DIY Dolby 6.1

Discussion in 'Archived Threads 2001-2004' started by BarryT, Sep 8, 2001.

  1. BarryT

    BarryT Auditioning

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    Could someone please refresh me on how to recreate DD 6.1 using two receivers. I have a Yamaha R-V1100 (DD5.1) and an old Yamaha RVX673 (Pro Logic) receivers. My thoughts were to simply run an RCA's from my DVD to the Pro Logic receiver and use only the rear effects from it. I question if this will work however as DVD's usually require you to differentiate whether you want DD or Surround so am not sure if I will still get the rear effects by running a DD signal into a Surround receiver. Thanks.
     
  2. Zacha R

    Zacha R Stunt Coordinator

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  3. BarryT

    BarryT Auditioning

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    Thanks fo the quick reply. The referred article talks about setting the Surround receiver in Dolby 3 mode. My Yammy doesn't have such a thing. Is this the fancy name for "phantom" mode ?
     
  4. Keith Mickunas

    Keith Mickunas Cinematographer

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    You need 3 Channel Logic or something like that. Its used for doing surround sound without the rears. The idea is to take the sounds meant for the rears on your main receiver and route them to the front left, right and center on the DPL receiver and position those speakers in the back of the room. If you used normal Pro-Logic on that second receiver some info is going to be routed to the rear channels on it, and you'll lose that sound in this configuration.
     
  5. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    Dolby 3-channel logic is sort of the opposite of "phantom" mode. With phantom mode the center speaker is not used and the left and right speakers will produce a phantom center image as in the classic stereo sound. With 3-channel logic, the rear speakers are not used, but the center speaker is.
    I'm not familiar with your Yamaha but if it has a way to tell it that the rear speakers are not present, it may use 3-channel logic.
     
  6. Joseph Anlacan

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    i did a pseudo EX set-up using an prologic receiver which has no 3-channel logic and neither can the rears be set to none. i was worried i was losing some information meant for the rears. so, i tried connecting some extra speakers to the surround channels of the prologic receiver. i found out that the sound information sent to the surrounds (of the prologic receiver) in this set-up is negligible. so, i feel even the normal pro-logic mode was acceptable in a pseudo EX set-up.
     
  7. Wayne Bundrick

    Wayne Bundrick Cinematographer

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    I read somewhere, I think it was from either someone at Dolby or someone at THX, that the "rear" signal (the out-of-phase component of the EX matrix analogous to the Dolby ProLogic rear channel) could one day be used as a 7th channel, most likely an overhead "Voice of God" channel. This would explain why the "rear" content is negligible... for now at least.
     
  8. JerryW

    JerryW Supporting Actor

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    I don't suppose this can be done with a DD receiver that doesn't have pre-outs, can it? My Onkyo is deficient in that department. My old Sony DPL receiver would seem to work perfectly for rear effects.
    ------------------
    "But you have to remember that a worm, with very few exceptions, is not a human being." - Freddy
     
  9. Wes

    Wes Screenwriter

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    Jerry, It would be difficult, here are a couple choices:
    1. Buy a external DD/DTS decoder, then run that to your Sony. (If your DVD player has a DD decoder it would work)
    2.Take your DD receiver into the shop and see if they could install preouts on the surround channels. (I had this done to a DPL receiver and it worked great. Cost was around $50.)
    3.Go out and buy a new receiver with preouts or an EX/ES receiver.
    Wes
     
  10. Kevin C Brown

    Kevin C Brown Producer

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    A couple of more things:
    1) Remember, you are routing the 2 rears from your Dolby Digital receiver to effectively the front inputs of extra Dolby Pro Logic receiver to extract the center rear (which is the fron center output). You don't care about the rears info being lost from the DPL receiver.
    2) And, for genuine THX EX/DTS-ES decoding, you do *not* want to use "Dolby 3 mode" on the DPL receiver. You want straight Dolby Pro Logic deprocessing. That's what THX EX/DTS-ES is: more or less straight DPL decoding to extract the rear center from the orginal L + R rears.
    3) You *would* prefer "Dolby 3 mode" in the DPL receiver for *standard* Dolby Digital and DTS movies. (Although straight DPL mode does sometimes work.)
    4) And even if you don't have an equivalent of "Dolby 3 mode" on the DPL receiver, all you have to do, is to use Y-cable splitters on the line level outs for the rears coming from the Dolby Digital receiver. Send 1/2 of the original signal to your rears, and send the other 1/2 to the DPL receiver. That way, you maintain the original signal to the rear speakers, and *only* use the extracted center rear channel from the DPL receiver to *add* to the soundfield.
    But yeah, you kind of need the pre amp outs on the Dolby Digital receiver!
    Fun stuff...
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  11. derek

    derek Second Unit

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  12. Jeff Hipps

    Jeff Hipps Stunt Coordinator

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    You don't need preamp level outputs to make this Ersatz EX system work. Just trundle on down to your local car stereo emporium (or get out your Crutchfield catalog) and get a couple of high level to low level adapters. They'll work just fine for converting your speaker level output to preamp level.
    I'm also in complete agreement with one of the posters above. Don't use Dolby 3. Straight Pro Logic without the surround speaker signal is the right ticket for this.
    Jeff Hipps
    Sherwood America
     
  13. Kevin C Brown

    Kevin C Brown Producer

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    Jeff- You really work at Sherwood? Cool! Great to see people who work for the companies that actually make this stuff cruising these forums!
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  14. Roger Dressler

    Roger Dressler Stunt Coordinator

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    >>And, for genuine THX EX/DTS-ES decoding, you do *not* want to use "Dolby 3 mode" on the DPL receiver. You want straight Dolby Pro Logic deprocessing. That's what THX EX/DTS-ES is: more or less straight DPL decoding to extract the rear center from the orginal L + R rears.
     
  15. Kevin C Brown

    Kevin C Brown Producer

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    Roger: I see you are from Dolby Labs and all... [​IMG]
    But. A lot of 5.1 material only has mono information in the 2 rear channels (older stuff in particular). So, if you use DPL processing to extract the center rear channel, you effectively lose the signal in the 2 rears. Bam, the rear soundstage collapses.
    The whole point to genuine THX EX and DTS-ES material, is that they specifically mix in-phase and out-of-phase material in the 2 rears channels to specifically route information to the rear center or to the rear left or to the rear right (or both) channels.
    If you use a "3 channel stereo mode" on material like that, you will *smear" the the signal meant for only 1 of those channels across at least 2. You lose directionality.
    So I still uphold that for genuine THX EX/DTS-ES material, that using straight DPL mode is the best way to go.
    For *most* std DD/DTS material, 3 channels stereo is the best way.
    And for *some* std DD/DTS material, DPL is the way to go.
    Ultimately, it's up to each listener though to decide which sounds best to him/her.
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  16. Roger Dressler

    Roger Dressler Stunt Coordinator

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    Kevin, you are completely correct on all points.
    What I was talking about was not a generic 3 channel stereo mode of some kind, but Dolby 3 (or 3 Stereo), which is what others in the thread said should be avoided in favor of Pro Logic. For L/C/R processing, they are identical. So, as you rightly say, with non-EX content, the sides can dry up, and this will occur equally with PL or 3 Stereo.
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    Roger Dressler
    Dolby Laboratories
     
  17. Kevin C Brown

    Kevin C Brown Producer

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    Roger- Ahhh, I missed that. I didn't know that there was an "official" Dolby 3 stereo mode. Yeah, I was talking about a generic stereo mode that just mixes the L + R into the center.
    Neat to see someone from Dolby on this forum!!
    Any hints on what's next on Dolby's horizon?
    Dolby Surround, Dolby Pro Logic, Dolby Digital (AC-3), Dolby Digital THX Surround EX, Dolby Pro Logic II, ... ?
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  18. Roger Dressler

    Roger Dressler Stunt Coordinator

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    Kevin, we're taking it on the road! Check out the In-Car Entertainment story at www.dolby.com.
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    Roger Dressler
    Dolby Laboratories
     
  19. JerryW

    JerryW Supporting Actor

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    That's what I get for not checking this thread for the last few days. Thanks Jeff! I suppose this is what you're talking about: http://www.crutchfield.com/cgi-bin/S...101PL2&o=M&a=0
    I'll get one on order today and see how it works out.
    BTW, it says it's only rated at 30 watts RMS. Will this be a problem?
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    September 11, 2001
    "Those who died will always be remembered.
    Those who killed will never be forgotten.
    We who remain will not let it happen again."
     
  20. John H

    John H Second Unit

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    I just installed a Yamaha DPL processor to generate a EX/ES channel. It does not have 3 ch stereo only DPL. My DD/DTS pre/pro supports THX post processing.
    How will "Adaptive Decorrelation" of the DD/DTS surrounds affect the DPL processing in the unit used for the center rears?
    John
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    Bedroom Based Theater
     

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