Pro Logic concerns

I finally got some cash together and added a center channel to my system. In doing so I've been experimenting with DPL a bit more for television. The thing is, I've noticed that many times when Pro Logic (or Pro Logic II) is enabled all it does is shove all of the sound into the center channel. Not just in quiet, dialogue-heavy sections either, but often during more active portions of programs.

Needless to say this has the notable effect of making everything sound much, much worse. Occasionally I'll catch something that I assume is broadcast encoded for Pro Logic as it will come out with proper seperation and Dolby Digital/DTS multi-channel soundtracks as well as games that I know are encoded for DPL II come out fine.

Is it just me and this is an issue with the processing or possibly my cable company as I get consistently bad sound (i.e. left channel only, right channel is present, but so faint it barely even exists) on a few channels or is Pro Logic just a horrible, horrible thing that converts to mono rather than merely a system to artificially create a surround field from a 2-channel source. As a purist I usually prefer not to muck about with something and listen to it in the way it was originally designed, but given the large number of programs supposedly encoded for Pro Logic I figured I'd give it a chance.

Classic Pro Logic was notorious for collapsing everything to the center if there was no matrix decoding. Pro Logic II is smarter about it, but if you've only got one channel or if one is significantly louder than the other then I'd expect PLII to treat it as a mono signal - and a mono signal would end up in the center channel.

Odd, while it makes sense I would have assumed that in this day and age almost every TV broadcast would be in stereo at the very least. Yet almost everything ends up being collapsed to center. I can't ever really detect a time where it takes a standard two channel input and actually matrixes it out into 4 or 5 channels. Given the rare occasions where it actually works I've always just assumed that these were likely encoded for Pro Logic. The really odd thing has been that when watching newer shows (i.e. the type that specifically mention how they're shown with surround sound and other such things that aren't supported in my system due to my cable setup) they're also collapsed to mono. I'd say it's a pretty strong bet that they'd be in stereo at the very least.

Something I have thought of is that since it was coming through TiVo the compression process might have stripped things down enough that it affects the sound, but double-checking with OTA has proven that this isn't the case.

Check the settings for CENTER WIDTH in the SURROUND CONFIG menu - this will control how Pro Logic II distributes data between the center and the mains, and a low value can very closely approximate a complete collapse to the center channel. Try something around 5 and see what you think.

I have had pretty good results with CENTER WIDTH set at 4 or 5 - you can try both and see what sounds best to you.

Re: "I would have assumed that in this day and age almost every TV broadcast would be in stereo." While with most major stations the signal may utilize the stereo feature, my experience is that in all-too-many programs the same signal is broadcast in both the right and left channels. This explains the lack of sonic impact with PL II - and it is not the fault of the equipment.

Just read through this thread and I had a thought for Belgand. Have you tried connecting your television audio to your 1070 via a digital connection? If you are receiving digital cable, your cable box should have a digital audio output. When you see shows, especially movies and sporting events, that advertise either "Stereo Sound" or "Surround Sound", you have to have the box connected via a digital connection to receive the Dolby signal the station is sending.

Of course, this only applies if the station and your cable company are sending the signal properly. That's a whole 'nother topic.

A digital connection should not be needed for "Stereo Sound" or "Surround Sound". It would only be needed if it said something like "Dolby Digital" or "Dolby 5.1"

Personally, I have found PLIIx-C setting to be very good for most TV shows, even if there is no explicit matrix encoding. I never get a collapsed to center sound field except with old PL (which really should not even be offered as a option on the menu). I would be very interested to hear the resolution to the problem (since it doesn't make sense).

A digital connection should be used for any and all digital sources, not just Dolby Digital.

There's no sense converting the digital data from a CD or digital cable box to analogue, when the very first thing that the receiver will do is convert it right back to digital.

Instead, it's better to pour the digital data directly into the receiver, and avoid extra (and unnecessary) D-to-A and A-to-D steps that could degrade the sound.

Right, right. I just meant that the problem would not be cured by using a digital connection. It should only occur if the receiver was inadvertenly put in PL mode instead of PL-IIx