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THX OptiMode/Receiver Test Signal Conflict

Discussion in 'Archived Threads 2001-2004' started by James Edward, Jul 27, 2001.

  1. James Edward

    James Edward Supporting Actor

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    Here goes: I know I need AVIA, but for now, I am trying to use THX OptiMode to balance my speakers. The one from T2 varies wildly from the one on Castaway, and THEY both vary from my receiver. I am NOT trying to set 'reference level', just the level between speakers. For example, I used T2 OptiMode, set the levels equally, then tried the OptiMode from Castaway, and the readings were VERY different. Surrounds down in level 5 db from the fronts, etc.
    Should the discs vary like that? Is there one THX OptiMode movie disc that is known to be correct?
    Or should I just use the receiver tones for now, until AVIA arrives.
    And why do we put ourselves through this?
     
  2. Jay Mitchosky

    Jay Mitchosky Producer

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    It's not uncommon for source-based test signals to vary compared to those from the receiver. This is why it's generally recommended to do final system calibrations using VE or Avia - you get a truer representation of what the signal has to do before it hits your speakers.
    In the case of variation between different copies of THX Optimode I think the issue at hand is that those were the respective calibrated levels for each transfer. So T2 Optimode would be appropriate for T2's audio master, likewise for Castaway Optimode and Castaway. The same applies for the Optimode video signals. When calibrating using movie-specific Optimode signals you are said to get a more accurate presentation. But this flies in the face of a "reference standard" like Video Essentials where everything is supposed to be based on the same expectation. In reality, however, this is not always the case.
    You may choose to do a single calibration of your system (as I have) using a master reference such as VE or Avia and leave it as such. This will probably be more appropriate for more titles than would be using Optimode from a select disc. Alternatively you may do a master calibration and adjust for each movie, but just not save the settings so your system reverts to MASTER when done - some receivers and pre/pros make this easier by allowing on-the-fly level adjustments that don't save to memory. Others you will need to note and return to the original settings.
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    --Jay
    "No one can hear when you're screaming in digital."
    My Home Theatre Pictures...
    "You're no mesiah. You're, you're a movie of the week. You're a ... t-shirt, at best."
     
  3. Pete Mazz

    Pete Mazz Supporting Actor

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    It's my understanding that the older Optimode signals were incorrect. I believe the Castaway tones are the corrected ones. Avia is still a very good idea, tho.
    Pete
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  4. Mario_C

    Mario_C Stunt Coordinator

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    That is correct. The older Optimode test tones were recorded at 85dB not 75 dB like the menu says. Also, the Dialog Norm was left on reducing the output to 81dB. You can still use T2 optimode to balance your speakers and to set them to reference levels just calibrate to 81 dB. I have confirmed this using my receivers test tones and the Ultimate DVD Platinum test tones (wich are recorded at 85dB).
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    My Music & Home Theater System
     

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