Potential 8.1 Setup

Discussion in 'AV Receivers' started by Mike*Sch, Jul 2, 2004.

  1. Mike*Sch

    Mike*Sch Stunt Coordinator

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    Hi,

    I have a home theater setup which currently has 6.1 channels using a Pioneer VSX-D811S receiver. I read an article in a magazine a while back which talked about using 2 Smart CS-3X, Jr.s to decode left center and right center front channels, essentially replicating the SDDS 8-Channel configuration. I'm considering doing this, but before I purchase 2 CS-3X, Jr.s, I want to make sure that I'm not overlooking anything major.

    In addition to the 811, I also have a VSX-D411 receiver. My plan is to use the 811, which has pre-amp outputs for each channel, as my receiver, and the 411, which has 5.1 channel inputs, as an amp for my front speakers. From the 811, I would output the left and center channels to one Cs-3X, and the right and center channels to the other. Then from the 2 CS-3Xs, I would output the 5 screen channels to the 411. The 5 front speakers would be connected to the 411, and the 3 rear speakers and sub would be connected to the 811.

    Is there any reason to think that this wouldn't work? Also, am I correct in assuming that since the 411 is essentially just acting as an amp, the volume for all 9 speakers can be controlled by the 811?

    Thanks,
    Mike
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    I dunno, but is it even beneficial? The reason for SDDS was for the very very large theater screens in the hugest of auditoriums (something like Cinerama).

    I can't see too many benefits for a small HT screen, and it may be harder to get the imaging as good, but I dunno. It seems like a lot of effort for not too much (if any) benefit. IT may even be worse, dunno..
     
  3. John Garcia

    John Garcia Executive Producer

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    If you don't have an absolutely huge room, I can't see a benefit either.

    By using the 411 as an "amp" for your front speakers, you would be stepping DOWN in power...not the right direction IMO. IMO, you should use the weaker amp for the REAR channels.
     
  4. Mike*Sch

    Mike*Sch Stunt Coordinator

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    Thanks for the advice. The room I'm using is not tremendously large. The distance from left to right speaker is about 12 feet. Is it necessary that I do this? No. But I don't think it would hurt. Currently, I can definitely hear gaps when a sound pans from one speaker to another, especially if I'm not sitting in the center of the room (which is whenever I'm watching a movie with someone else). It's not distractingly terrible, but if I could improve the situation, then why not?

    In terms of imaging, I would not be moving any of the speakers from where I have them right now. I would simply be placing the new speakers in between the current ones. Therefore, I don't see how imaging would be affected. But I'm by no means an expert in theater sound, so if I'm wrong, tell me how.

    I should also state that I wouldn't use this for all movies. Primarily, I would use it for films which were in 8-channel SDDS theatrically.

    As for the power issue, this is something which I considered, but as far as I can tell, both receivers have 100 watts per channel. Is this incorrect? If so, I wouldn't do this. The reason for using the 411 for the front and the 811 for the rear is that the 811 has EX/ES and outputs for each channel. So I don't think that it would be possible to do this the other way around.

    When it comes to the work involved, I'm OK with that. Figuring out how to do this and then setting it up is half the fun. The only two things which would stop me is if it would make my system sound worse, or if it was too expensive.

    Am I still completely off-track? My big question is, will this set-up physically work? I've never used pre-amp outputs before. Is that even what they're called? Can you plug those directly into a receiver's 5.1 Channel input and have them work?

    Thanks Again,
    Mike
     
  5. John Garcia

    John Garcia Executive Producer

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    Yes, if you hook it up this way, it should work fine. I don't think it will make your system worse, but I don't think it is going to be the next big thing either. Yamaha already offered something similar to this with the "front effect" channels, essentially giving you 5 front channels, which I don't think they offer on any receivers currently (I wasn't impressed with this feature). I'm currently working on a friend's system, and he has an older Yammie with this feature, but we didn't hook it up this way.

    If it's just the entertainment value you are looking for, then by all means DO IT! [​IMG] It's worth a shot, but if it is going to cost a lot, like you said, I'd put that money towards something more useful, like a better sub.
     
  6. Mike*Sch

    Mike*Sch Stunt Coordinator

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    I know that there are no SDDS discs, but my assumption is that most of these films are mixed for 7.1 and then simply downmixed to 5.1 for SRD & DTS, and that the mix used for the DVD is usually the same as those. The only real question is how those extra channels are apportioned to the other channels for the 5.1 mix. As I understand it, SDDS decoders favor the left and right channels 75% to 25% over the center channel. But from what I've been told, many filmmakers (including Steven Soderbergh) disperse the sound at an even 50/50 between the two adjacent channels. When this is the case, it would seem that the placement of sounds in my potential setup would be fairly similar to that of the film's 7.1 mix. If the standard SDDS ratio is used, then it would seem to be more conservative, placing less information on the extra channels than the 7.1 mix. My reasoning for not using this setup for films mixed in 5.1 is the same as most people's reasoning for not using EX on non-EX films.

    The only thing I'd have to buy are the two CS-3X units. If this setup doesn't work out, I could still use them for other things. So I have to decide if I want to spend the extra money or not.

    Otherwise, it's good to hear that, technically speaking, this setup would work. But still, if anyone thinks this is a bad idea, please let me know.

    Thanks,
    Mike
     
  7. Chris

    Chris Lead Actor

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    I don't know.. I'm all confused on the 7.1 setups; I "get" mentally how 6.1 is beneficial (a center channel rear) but 7.1 hasn't yet clicked to me as to what it effectively really adds, in that it seemingly eliminates the center rear which I see use for, and adds "rear sides" which I'm unsure of.. I'll have to test it all out, I suppose [​IMG]
     
  8. John Garcia

    John Garcia Executive Producer

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    There is basically no difference between 6.1 and 7.1, just two rear speakers rather than one. With the exception of a few specific DSPs, the rear information is the same, but the extra speakers spread the sound out further.
     
  9. Jim J

    Jim J Second Unit

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    I think there might be some issue with levels when splitting the center too...
     
  10. John Garcia

    John Garcia Executive Producer

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    With a 7.1 receiver, there should be no problem with levels, since there should be individual adjustment. With a 6.1 receiver, if wiring series or parallel, there will be a difference in levels, but both speakers would be controlled by that's channel's level adjustment.
     
  11. John Robert

    John Robert Stunt Coordinator

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    Let us know after you try it...

    John
     
  12. Jim J

    Jim J Second Unit

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    What I mean here, is that the pro-logic steering routines are highly dependent on the levels of the respective channels.

    So if we've got a signal that is equal levels in the center and the right channel, it will image in the space between those speakers. I think the issue at hand to extract the signal and place an actual speaker there.

    He's got to send the center to 2 different processors, so it needs a splitter. splitting that signal reduces the level by 6dB (or is it 3dBs? anyway). Adjustments are going to be needed to account for this.

    It is going to be tricky no matter how you slice it.
     

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