If your Radio Shack meter is Analog, this is a general concensis on calibration:

10hz.....+20.0db
12.5h....+16.5db
16hz.....+11.5db
20hz.......+7.5db
25hz.......+5.0db
31.5hz....+3.0db
40hz.......+2.5db
50hz.......+1.5db
63hz.......+1.5db
80hz.......+1.5db
100hz.....+2.0db
125hz.....+0.5db
160hz......-0.5db
200hz......-0.5db
250hz.....+0.5db
315hz......-0.5db
400hz.......0.0db
500hz......-0.5db
630hz.......0.0db
800hz.......0.0db
1k.....…....0.0db
1.25k..…..0.0db
1.6k.........-0.5db
2k............-1.5db
2.5k.........-1.5db
3.15k.......-1.5db
4k............-2.0db
5k............-2.0db
6.3k.........-2.0db
8k............-2.0db
10k..........-1.0db
12.5k......+0.5db
16k.....…..0.0db
20k.........+1.0db