I currently have a 5.1 speaker setup, but am in the market for a new receiver and was wondering if it was worth getting the additional L/R rear surround sound speakers.

I live in a loft and my couch is fairly central, so logistically having 7 speakers will be no problem.

I have four questions:

1. Not too many SD-DVD's output Dolby Digital EX or Dolby Digital Surround EX, so I presume if you only have a SD-DVD player it is pointless in having the L/R rear surround sound speakers?

2. Some receivers support Dolby Pro Logic IIx. If the DVD (SD or HD) is outputting Dolby Digital 5.1 is it worth using Dolby Pro Logic IIx to get the sound output to the L/R rear surround sound speakers?

3. Dolby True HD and Dolby Digital Plus are the new Dolby sound formats for HD-DVD players. Are most new HD-DVD's using these sound formats and utilizing all 6 or 7 channels?

4. Are there any sites that provide detailed audio specs for all new HD-DVD's?

Thanks in advance.

1. Not too many SD-DVD's output Dolby Digital EX or Dolby Digital Surround EX, so I presume if you only have a SD-DVD player it is pointless in having the L/R rear surround sound speakers?
Not true. Dolby PL IIx does a wonderful job.
2. Some receivers support Dolby Pro Logic IIx. If the DVD (SD or HD) is outputting Dolby Digital 5.1 is it worth using Dolby Pro Logic IIx to get the sound output to the L/R rear surround sound speakers?Not some, but probably all receivers today will include PL IIx. And as I said above, absolutely worth it - especially if you have the room to faciliate a 7.1 speaker setup.
3. Dolby True HD and Dolby Digital Plus are the new Dolby sound formats for HD-DVD players. Are most new HD-DVD's using these sound formats and utilizing all 6 or 7 channels?I believe that there is a problem here. There are either no true 7.1 or very very few 7.1 disks. But disks with 6.1 content have mono rear information in a 7.1 delivery format. Hence, you cannot apply PL IIx to get stereo rears since the mono rears are delivered as discrete channels.

Ed

Dolby PL IIx does a wonderful job.
Not some, but probably all receivers today will include PL IIx. And as I said above, absolutely worth it - especially if you have the room to faciliate a 7.1 speaker setup.
Ed
Good to know. At the moment, I have an older Onkyo receiver. The Dolby Digital or (even better) DTS sound very good. PL II sounds ok, but not as good as Dolby Digital or DTS.

I am presuming from your post that PL IIx is much better than PL II.

I have and enjoy my 6.1 set up...well worth it IMO.

PL II sounds ok, but not as good as Dolby Digital or DTS.You're comparing surround processing (PLII) to lossy audio compression (DD & DTS). Two completely different technologies. Sort of like saying Photoshop looks OK, but not as good as JPEG. One is image manipulation (like surround processing) and the other is data compression (akin to DD/DTS). I am presuming from your post that PL IIx is much better than PL II.PLIIx is an eXtension of PLII, not an improvement (they use the same surround processing algorithms). PLII can only be applied to 2-channel sources, expanding them to 5 channels. PLIIx can be applied to 2-channel and 5.1-channel sources, expending both to 7 channels. Not too many SD-DVD's output Dolby Digital EX or Dolby Digital Surround EX, so I presume if you only have a SD-DVD player it is pointless in having the L/R rear surround sound speakers?Not pointless at all. 7-channel pre-pros have been around for over 20 years, pre-dating 5.1 source material by a full 8 years. Obviously, 7.1-speaker set-ups have never been dependent on 6.1/7.1 material, just like HDTVs aren't dependent on HD content. So don't worry how many channels are in the source material; it can be scaled to the number of speakers in your set-up, like how folks scale 480i video to their 1080p displays. Dolby True HD and Dolby Digital Plus are the new Dolby sound formats for HD-DVD players. Are most new HD-DVD's using these sound formats and utilizing all 6 or 7 channels?No, they're utilizing however many channels were in the original soundtrack. 5.1 soundtracks are still 5.1 channels when encoded in TrueHD or DD+. Stereo soundtracks are still 2 channels; movies like 'Casablanca' are still 1-channel mono on HD DVD. Using newer compression codecs like TrueHD or DD+ doesn't mean the soundtrack suddenly grows extra channels. The exception being when the original soundtrack gets re-mixed for home video.

Best,
Sanjay

Good info. Just a couple more questions if you don't mind.
> So don't worry how many channels are in the source material; it can be
> scaled to the number of speakers in your set-up,
> like how folks scale 480i video to their 1080p displays.
But, would you want to scale? For example, if you have Dolby Digital, DTS, True HD, etc (all with a 5.1) would you want to scale to 6/7 speakers using Dolby Pro Logic IIx? I may gain the use of my 6th and 7th speaker, but I have a feeling I would lose sound quality?

But, would you want to scale? For example, if you have Dolby Digital, DTS, True HD, etc (all with a 5.1) would you want to scale to 6/7 speakers using Dolby Pro Logic IIx?I would. The L/R surround channels contain some content that is common to both channels. Those sounds end up phantom imaging between the surround speakers, usually appearing to come from behind you. Of course for the phantom rear imaging to work properly, you need to be sitting exactly between your surround speakers. Move off-axis and the imaging collapses to the nearest surround speaker.

PLIIx extracts those sounds and sends them to the speakers behind you. Now you can sit anywhere and those sounds will always appear to come from the intended direction (behind you). No magic involved, just a pair of speakers in the back of the room (makes it difficult for those sounds to come from the wrong direction). So the directionality hasn't changed, the imaging has just become more stable (for all listeners). I may gain the use of my 6th and 7th speaker, but I have a feeling I would lose sound quality?What sound qualities do you feel you'll be losing?

Sanjay

You absolutely need the back channel. Whether you go 6.1 or 7.1 is probably a matter of taste, as the two rear channels will play the same signal for most formats on the market today.

And when you hear a real EX title, or 6.1 LPCM BluRay title, it's quite good!

And when you hear a real EX title, or 6.1 LPCM BluRay title, it's quite good!
That's what I would expect and am really looking forward to.

> What sound qualities do you feel you'll be losing?
If I understand correctly, you've taken a 5.1 sound source (i.e Dolby Digital 5.1) and processed it with PLIIx to get "extra" sounds to the 6th and 7th speakers. Would the L/R front, centre and L/R surrounds with PLIIx be as "good" as the original sounds when just using Dolby Digital 5.1? Do I lose something with this extra processing?

If I understand correctly, you've taken a 5.1 sound source (i.e Dolby Digital 5.1) and processed it with PLIIx to get "extra" sounds to the 6th and 7th speakers.Correct. Would the L/R front, centre and L/R surrounds with PLIIx be as "good" as the original sounds when just using Dolby Digital 5.1?The front channels are not touched by PLIIx. 3 channels, 3 speakers; nothing to process. Each channel is simply routed to its respective speaker. Do I lose something with this extra processing?No. Think of how a bitmap works, mapping a line or curve to however many pixels you want to use.

Likewise, the surround field is not just two mono pools of sound (the left & right surround channels). It's a continuous soundstage, like a smooth arc between the 2 surround channels. You can map this arc to 2 speakers, 4 speakers, 400 speakers, whatever.

The more speakers you use, the less you rely on phantom imaging. The less you rely on phantom imaging, the more stable your sound field. With PLIIx, each of the 4 surround speakers gets a distinct signal; no dual-mono like EX/ES decoding.

Rather than lose anything, you gain imaging stability and wrap-around envelopment that is simply not possible when using only 2 surround speakers.

Sanjay

Thanks. I've found this to be quite informative.

I already have Totem speakers all round for 5.1 sound with the existing receiver. I think I'll be picking up a pair of Totem Mite's a month or two after I buy my new receiver for the rear surround L/R channels.

You absolutely need the back channel. Whether you go 6.1 or 7.1 is probably a matter of taste, as the two rear channels will play the same signal for most formats on the market today.

And when you hear a real EX title, or 6.1 LPCM BluRay title, it's quite good!

I disagree strongly with that. You don't *NEED* the back channel. Everything is backward compatible with 5.1. There is no loss of sound information by using a 5.1 system (or less).

While I certainly appreciate the advantages of a 7.1 system, and find them substantive, it is not fair to characterize the addition of rear-back capabilities as hugely fundamental to the degree that it rises to a "need."