Dolby Pro Logic IIx explained? - Page 2

To me Pro Logic iiX Music mode sounds better for converting 5.1 sources to 7.1. To me the surrounds sound louder with music mode, which I like. I'm watching football now and it really feels like I'm in the crowd.

Can someone explain what happened with my setup? I use a phantom center. (Anthem AVM50v). When I use the LPCM setting on my Oppo BDP83, and engage Prologic IIX, ALL center channel information disappears. I have to use bitstream to get it back. Also, if I remember correctly, only Dolby True HD has this problem; DTS Master Audio doesn't. Why is that?

If the problem is a bug in the AVM50v, which is where it must be if the center channel disappears in phantom mode but not when the C speaker is activated, then it cannot be different based on the source codec.

If you are using the PLIIx Movie mode, try the Music mode, then adjust the Center Width control to max width (phantom C). Does that restore the center info? If so, it is a bug in the AVM.

Thanks Roger. I'll try Music Mode. And you're right. I remember now that I had the same problem with Citizen Kane in DTS-MA mono.

I have been using Dolby Pro Logic IIx on my HK AVR 2600 for some time now, and it appears to my ears that the HK Logic 7 Movie format is more pleasing to my ears when I am watching TV programming. So what is the difference between the two?

Is your TV programming mainly 5.1 or 2.0?

The tv programming input is pcm 48khz 2 channel.

In that case, it is a well worn path. Have a look at this thread, which gives both operational insights and personal opinions. A search will turn up more such discussions.

Thanks Roger. That link was very helpful.

Sorry to bring up an old thread, but I want to make sure I understand something.

I just went from 5.1 to 7.1 and was wondering what is the difference between DD ex and pro logic IIx movie mode when watching a 5.1 source?

thanks

EX is a 6.1 format. PLIIx is 7.1. They also have differences in how they matrix the rear channel(s). An EX-encoded 5.1 track is specifically designed for EX decoders to do their stuff, but the decoder can extract the rear channel from any 5.1 source that has sufficient stereo audio in the surrounds. PLIIx is just a decoder that is intended to be used on any 5.1 source.

Ok, thanks for the quick reply. So, in other words, if I'm watching a Blu-Ray that has 5.1 I would be better off setting the receiver to Pro-logic IIx movie mode than using DD EX? The reason being that in Pro-logicIIx the surround rears have 2 different signals while DD EX the surround rears just have the same signal?

I'm so used to wanting the receiver to say "Dolby Digital" so that I know I'm getting 5.1 sound, so I assumed that DD EX would be better but from you answer I was wrong.... right??

thanks rdgrimes

Depends on your AVR. Most will sent a mono signal to both rears for 6.1 audio. Some do not.
PLIIx is your go-to decoder for 5.1 sources. I leave it on all the time here.

Cool, I'll give it a try. I never used pro logic II when I had just 5 speakers for anything but 2 channel sources so this will be new to me. thanks

Careful not to confuse the compression codec with surround processing. Dolby Digital and DTS are lossy compression codecs (like MP3), and don't necessarily have to be 5.1 channels (I have plenty of DVDs that have 2-channel Dolby Digital tracks). Blu-rays can also contain Dolby TrueHD and DTS-HD Master Audio tracks, both of which are lossless packing algorithms (like zipping a computer file). Again, these can be any number of channels.

By comparison, EX and PLIIx are surround decoding/processing. They're designed to scale the number of channels in the soundtrack to the number of speakers in your set-up (just like a video processor scales the number of pixels in a standard def DVD to the number of pixels in your hi-def display). PLIIx is format agnostic, so it can be applied to any of the lossy or lossless codecs. PLII can only be used for set-ups of 5 speakers or less. As such, it can only be applied to 2-channel sources. You can't apply PLII to 5.1 sources because...well, what would it do: convert 5.1 to 5.1? It's only when you go beyond 5.1 speakers that your receiver will allow you to use PLIIx (for 6 or 7 speakers).

Ok, now I'm back to my original thinking. So you are saying that if I am watching a source that is 5.1 (most blu-ray's, some cable content) I should NOT use PLIIx? My options in those instances are:

1. Dolby Digital 5.1 - I don't want to use this because I want to use my 2 surround rear speakers.

2. DD EX - I was inclined to use this at first because my 2 rear channel surrounds will be playing, but they will be playing the same thing if I understand correctly.

3. PLIIx - I am still confused if I should use this or not. I know it uses the 2 rear surround channels but are the rest of the channels discrete? It looks like in you reply above that is not the case.

Remember, I have a 7.1 speaker setup now.

do not confuse PLII with PLIIx.

PLIIx is intended for use on ANY audio, stereo or 5.1 and always generates 7.1 audio.

Where did I say that? I simply explained that PLII can only be applied to 2-channel sources, not 5.1 sources. This was in reply to you saying that you had only tried PLII with 2-channel sources on your 5.1 set-up. My point was that you didn't have a choice: with 5 speakers you can only use PLII (PLIIx will be grayed out by your receiver), and only apply it 2-channel sources.

If you have a 5.1 source AND more than 5 speakers (6 or 7), you can use PLIIx to scale the number of channels in the source to the number of speakers in your set-up. For the record, I would recommend leaving PLIIx on for all sources, 2-channel and 5.1-channel. When PLIIx is applied to a 5.1 source, only the front channels remain discrete. 3 channels, 3 speakers, nothing to process. Each channel is routed to its respective speaker.

The processing happens in the surround field, where the contents of the 2 surround channels are steered over your 4 surround speakers. Sounds that are mixed to both the left AND right surround channels, and would normally phantom image behind you, are extracted and sent to the speakers behind you. Sounds that mixed mostly in either the left OR right surround channel are kept at your left or right side. This is how you get rear-vs-side separation in the surround field. Since each surround channel is separated into two parts, side and rear, they are no longer discrete (i.e., no longer exactly what was on the disc).

Ahhhhhhh *lightbulb goes on*

Ok, I got it now. Sorry, I'm a bit slow sometimes. Thanks for the detailed response sdurani and rdgrimes, I appreciate it. I feel a little out of my element wandering out of the subwoofer forum but I'm glad I did.

BTW, I cannot stop listening to music in PLIIx music for 2 channel music. When I had 5 speakers I preferred dts neo 6, but with 7 speakers I am absolutely loving PLIIx. I adjusted the center width a bit, and it's heaven.

This has been very helpful to me trying to figure out whether to use PLIIX or Neo:6 for 5.1 sources. Just to add another question / complication though: if you've set up Audyssey room correction on your receiver / processor, how does it work when adding PLIIX to a DTS-HD MA or DD-TrueHD 5.1 source? Though the Audyssey set up takes all 7 speakers into account in it's room correction calculation, how if at all is it implemented when PLIIX is added to a DTS-HD MA + PLIIX 5.1 sources? Is the Audyssey equalization still applied?

There is no relation between what happens upstream (audio decoding, surround processing) and downstream (room EQ). The room EQ works the same regardless.

DPL IIx Music and center width control: this is only active for 2.0 sources? I have a Marantz AV7005. and that setting disappears for 5.1 sources. I have a buddy with a Denon AVR, and the same thing happens. No center width control for 5.1 sources.

The reason I ask, is that if I have a 4.0 or 4.1 source, no center channel, I'd like to mix some of that L & R into the center, but it doesn't seem possible.

Maybe my understanding has been wrong. For both DPL IIx Music and Movie, the center and L & R are untouched?

The "center" width control is only controlling what's happening in the 4 surrounds?

Seems like "center" is the wrong word then for DPL IIx ... ?? Should be "rear matrix depth" or something ...
Edited by Kevin C Brown - 10/12/12 at 11:12am

Chattin' with a bud offline.

Maybe this is the case? For 5.1 content, DPL IIx (Music or Movie) doesn't mess with the L/C/R content, but for Music, the "center width" like control between the sides and surrounds is "internally preset somewhere in the middle". So no setting we have access to.

The actual "center width" parameter for DPL IIx is only active for 2 ch sources, like for DPL II, but does the same thing between the C and L/R channels.

??

Correct.
Not possible.
Correct.
Correct.

Thanks Roger.