Another Dolby EX question

Discussion in 'Archived Threads 2001-2004' started by Joseph Anlacan, Jul 14, 2001.

  1. Joseph Anlacan

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    I'm planning to use an old pro-logic receiver to simulate a rear center channel. I was wondering how to calibrate the 3 rear channels with this set up? Can I still make use of Video Essentials or AVIA? How do you make sure the volume of the pro-logic receiver is set right? Hope someone could give me some answers.
     
  2. Kevin C Brown

    Kevin C Brown Producer

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    Here's how I did it:
    1) Hook everything up, and then turn off all processing in the DPL receiver. In other words, just let straight stereo through (but it does probably have to be powered on!). Then adjust levels as you normally. But, you have to use a combination of the rear L + R outputs on your source receiver/pre-pro, *and* the Dolby Pro Logic receiver's *front* L + R. You also have to keep an eye on the DPL receiver's master volume.
    In other words, you still have the source controlling your system's fronts. The L + R rears are now controlled by a combination of the source level adjustments, the DPL receiver's level adjustments (*front* L + R), and the master volume on the DPL receiver.
    2) Then use the internal noise generator in the DPL receiver to balance the center vs the L + R (the rear center and rear L + R in reality). >> But do not change the value of the front L + R on the DPL receiver.
     
  3. Wes

    Wes Screenwriter

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  4. Joseph Anlacan

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    Kevin,
    When I tried calibrating using the method you suggested, I got different results than when I used THX Optimode on Toy Story 2. With the Optimode, my adjustments were 2-3 dB higher. Which do you suggest is more accurate?
    Also, my other receiver does not have prologic 3 mode and the surrounds could not be set to none. Would the standard prologic mode be fine to use?
     
  5. Kevin C Brown

    Kevin C Brown Producer

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    Joseph- A couple things. One is that my understanding of using Optimode, is that it's mostly relevant for that particular disc; not a generic calibration. Two, is that when I have calibrated with the internal "white noise" generators on my DD/DTS pre/pro + DPL processor for THX EX/DTS-ES, I have also gotten different results than by Avia or Video Essentials. I think for the most part, it's really up to you in terms of what sounds better.
    For Avia and Video Essentials, for me, the sub was way too loud, so I stuck with the internal sound generators on my equipment. Try it either way and see what you like best.
    Wes and Derek, if y'all are out there, any comments?
    As far as processing modes, here's what I have found:
    - For THX EX/DTS-ES specific DVDs, using Dolby Pro Logic for the rears is the best way to go.
    - For *some* std DD/DTS DVDs, DPL sounds good.
    - But what I have found is that using a 3-channel-stereo mode for the rears works best on most std DD/DTS discs.
    The problem with using DPL on a lot of non THX EX/DTS-ES discs, is that the rear L + R soundfields collapse too much into the rear center.
    Another way around this is, to *split* the rear line level signals coming out of your source DD/DTS processor. Send one half of each (like for normal DD/DTS processing) to your amps, then to the rear L + R speakers. Send the other half of each to the DPL processor for the back, and *only* use the resulting center channel. (You can get these RCA splitters at Radio Shack.)
    That way, your L + R rears are *always* representative of the original signal. All you're doing is adding the rear center.
    But this isn't the best approach for genuine THX EX/DTS-ES material. In that case, the source material is specifically mixed for DPL processing for all 3 rear speakers.
    You could try it different ways, and again, see what you think sounds best!
    Also depends on if you have a "3-channel stereo" like mode for the rears processing. (Or even a 5 channel mode, but you're only using the front 3 channels on the back processor anyway.)
    Whew! Hopefully most of that made sense!
    ------------------
     
  6. Joseph Anlacan

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    Thanks. What I did was similar in concept. I had my main amp (Onkyo) LS and RS pre-out sent to a Yamaha to decode the rear L, C, R channels. I didn't remove the existing surround speakers connected to the Onkyo (main). I ended up with 5 surround speakers a pair of original LS and RS, and prologic decoded rear L, C, R. I placed the speakers like this (sorry for the crudeness: P is prologic decoded:
    FL FC FR
    PLS PRS
    LS RS
    PC
    I chose this configuration because the original LS & RS contained all the signals so I placed them in between. This way when there's a:
    SIGNAL --------------- SPEAKERS THAT WILL SOUND
    discrete LS signal --- PLS & LS
    discrete RS signal --- PRS * RS
    rear center (EX) ----- LS, RS, & PC
    combines LS & RS ----- all five
    Any comments?
    By the way, all the speakers are timbre-matched except for the rear center which is of a different brand (but is a dipole). All the rest are direct radiators.
     
  7. Kevin C Brown

    Kevin C Brown Producer

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    5 surround speakers, cool!
    Hmmm, but how are you connecting the Onkyo to the Yamaha? In other words, somehow you have to feed the Onkyo L + R rear signals as inputs to the fronts of the Yamaha. If you are using pre outs on the Onkyo, are you sure that the speaker level signals on the Onkyo for the LS and RS are still outputting? And hopefully you're not using a tape monitor loop on the Onkyo, because that would only feed the L + R *fronts* to the Yamaha.
    ------------------
     
  8. Joseph Anlacan

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    Yes, I was actually surprised to discover that despite connecting the LS & RS pre-outs (not tape monitor loop), the Onkyo continued to have output in the LS & RS speaker outs. I know this may not be true of some receivers.
    Just to reconstruct my set-up:
    ---FL---FC---FR---
    PSL............PSR
    SL......ME......SR
    --------RC--------
    PSL, PSR, RC (Yamaha pro-logic)
    SL, SR (Original SL, SR from Onkyo)
    I haven't auditioned this except for a few scenes from T2: UE. I'll tell you how it sounds when I get to try several discs.
     
  9. Kevin C Brown

    Kevin C Brown Producer

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    I would not have suspected that!
    For straight DD + DTS, it's a good set up, because the PSL and PSR speakers will be subdued with DPL processing in the back anyway.
    With genuine THX EX/DTS-ES stuff though, you might lose a little channel separation between the LS, RS and the RC speakers. (But there aren't that many discs out there anyway.)
    You could always manually turn down the level of the rears from the Onkyo (but then that might affect the signals going to the Yamaha too).
    Might be worthwhile to look through the Yamaha manual and see what kind of other DSP modes might be appropriate. (I had a Yamaha receiver once, and even though I really liked the modes in general, no 3 or 5 channel stereo mode for this application.)
    Fun, isn't it?
    ------------------
     
  10. Joseph Anlacan

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    Yes, it's fun. It's in continuously trying to do something or tweaking one's home theater that's fun. Sometimes, you get things right, sometimes you make mistakes.
    Thanks for the comments. Are there anyone out there who also use the original LS & RS for their pseudo EX set up, instead of the pro-logic derived LS & RS?
     
  11. Joseph Anlacan

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    Just an update.
    I tried listening to different discs with the above mentioned set-up. I was not very pleased. I went back to my original pseudo ex set-up.
     

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