RS meter correction values

Discussion in 'Archived Threads 2001-2004' started by John H, Feb 22, 2002.

  1. John H

    John H Second Unit

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    Do the frequency correction values apply to both the analog and digital models?
    John
     
  2. ColinM

    ColinM Cinematographer

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    Yes...

    The only diff is the display.
     
  3. Mark Guidry

    Mark Guidry Stunt Coordinator

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    What are the frequency correction?? Is there a problem with the RS meters?
     
  4. Alex Prosak

    Alex Prosak Supporting Actor

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    I second Mark's question. I got a RS sound meter from my father-in-law but he didn't have the manual for it. It seems pretty straight forward but I keep hearing about some corrections. What are they? Thanks.
     
  5. brucek

    brucek Second Unit

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    Guys,

    The RS SPL meter is far from perfect, but can generally be compensated for using the following values. This is the corrected values for 1/6 octave from 10Hz to 160Hz and 1/3 octave after that.

    10Hz +20.5

    11Hz +18.0

    12.5Hz +16.5

    14Hz +13.5

    16Hz +11.5

    19Hz +8.0

    20Hz +7.5

    22Hz +6.5

    25Hz +5.0

    28Hz +4.0

    31.5Hz +3.0

    36Hz +2.5

    40Hz +2.5

    45Hz +2.0

    50Hz +1.5

    56Hz +1.5

    63Hz +1.5

    71Hz +1.5

    80Hz +1.5

    89Hz +1.5

    100Hz +2.0

    111Hz +1.0

    125Hz +0.5

    142.5Hz +0.5

    160Hz -0.5

    200Hz -0.5

    250Hz +0.5

    315Hz -0.5

    400Hz 0.0

    500Hz -0.5

    630Hz 0.0

    800Hz 0.0

    1.0KHz 0.0

    1.25Khz 0.0

    1.6KHz -0.5

    2.0Khz -1.5

    2.5Khz -1.5

    3.15Khz -1.5

    4.0KHz -2.0

    5.0KHz -2.0

    6.3KHz -2.0

    8.0KHz -2.0

    10Khz -1.0

    12.5KHz +0.5

    16KHz 0.0

    20KHz +1.0

    brucek
     
  6. Mark Guidry

    Mark Guidry Stunt Coordinator

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    Ok let me make sure I have this right. I take the trusty RS meter and I sit in the sweet spot. Put the reciever to the referenc volume that I used to calibrate all the speakers to 75 db's. Then I take a calibration disc and have it play all the seperate test tones from 16hz on up. I look at the meter on each Hz. level and see what it says...then lets say on 16hz I add 11.5 db's to it to get the actual #? Is this right or am I WAY off?

    Thanks

    Mark
     
  7. Steve Stogel

    Steve Stogel Supporting Actor

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    You're right about the measurement example you used (16Hz), but I wouldn't calibrate to reference with, say, VE or Avia and then pop in a test CD. I used Stryke's test CD, and if I had my receiver volume where I do to get reference from DVD's, I shudder to think what may have happened. Stryke's CD has a 1KHz test tone (Track 1), and you can use that for calibration, I suppose. Then you do as you stated and make the corrections for the given frequencies. If you just want to see how loud your sub will go, you can just slowly crank it up with the test tones (watch those really low tones, however) and see what you get. You are correct on how to use the "correction" values, though.

    Steve

    P.S. I believe it has something to do with the microphone on the RS SPL meter. It rolls off pretty bad, as you can see from the correction values.
     
  8. Mark Guidry

    Mark Guidry Stunt Coordinator

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    Ahh ok now I see...so I re-calibrat the sub with the first tone on a test CD and then I go from there...now after that is done I could (if I had one) use an EQ to try to get the values the same for each freq. (is that what they mean by flat responce) right? Then after that would I want to re-calibrat the sub volume back to the way it was before with the rest of the speakers??
     
  9. Dustin B

    Dustin B Producer

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    Correct. But remember, every 3dB increase in output requires a doubling of input power. So taming peaks it completely ok with an EQ. However, raising valleys kills your systems headroom.
     
  10. Kevin C Brown

    Kevin C Brown Producer

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    The correction numbers are a function of:

    1) non-flat response by the mike in the meter

    2) the C weighting scale

    But no one seems to know what the relative influence of either is.

    The C weighting scale "adjusts" for the perception of how people hear. Ears are less sensitive to low freqs than higher. Hence, note the increase in the correction numbers as the freq drops...
     

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