

PLIIx Music mode is still there, since it operates differently from EX and PLIIx on 6.1-speaker set-ups. If you change the configuration to 7.1, you'll notice that the PLIIx Movie mode is back as an option, since it is different from EX (stereo rears vs dual-mono rears) on 7.1-speaker set-ups.

When using a single rear speaker, both PLIIx processing and EX decoding will extract correlated (in-phase) mono content from the surround channels and send it to the speaker behind you. Keep in mind that these mono sounds would have phantom imaged behind you anyway. I guess what I am getting at is the subtle difference in there being an actual extra channel there that is extracted from the side surround channels upon playback versus matrixing 3 all-new channels from the 2 side surround channels.Both modes result in all the surround channels being matrix derived. EX sums correlated mono info from the surround channels and sends it to the rear speakers. It also actively cancels that information from the side speakers (you don't want to hear those sounds from the wrong direction).

We already know that the surround-back channel is matrix derived. But it turns out that the surround left & right channels are also matrix derived, since the surround-back info has been cancelled from them, and they are no longer the same discrete channels that were originally on the disc. And is PLIIx applied to EX-encoded material as if it were simply 5.1 material?Yes. But there's no downside to that. On 7.1 set-ups, PLIIx can mimic EX. If a surround effect needs to image directly behind you, then PLIIx send the same signal to both rear speakers. However, the reverse is not true: EX can't do what PLIIx can. If a certain surround effect needs to image right or left of centre, EX can't suddenly run the 2 rear speakers in stereo. PLIIx can. I guess what I am getting at here is whether there is anything "special" about the embedded extra channel in the EX soundtrack that causes it to be treated differently, either directly or indirectly, by the PLIIx matrixing algorigthm or is it simply treated just like any other mono material that happens to be in the side surround channels?Since they are both Dolby products, PLIIx does recognize EX encoding. So, on a 6.1-speaker set-up, neither EX nor PLIIx have an advantage over the other. On 7.1 layouts, PLIIx has the obvious advantage. Which is why Dolby recommends using PLIIx processing instead of EX decoding, even EX encoded soundtracks.

Sanjay

PLIIx processing can also be applied to discrete 5.1 sources. The 3 front channels are left untouched. The 2 surround channels are matrixed into 3 or 4 output channels (depending on number of surround speakers configured).
Sanjay

Sanjay,

When using PLIIx on 5.1 sources, does the AQ in channels 4 & 5 degrade if the speakers used for channels 6 & 7 are inferior speakers?

To help explain my question, my side speakers are large, 65 pound, speakers originally used up front. I moved them to the sides (channels 4 & 5) when I bought new speakers for channels 1-3. I now use my old small ceiling speakers for channels 6 & 7 that were provided by my builder 12 years ago for surround speakers and they have average (at best) AQ. Therefore, I do not want the ceiling speakers to degrade the overall AQ by reducing the capability of the surround speakers. I am hoping that the audio in channels 4 & 5 are untouched, just used to derive the "new" 6 & 7 channel audio.

When using PLIIx on 5.1 sources, does the AQ in channels 4 & 5 degrade if the speakers used for channels 6 & 7 are inferior speakers?Each of your side speakers have to blend in with their adjacent front and rear speakers to form an arc of sound along your left & right hemispheres. The more closely you can match the sound of those speakers, the more consistent and seamless that arc. So if a jet plane flies overhead (its sound pans from front to side to rear speakers), it may be distracting if one of those speakers sounds noticeable different from the others. I am hoping that the audio in channels 4 & 5 are untouched, just used to derive the "new" 6 & 7 channel audio.Depends on the mode you use. PLIIx Movie mode derives rear information, then cancels that info from the sides, in order to emphasize rear-vs-side separation in the surround field. PLIIx Music mode derives rear information, but doesn't cancel that info from the sides, emphasizing rear-plus-side envelopment. The latter seems to be what you're looking for (don't worry about using a "music" mode for movies, the surround police won't come after you).

If you already have this set up, why don't you give 7.1 playback a try? It's not like you're going to hurt anything. Chapter 11 of the Disney movie 'Mission to Mars' is a good torture test, since it has a dialogue that circles the room. If you find the rears distracting, then stick to 5.1 (until you get better rear speakers). If you don't hear much audible difference (or feel you could live with the compromise), the continue using all 7.1 speakers.

Sanjay

Thanks Sanjay!

Yes, I already have this setup and will not be able to change it for the foreseeable future. At least I finally understand what is happening in the PIIx Movie Mode; very difficult to find an explanation of how this mode works. I agree with your comment that the Music Mode may be a better possibility with my setup; I will give it a try!

I think that I have only viewed a couple Blu-rays that had 7.1 since I upgraded to Onkyo 805. Cannot remember there being much difference from a standard 5.1 movie, but have not watched enough 7.1 movies to really say.

Thanks again!

Hey guys, thanks for all the replies.