spl corection for non radio shack meters

Discussion in 'Speakers' started by rob hoinsky, Dec 9, 2004.

  1. rob hoinsky

    rob hoinsky Auditioning

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    i bought an American Recorder spl-8800 a while back thinking it was more accurate than the radio shack model that everyone uses, but i can't find any corrections for it. does anyone know where i might find them?

    thanx
     
  2. Edward J M

    Edward J M Cinematographer

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    Is the meter c-weighted?
     
  3. rob hoinsky

    rob hoinsky Auditioning

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    it can be a weighted or c weighted

    although i'm not sure where you're going with this...
     
  4. Edward J M

    Edward J M Cinematographer

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    Set the meter to C-weighted for FR sweeps or peak SPL monitoring.

    The A-weighted scale rolls off the response starting up around 500 Hz and is not useful for HT applications, only industrial noise monitoring.

    In the absence of specific correction factors for this particular meter, use the following CFs. They are the theoretical CFs for the C-weighted filter in your meter and will be quite sufficient for informal FR sweeps to identify and correct response anomalies, etc.

    Thank DougBW (Trilogy over at HT-SPOT) for these; he gave them to me about two years ago for my B&K SPL meter, which is also C-weighted.

    Regards,

    Ed

    FrequencyC-Weight
    10-14.33259693
    10.59463094-13.52968703
    11.22462048-12.74595335
    11.89207115-11.98268094
    12.5992105-11.24113838
    13.34839854-10.52255777
    14.14213562-9.828113197
    14.98307077-9.158898305
    15.87401052-8.515903684
    16.81792831-7.899994991
    17.81797436-7.311892737
    18.87748625-6.752154684
    20-6.221161728
    21.18926189-5.719108023
    22.44924097-5.24599587
    23.7841423-4.801635653
    25.198421-4.38565084
    26.69679708-3.997487754
    28.28427125-3.6364296
    29.96614154-3.30161399
    31.74802104-2.992053117
    33.63585661-2.706655603
    35.63594873-2.444249093
    37.75497251-2.203602722
    40-1.983448665
    42.37852377-1.782502185
    44.89848193-1.599479687
    47.5682846-1.43311451
    50.396842-1.282170279
    53.39359417-1.145451828
    56.56854249-1.021813749
    59.93228308-0.910166743
    63.49604208-0.809481987
    67.27171322-0.718793751
    71.27189745-0.63720053
    75.50994501-0.563864932
    80-0.498012574
    84.75704755-0.438930194
    89.79696386-0.385963182
    95.1365692-0.338512687
    100.793684-0.296032457
    106.7871883-0.258025523
    113.137085-0.224040813
    119.8645662-0.193669799
    126.9920842-0.1665432
    134.5434264-0.142327811
    142.5437949-0.12072348
    151.01989-0.101460247
    160-0.08429567
     
  5. rob hoinsky

    rob hoinsky Auditioning

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    thank you and thank you doug

    a little confusion, are those all subtraction?
     
  6. Craig Morris

    Craig Morris Stunt Coordinator

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    This is from my Revel B15 LFO Software .ini file. It includes the corrections for Radio Shack Analog and Digital... and also lists the following for "other".


    [Other "C-Weighted" Sound Level Meter]
    20=6.2
    21=5.7
    22=5.3
    24=4.9
    25=4.4
    27=4.0
    28=3.7
    30=3.3
    32=3.0
    34=2.8
    36=2.5
    38=2.2
    40=2.0
    43=1.8
    45=1.6
    48=1.4
    50=1.3
    53=1.2
    56=1.0
    60=0.9
    63=0.8
    67=0.7
    71=0.6
    75=0.6
    80=0.5
    95=0.4
    90=0.4
    95=0.3
    100=0.3
     
  7. Edward J M

    Edward J M Cinematographer

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    Yes, that's how far low (hence the negative) the meter will read at a given frequency.

    So you ADD that amount to the meter reading to obtain the actual SPL.

    So at 20 cycles, a c-weighted SPL meter will be reading about 6.2 dB low. So if the meter reads 80 dB, the actual sound pressure is 86 dB. And so forth for all the other frequencies listed above.

    Regards,

    Ed



    Regards,

    Ed
     

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