Experienced Calibration Question

Discussion in 'Archived Threads 2001-2004' started by Kirk Mango, Jan 4, 2003.

  1. Kirk Mango

    Kirk Mango Stunt Coordinator

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    I have calibrated and tweeked my system using the internal test tones of my preamp several times over the past 2 years. I have checked this at reference with avia and video essentials and all speakers except sub are pretty much at reference.

    Equipment
    B&K Ref30 Preamp
    B&K Ref 7250 - Center, and surrounds
    B&K Ref 2220 - Mains
    Sony 9000ES DVD Player
    Mirage OM5's - R&L Fronts
    Mirage OMC2 - Center
    4 Mirage OMR2's - Surrounds
    Rel Storm III - Sub w/nutrik connection

    The set up:

    All speakers are callibrated to reference of 75dB using the internal test tones of my preamp. The sub is callibrated to an average of 72dB (needle bounces between 71 - 72.5Db) taking into account the Rat Schak adjustment of 2-3 dB for low frequencies. My Mains are set to large so as to utilize the nutrik connection to support them at their natural rolloff point. The sub is also connected to the preamp through the sub out to handle all LFE. All surrounds are set to small (hz of OMR2's is 80-20khz)


    The question:

    When I go into the Optimode area of some of the newer DVD's and play there test tones I find all speakers equal and the sub barly audible. It is below 50 dB because it will not even register on my meter. I have checked this with Video Essentials (cannot use avia for my set up because of the nutrik connection to my mains and my mains having to be set to large) and found that the dB level of my sub mathes my other speakers (-2db for meter correction level). Why is this the case? Does anyone know the actual Hz level of the test tones for VE and for the test tone used by B&K's Ref 30 Preamp? Any ideas on this?

    KM
     
  2. Kirk Mango

    Kirk Mango Stunt Coordinator

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    OK, so no one knows anything regarding the THX Optimode section on the new DVD's? Bass is extremely low, anyone know why?

    KM
     
  3. Michael R Price

    Michael R Price Screenwriter

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    Possibly the gains in the REL sub are different for the speaker level and line level inputs, so the LFE is not at an appropriate level compared to the bass that is normally present in the mains signals. This difference may not have shown itself depending on how the calibration signals were set up.

    I would try to set the mains as large, set your processor to redirect the LFE to your mains and then use the speaker level input only on the sub. This should help even out the levels, but it may place added stress on your amplifiers and speakers because they now have to carry the LFE signal as well. You could also try setting all your speakers to small and using the line-level input on the sub to handle LFE plus the bass from all channels, although you might not like having reduced bass coming from the mains if your processor has a fixed 80Hz crossover.
     
  4. Jimmy P

    Jimmy P Stunt Coordinator

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    I beleive the Optimode tests are setup like Avias and use the small speaker setting.Lucas/THX suggests setting all speakers to small with sub crossover at 80Hz.
     
  5. Richard Cook

    Richard Cook Stunt Coordinator

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    It's worth pointing out, peraps, that the Optimode settings on THX DVDs are set so that you can adjust the sound and vision for a particular movie, ie the one on the DVD, therefore by definition the will not be a good reference for your sub.

    Hope this helps
     

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