basic Speaker Calibration question...

Discussion in 'Speakers & Subwoofers' started by Jason8, Dec 7, 2003.

  1. Jason8

    Jason8 Agent

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    I have the Radio Shack sound level meter and the Avia disc, but am confused what volume level should I put my receiver at when I do the test tones? In turn, what db level should I put my sound meter at? Lastly, according to the readout, what calculations do I need to do to figure what +/- DB I should put my speaker levels at?

    Thanks!!
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    Ideally you'd want to calibrate to reference with your volume at 0, but you don't need to. Primarily, the goal is to get all your speakers at the same volume level. To do this, set your receiver to a reasonably loud level, and then play the test tones. Your meter reads in dB, you turn the dial to set the range of loudness that it reads. Get it so the needle is reasonably in the middle of some range that you're playing, and read the volume. Then switch to the other channels, and adjust as necessary so they are equal, no calculations necessary. If your L speaker reads 75 dB, and your center reads 77, then turn down the center by 2 dB, and check. Hope that simple explanation helps.
     
  3. Hank_P

    Hank_P Second Unit

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  4. Jeff smit

    Jeff smit Agent

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    Do you leave the spl meter aimed at the front sound stage or do you aim at the speaker being set?

    thanks
     
  5. David Judah

    David Judah Screenwriter

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    There are different opinions on that, but most of the calibration discs including Avia recommend pointing it upwards and at a slight angle towards the front. Make sure you also have it on "slow" and "C-wieghting." It's best if you can prop it up with a tripod or something similiar so your body doesn't interfere. If that's not an option, hold it out away from you.

    Avia actually has an SPL meter primer.

    DJ
     
  6. Jeff Gatie

    Jeff Gatie Lead Actor

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  7. Edward J M

    Edward J M Cinematographer

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    Actually, the suggested volume to play the test tones refers to the DVD mastering level with respect to Dolby Reference Level. The VE and DVE tones were recorded at 30 dB below RL, and the Avia tones were recorded at 20 dB below RL (with RL being defined as 105 dB for the surround channels).

    Assuming Avia and VE are both accurate, using 75 dB for VE and 85 dB for Avia "should" yield an almost identical overall sound pressure level at any given Master Volume level.

    Regardless, you can use any reasonable sound pressure level (70, 80, etc.) to balance all your surround channels. But you must use a set Master Volume level (usually 00) and 85 dB for the test tones IF you want to also calibrate the system to Dolby Reference Level.

    Calibrating to RL allows all enthusiasts to have the same benchmark when comparing master volume settings and associated sound pressure levels.

    I wish I could say that setting the Master Volume to 00 after RL calibration with Avia yielded sound pressure peaks of 105 dB in the surround channels and 115 dB in the LFE channel every time for every Dolby Digital DVD, but it just isn't true. Some DVDs are mastered very hot, and other ones are not.

    So ultimately it's best to view RL calibration as a standardized benchmark for enthusiasts than an absolute playback level because we can't control the mastering level in DVD movies.
     

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