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Note:

These numbers should be ADDED to the readings from the Radio Shack SPL meter.
Negative numbers will subtract of course.

The first column shows Frequency.

The second column shows the actual theoretical C-weighting curve .

The third column uses the C-weighting curve in the bass and My corrections for My meter in the treble.  I compared My measurements of my Hivi RT2's using Pink Noise and 1/3 octave Warbled Sine Waves to measurements from the LMS system at my friend's speaker company.  Hence the square baffle to fit their test rig.  I did get slightly different values for the Pink noise and warbled sine waves so I have printed the corrections for the Warbled Sine Waves as I believe they are more accurate (with less overlap) than those for Pink Noise.  Actually, these corrections aren't too terribly different than the HTF corrections except for more correction in the upper treble (which is also hinted at in the correction curves in the meter's booklet).  Also, I think the HTF corrections in the bass are a little excessive, so I just stuck to the normal C-weighting curve values.

The forth column uses the Home Theater Forum's measured corrections for Their meter in both the Bass and in the Treble.

IMPORTANT!!!!!!
Keep in mind that MY corrections apply to MY meter and HTF's correction applies to THEIR meter, and that the curves in the RS sound level meter booklet isn't exact for any meter.  But it is a relief to see that my curves and HTF's curves don't vary too much.  I guess this shows that at least the HTF corrections are more acceptable than the printed curves in the booklet if perhaps a bit "optimistic" in the bass corrections.
 
FREQUENCY
ACTUAL THEORETICAL C-weighting Curve (dB)
 C-weighting  Correction in the Bass
and MY ADJUSTED
RS Corrections in the Treble
(dB)		 HTF's Measured Corrections
(dB)
5.0
 24.9
 -
 -
6.3
 21.2
 -
 -
8.0
 17.6
 -
 -
10.0
14.3
14.3
20
12.6
11.2
11.2
16.5
15.9
8.5
8.5
11.5
20.0
6.2
6.2
7.5
25.2
4.4
4.4
5
31.7
3
3
3
40.0
2
2
2.5
50.4
1.3
1.3
1.5
63.5
0.8
0.8
1.5
80.0
0.5
0.5
1.5
100.8
0.3
0.3
2
127.0
0.2
0.2
0.5
160.0
0.1
0.1
-0.5
201.6
0
0
-0.5
254.0
0
0
0.5
320.0
0
0
-0.5
403.2
0
0
0
508.0
0
0
-0.5
640.0
0
0
0
806.3
0
0
0
1015.9
0
0
0
1280.0
0
0
0
1612.7
0.1
0
-0.5
2031.9
0.2
-0.5
-1.5
2560.0
0.3
-2
-1.5
3225.4
0.5
-0.5
-1.5
4063.7
0.8
1
-2
5120.0
1.3
-1
-2
6450.8
2
-1.5
-2
8127.5
3
-1
-2
10240.0
4.4
-0.5
-1
12901.6
6.2
2.5
0.5
16255.0
8.5
6.5
0
20480.0
11.2
8
1


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