audio calibration question...

Discussion in 'Home Theater Projects' started by Shoaib Lateef, Dec 31, 2003.

  1. Shoaib Lateef

    Shoaib Lateef Second Unit

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    using my receiver's internal test tone (called either white or pink noise), how do i calibrate using an spl meter?

    do i place the meter at the primary listening position (like on the sofa where i sit) and then just adjust each speaker to 75db? and when playing the test tones, does it matter where the volume on the receiver is set to? (i'm not at home, so i can't check it currently)

    any recommendations, please?
     
  2. Brian L

    Brian L Cinematographer

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    Your understanding is correct.

    Place the meter where your ears normally are, and run the tones. As for volume knob settings, if your receiver is calibrated in dB, you would normally set it to 0 dB, then run the tones for 75 dB.

    If its not calibrated in dB, set it to whatever is needed to get 75 dB, and remember that setting. Then when you play a movie, you can set the volume knob to that setting, and know that you are playing back at calibrated reference.

    Of course, for most people in normal rooms, reference level is way too loud, so listen at whatever level is comfortable. The key is to have all channels calibrated to produce the same level.

    BGL
     
  3. dougW

    dougW Stunt Coordinator

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    To that I would add:
    Putting on a tri-pod in your sweet spot with the meter mic facing straight up insures equal measurements to each speaker with meter mic at or slightly above ear level. Also, be sure to not stand between the speaker and the meter.

    The Radio Shack analog meter should have weighting set to "C". The 75 dB level is the correct level to set to.

    See if your white noise is volume sensitive. Easy to do, play it and adjust master volume. If it is volume sensitive, set to zero db setting, then adjust meter to 70, use plus volume for each channel to get to 75 precisely while on the zero dB setting on master volume. Use good judgement, gradually increase to that point, and if it gets to loud for your speakers, don't go that loud with the master volume or the individual increments.

    If the noise is not master volume sensitive, again weighting to "C", meter to 70, and adjust individual channel volumes to 75. (70 + 5 dB on the meter).

    Only difference is, the zero dB setting on the volume if the noise is master volume sensitive.

    I would also add to the above, before you start, check your speaker positions. Align as equal as possible to the listening spot. Also, front mains should be toed in slightly, and as much in front of any RPTV box as possible to allow them to image the best possible.

    Lex
     
  4. Shoaib Lateef

    Shoaib Lateef Second Unit

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    thanks guys!
     
  5. Vince Maskeeper

    Vince Maskeeper Producer

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    Shoaib,

    There is a step by step set of instructions on calibration with a meter in the FAQ and PRIMER, link in my sig.

    -V
     

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