# Analog RS SPL meter correction table



## costanza (Feb 24, 2009)

I was looking for the table on the download page but got "no results for my search". Can anyone help? Supposedly (from reading a post here) the table here is supposed to be more accurate (relatively speaking) than those found elsewhere. Thanks!


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## EarlK (Jan 1, 2010)

Perhaps you're simply confusing the term, a "meter correction table" with a meter calibration file .

Radio Shack ( generic ) calibration files are found on the  *Downloads Page .*

:sn:


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## costanza (Feb 24, 2009)

Thanks! Wow. It's down 17 db at 20 hz?!!!


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## Wayne A. Pflughaupt (Apr 13, 2006)

Keep in mind that budget Class 3 sound level meters (SLM) like the one in question were never intended for measuring broadband frequency response. They are designed for measuring _noise levels,_ and as such filter response as either A or C weighting. As you can see from the graphs below, C weighting begins rolling out below ~50 Hz. So it’s normal for the meter set for C weighting to be significantly attenuated at 20 Hz. 










*A Weighted Curve









C Weighted Curve*​

The weighting filters are relevant for different situations that might be found in noise surveys, which is what SLMs are typically used for. For example, A weighting favors the frequency range that can cause hearing damage at high levels, and as such is commonly used for measuring workplace noise levels for complying with government safety standards. Broader-band C-weighting would be useful for say, determining the noise levels from the HVAC system in an auditorium where orchestras might perform, or in a recording studio to gauge the effectiveness of sound proofing.

If you’re using REW there’s no good reason or need for the compensation figures. They’re only useful for manually graphing frequency response using sine wave signals.

Regards,
Wayne


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