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Discussion Starter · #1 ·
I've ready many, if not all, of the threads relating to Dolby Pro Logic II and Pro Logic IIx, but have yet to see any posts addressing this simple question:


Is there any advantage to using Pro Logic IIx (rather than Pro Logic II) with my 5.1 system? When listening to stereo movies, I haven't been able to discern any difference between the two modes. Just wondering whether I'm missing something subtle.
 

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ProLogic IIx is for 7.1. You don't see it being discussed for 5.1 as ProLogic II provides all you need to expand stereo sources to your five speakers and sub. To answer your question, no, no advantage.


In fact, I'm kind of surprised your receiver is giving you the option of IIx if you're running 5.1. Usually if you have a 5.1 setup on a 7.1 speaker (with rears turned off) IIx shouldn't show up as an option. Which receiver is it?
 

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If PLIIx is an option, that suggests the receiver is configured with rear speakers. If so, PLIIx would reroute some of the audio for the surround channels to the non-existent rear speakers, sound that would be lost. When setting up a 7.1 AVR for 5.1, it is necessary to configure it without the rear channels.
 

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Discussion Starter · #6 ·

Quote:
Originally Posted by BIslander /forum/post/20816765


If PLIIx is an option, that suggests the receiver is configured with rear speakers. If so, PLIIx would reroute some of the audio for the surround channels to the non-existent rear speakers, sound that would be lost. When setting up a 7.1 AVR for 5.1, it is necessary to configure it without the rear channels.

The STR-DG710 is a 6.1 receiver. My speakers are connected to the terminals labeled "center", "front left", "front right", "surround left", and "surround right". The only unused terminals are those labeled "surround back".


The PLIIx decoder is available with this configuration, and it's the mode I've been using most of the time (PLIIx movie, to be precise). Like I said in my original post, I can't discern any difference between this mode and PLII, while there is a discernible difference between PLIIx and DTS Neo:6.


I asked the question because I vaguely remember a Dolby Laboratories podcast where I thought one of the engineers said that while PLIIx was primarily for 7.1, it also included some other advances that are not in PLII. Probably remembering wrongly.


Anyway, not sure how to interpret your post vis a vis my configuration.
 

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Configuring a receiver involves more than connecting the speakers. There are setup screens where you tell the AVR how many speakers you have. If you configure it as 6.1, then it thinks there's a rear speaker attached and it will send audio to the rear channel. The reason I suspect that you have your system configured as 6.1, even though you only have five speakers, is that PLIIx should not be available as an option if the AVR is configured for 5.1.
 

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Discussion Starter · #8 ·
I follow your logic, but it doesn't seem to apply. In the receiver's "system" menu, the SB (surround back) option is set to "NO". Still the PLIIx decoder is available and functions.
 

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Something doesn't add up. There's a note on p50 of the manual that says PLIIx cannot be selected if there is no surround back speaker connected. So, if you can select PLIIx, you have the rear channel activated or the AVR is not functioning properly. A reset of the receiver may be in order.
 

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Discussion Starter · #10 ·
You're right, and I agree that something doesn't add up. The manual says PLIIx is not available when no surround back speaker is attached. But PLIIx is available. There is no reset button on the receiver, so I'm not sure what you're suggesting. Anyway, thanks for your thoughts, and I guess it's not important anyway. I'll just use the PLII movie decoder when watching mono or stereo movies.
 

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Discussion Starter · #12 ·
Just went through the reset procedure, and redid the auto calibration. No change in what we've been discussing. Very difficult to understand. I'm beginning to think it's a design glitch.
 

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That's really weird, because without a surround back channel (or two) active, there should be no need for ProLogic IIx. It's primary function is to make 5.1 into 7.1, but it also works like ProLogic II for stereo sources (just making them 7.1 instead of 5.1.)


In a 5.1 system, if ProLogic IIx is for some reason available, I wouldn't expect it to be much if different than ProLogic II. They're doing the same thing with the available speakers. Maybe some surround info is lost (if it's trying to send it to the rear speaker that isn't there), but that's about it (although that would be enough for me to do something about it.) The fronts and sub channels should be the same with both modes.
 

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Well, if it is a design glitch*(really, Sony with a design glitch*...nuh uh...really...)


You have two options...


The simple one...

Simply don't use IIx


The extreme one...

Replace the receiver


* Sony has always had models that acted weird. Not sure if they do it on purpose(which you'd hope), or do it cause they just don't pay attention.


Take Pure Direct mode(the mode where all processing is turned off, where you are at pure 2.0). In most Sony you actually have to put the receiver in Direct(which is without all processing other than trim)...then you can select Pure to remove the "rest of the unnecessary" stuff. With Onkyo/Integra Pure mode is either in the round with the rest of the sound modes...or its own button that you can press no matter what the mode was BEFORE or after you press the button. Yamaha has always been a button. (there are some Yamaha that once the Pure button is pressed it won't even recognize remote commands)


So for Sony to make you pick Direct first...then select Pure...is a "weird way" to do it. And with some Sony, if you do select Direct, then Pure, you have to unselect Pure to then go back to the other sound modes(whereas Yamaha and Onkyo simply turn Pure off and go on their merry way).


And, this "Pure mode", I don't think your Sony has it. It is usually reserved for receivers in the $800+ range.
 
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