How do I know if a laserdisc is encoded with Dolby Prologic? Or did laserdisc ever use this at all?

Basically either the disc will have the "Dolby Surround" logo or it will be described as "STEREO" only but if you turn pro-logic/surround mode on your A/V Amp, you might still get channels on your rear speakers.

Julien

There are many many many LDs with Dolby Surround. Maybe even most of them. Due to the way Pro Logic works there isn't any way (that I know of) to know for sure if something is encoded with matrixed surround without turning on Pro Logic and trying it. Most Hollywood movies will state that they are in surround but there are quite a few things that are in surround and they don't say so.

Dolby prologic II is supposed to work on regular stereo mix. Prologic IIx can make any stereo source 7ch and prologic IIz makes 9ch. You dont get much seperarion in the back. Fronts usually work close to discrete surround as its not really difficult to decode left center right signal out of stereo signal.
Most new av receiver will not let you select pro logic as prologic II has been around for long time now. Some receivers have it as retro mode. My yamaha has it but mcintosh doesnt.
it is difficult to tell if one recording is dolby surround mixed. But at the end even if stereo only is mixed well dp2 can do real good job

From my experience messing with all sorts of enhanced modes, Neo 6, Logic 7, etc, things sound best when played in the modes they were designed for. The fancy DSP crap does generate a more enveloped sound space, but it also creates phantom BS in the surrounds many times, and rather than messing around with surround modes during a movie I just set them to what they were designed for.

One thing I must correct - there is no such thing as Dolby Pro Logic encoding. Pro Logic is the DECODING system for titles that have been encoded in the Dolby MP Matrix, which Dolby identifies as either Dolby Stereo (for theatrical releases) or Dolby Surround (for home releases). The MP in Dolby MP Matrix stands for Motion Picture, and only the very first licensed Dolby Surround decoder, the SSI-360, from Surround Sound Inc, carried the Dolby MP Matrix logo - after that, Dolby switched to Dolby Surround for home releases.

Pro Logic II is a different story - it refers to both encoded titles and the decoding system too. Except for video games, I don't know of any discs or music titles that are encoded in PL II.

DTS:Neo-6 was designed to decode Dolby Surround encoded films and DTS never made an encoder for it - Neo-6 is much more accurate in decoding Dolby Surround than Pro Logic or PL II because it breaks the spectrum up into 12-20 bands and decodes each band separately, which allows simultaneously dominant sounds to be decoded and placed in their proper channel wi no leakage of unwanted sounds or pulling non-dominant sounds towards the dominant ones. Pro Logic can only decode one dominant sound at a time and PL II is the same since both are broadband logic steering designs.

The VERY BEST decoder for Dolby Surround encoded LaserDisc's is the Shure HTS-5300 Acra-Vector Logic Steering Decoder. Although no longer made the Shure HTS decoders are the best of the best - Dolby even helped Shure on the design of the Acra-Vector logic steering to make it match the steering characteristics of the professional Tate DES based Dolby Stereo decoders used in Dolby's theater processors. There are two other Shure HTS decoders, the HTS-5000, which was their first and has a wired remote, and the HTS-5200 which was their second and has a wireless remote. The 5300, their third and last decoder was their most advanced with improved Acra-Vector logic that could steer two directions at once and built in pink noise test tone. Plus, all the Shure decoders have an incredible display that shows channel activity - it doesn't show channel levels like most receivers, but instead shows you what the logic decoder is doing so you always see where sound is being steered to - it's wonderful to watch.

The Shure decoders were so good that they started being used in Hollywood to monitor the mix downs on films, and many film sound mixers publicly stated that the Shure was more accurate than Dolby's decoder. Shure even came out with their own encoding system called StereoSurround. - CBS licensed it for all their programming like David Letterman and a few LaserDisc'a were released in Shure StereoSurround - Liza Live at Radio City Music Hall is encoded in Shure StereoSurround - and StereoSurround is fully compatible with Dolby Pro Logic and PL II decoding. Shure also started selling a full system of speakers and amps - this was before THX came on the scene - and THX didn't like it so they introduced their own system and Dolby began giving their MP Matrix encoder for free to new sound studios and such. Shure was a little company who, prior to this, was mostly known for their turn table styluses, and they couldn't compete with Dolby and THX so they got out of the home theater business.

Now you can get a Shure decoder for like $60 on eBay - they were originally $600-1000 - I got both of mine for less than $40. One is the wired remote HTS-5000 and the other is the HTS-5300 - I also got the Shure Demo LaserDisc from a forum member here.

I have a site where I've posted scans of reviews and tech papers for surround sound formats and such and have a scan of a review of the Shure HTS-5200 decoder. If you click on the circled "I" info button at the top and then Disclord, which will be in blue, it will take you to all of my publications.
Anyway, here's the review.
http://www.issuu.com/Disclord/docs/shure_hts-5200_review_high-fidelity_magazine_febru?e=2992104/4165453

Regarding Pro Logic II in something besides a video game: I think Netflix on Wii is generating Pro Logic II encoded stuff. I usually watch old TV shows on Netflix, so I can't say for sure, but I'm pretty sure I heard rear separation a couple of times. The Wii only has analog stereo outputs so its DPLII or nothing. DD/DTS aren't possible. There's probably some software they have that makes DPLII out of DD automatically for Wii users.

My cable boxes are all SD analog. It seems like they would put out DPLII too but I don't have cable in the home theater because TV is f***ing terrible.

Roger Dressler, formerly of Dolby Labs, told me that Dolby Digital Plus could be down mixed to PL-II and that HD-DVD players were supposed to do it for their analog outputs, but didn't for some reason - and reading your post, I recall that Netflix is using PL-II for low bitrate streams, when full DD-Plus can't be used. I think I've seen PL-II listed on a few Hulu Plus shows too. I have a demo DVD from Dolby that has a 5.1 channel music recording and you can also hear it down mixed to PL-II - except for some "slowness" of sounds being localized in the proper channel, it sounded quite good.

Yeah, PLII is actually pretty good, from what I've heard in video games anyway. They used it on Wii a lot and also Gamecube.

I read your HTS-5200 review, and as the HTS-5300 is better, I agree it should be the best Dolby Surround decoder around, much better than any Pro-Logic decoder!
The bad thing is it's not possible to find in here in Europe...

Interesting... but, it will be better than the Shure HTS-5300? If not, stating the Shure HTS-5300 at a score of 100 for quality - in particular separation, how could be the score for a DTS:Neo-6 decoder?

Thank you very much!

Ok, sorry if this is a stupid question. A laserdisc with Dolby Surround outputs the surround mix through both the two channel analog outputs and the digital audio output? I only need one of the two (analog or digital) hooked up to my receiver to get the surround mix?

Yes, some older discs are analog only though so I use both for just such an occasion.

OK, thanks. I just have the analog outputs hooked up at the moment, so I was wondering if I was getting it. I guess I'm just missing out on DTS, but I only have one or two discs that have it.

1- For ac3 you need rf demodulator which outputs digital optical and/or coax.

2- for digital tracks(pcm) and dts, you use digital coax or optical outputs.

3- some older discs will only have analog audio or commentary, you use analog rca outputs.

So all 3 are seperate outputs and need all 3 if you want to utilize all possible ld soundtracks.

Most rf demodulators except one or two has both rf input and digital input. They can act as a switch.

You can use analog rca output for digital audio as the player will convert digital to analog(never analog to digital)

All 3 output types can give you surround sound if encoded on disc. Rf and digital coax can give discreet surround sound(ac3 and dts).

Thanks. No demodulator in my system yet. Basically, I started buying LDs in 1993, pre-AC3. I had a receiver from that era that processed Dolby Surround, and I had some cheapo surround speakers, so I took advantage of that. I've since acquired some LDs with AC-3, and a much better receiver, but I've never acquired a demodulator, although the player I have now has an output.

A demodulator will likely be my next laserdisc-related acquisition, along with some decent surround speakers.

Thanks for all the helpful advice.