REW, newrsdigital.cal, and c-weighting question

[Dent]

When using REW with my RS digital SPL meter I also load the newrsdigital.cal correction file which I understand has correction values for 10 Hz up to 105 Hz. Do I also enable "compensate for c-weighting" in the REW program because whether I do or not affects measurements of frequencies from 105 Hz and higher. Again it had been noted before that the RS analog meter's RCA output is c-weighted compensated but there was never an exact consensus whether the RS digital meter's RCA output was c-weighted or unweighted. At the AVS forum, a poster claimed that it was unweighted but others begged to differ. Now that we have analog and digital meters that have been tested, what is the verdict with respect to the c-weighting output or not because, again, it does affect the frequencies above 105 Hz which the new calibration files do not compensate for.

[brucek]

Do I also enable "compensate for c-weighting" in the REW program

Yes. This allows REW to create the c-weighted calibration data outside the frequency limits of the loaded calibration file (which in this case is everything above above 105Hz).....

brucek

[Dent]

But, does the RS digital (as opposed to the analog) SPL meter's RCA output send out a c-weighted or unweighted signal. That is the big question that has never been definitively answered and/or proven one way or the other. And that answer will affect the answer of whether "compensate for c-weighted" should be checked or unchecked in REW.

[brucek]

does the RS digital (as opposed to the analog) SPL meter's RCA output send out a c-weighted or unweighted signal.

Doesn't matter. What is important is that we set the switch on the meter itself to c-weight. The outputs of all three meters are not a perfect track of that desired c-standard, so we compensate for the inadequacies with a cal file in REW to force the resulting graph to be flat.

Our cal files compensate in the area of concern from 10Hz to about 105Hz where the meters deviate from the standard. After that they all are fairly accurate and we want to use the regular c-weight file in REW to take over, so we 'check the box.

brucek

[Sonnie]

I don't see where it really matters one way or another since there is not a lot of adjustment from 100hz to 200hz on c-weighting...


20 -6.2
25 -4.4
31.5 -3.0
40 -2.0
50 -1.3
63 -0.8
80 -0.5
100 -0.3
125 -0.2
160 -0.1
200 0.0
250 0.0
315 0.0
400 0.0
500 0.0
630 0.0
800 0.0
1000 0.0
1250 0.0
1600 -0.1
2000 -0.2
2500 -0.3
3150 -0.5
4000 -0.8
5000 -1.3
6300 -2.0
8000 -3.0
10000 -4.3
12500 -6.2
16000 -8.5
20000 -11.2

[Dent]

Oh, ok Sonnie,

I didn't know what the c-weighting values were in that 100 to 200 Hz area. The 10000 to 20000 Hz area sure affects things a lot though.

[Sonnie]

Yeah... the RS meters are wicked when they get past 10khz. If I were doing full range measurements I'd probably try to get a better mic. My ECM is pretty flat out to 46khz.