SPL and receiver

Discussion in 'Archived Threads 2001-2004' started by ChadLB, Nov 9, 2002.

  1. ChadLB

    ChadLB Screenwriter

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    I used the spl meter and thx optimizer from monster inc and followed these directions:
    Set the meter to 80db C-weighting and slow responce.
    Now turn your receivers main volume control (the big knob on front of the reciever) till you read 75db on the
    meter at your listen position with the left main speaker playing it's test tone. This may seem a little loud
    but it's only for calibrating!

    Question:is it right that at like -23 on my receiver i ended up with the following:

    FL - 0 was used as main test speaker to read 75db
    center - (-7)
    FR - 0
    SR - (-5)
    SL - (-6)

    Do other people have odd settings like this.
    FYI the FR and SR speaker are about a 1 ft. farther from the center point of sitting then the FL and
    SL speaker.
     
  2. Bob McElfresh

    Bob McElfresh Producer

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    This is quite normal.

    If all 5 of your speakers were identical, and they were all placed on the edge of a perfect circle and all angled to face the exact center - then you should not have to do any of these adjustments.

    The bits of volume you add/subtract compensate for:

    - different speaker distances
    - different angles of your speakers
    - different brands of speakers
    - and the effect of nearby reflecting surfaces

    If you moved your equipment to a different room, your adjustments would all be different as well.
     
  3. ChadLB

    ChadLB Screenwriter

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    Thanks for the post...I wasnt sure
     
  4. ChadLB

    ChadLB Screenwriter

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    I havent had time to even watch a full movie since i did the adjustments. Guess I will have to wait.
     
  5. Lee Carbray

    Lee Carbray Second Unit

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  6. Lee Carbray

    Lee Carbray Second Unit

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    Sorry, the above quote is off the THX web site under the Optimizer section.
     
  7. ChadLB

    ChadLB Screenwriter

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    So using the thx optimizer is too high and not correct for volume settings?

    Which disc is better? Avia, SOund and Vision, Video essentials.
     
  8. Lee Carbray

    Lee Carbray Second Unit

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    Somebody else may be able to explain why not to use the optimizer to calibrate speaker volume.

    All three of those cd's should get the job done. I use Avia, but I have heard Sound and Vision is good, and much cheaper. Avia has more video test patterns than Sound and Vision I believe. You may have a hard time finding Video Essentials as it is out of production. If you are just concerned with audio I would go with Sound and Vision to save a couple bucks.
     
  9. ChadLB

    ChadLB Screenwriter

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    So I got the S&V disc and here is what my settings ending up being compared to THX Optimizer:

    at like -23 on my receiver i ended up with the following:

    FL - -2 was used as main test speaker to read 75db
    center - (-5)
    FR - -2
    SR - (-5)
    SL - (-6)

    Which isn't much off from the THX Optimizer....Interesting
    if you ask me.

    Where do most people set there receiver volume when doing this?

    I just turned it up until my Left main read 75db on spl meter....any other thoughts.
     
  10. Bob McElfresh

    Bob McElfresh Producer

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    Most of us use 75 db when doing this.

    I have sometimes used 80 db just because that is in the center of my SPL meter and makes it simpler.

    The receiver test tones are a great way to do a quick test/adjusment. But some receivers like Yamaha do not include a test tone for the LFE output. This is a problem if you have a external sub.

    The setup disks are nicer because:

    - They maintain the test-tones for many seconds while you adjust.
    - They do have LFE output tones.
    - They have have tutorials on how to level adjust.

    Hope this helps.
     

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