There are many examples of tests between calibrated measurement mics and the Radio Shack meters. They tend to be inaccurate above the 3KHz area. You're far better off with an SPL meter such as the Galaxy CM-140 (we supply the calibration file for it also).Does that mean that the 33-2050 is not providing the correct 'C' weighting characteristic?
If the Radio Shack meter complied with the C-Weight curve it would not require a calibration file to be used with REW, since REW has a C-Weight checkbox that would render the meter flat. Unforunately, this isn't the case. So, we developed a calibration file that replaces the C-Weight checkbox to render the Radio Shack meter flat over its limits. The limits of the file are from 7hz to 200Hz. After 200Hz the RS meters are fairly accurate up to ~3KHz. The file extends to 7Hz, but seriously we only offered that low value after repeated requests to provide a rough approximation. We tested mutiple RS meters in the development of the cal files and in my opinion they should only be used to about 15Hz. Below that the correction is usually down in the noise level and the results can't be trusted.So, are the correction figures (shown in this table) supposed to ensure that the 33-2050 complies with the 'C' weighting curve or ensure a flat response from 10Hz to 20kHz?
The meter.cal file over-rides the portion of the C-Weight curve (if checked) over the limits of the meter file. So, if the file extended from 10Hz-200Hz and the C-Weight box was checked, then those values would be over-riden and the C-Weight curve would extend out from there. But since the C-Weight correction is flat above 200Hz, and the fact that the Radio Shack meter shouldn't be used above ~3KHz, this is a long story to say that the answer to your question is, it doesn't matter.Should I should have the "C Weighted meter" checkbox UNchecked when using the cal file for a RS meter?