Hi,

There is no shortage of correction maps for the Radio Shack SPL meter which, you may have noticed, looks very similar to our own and, as a matter of fact, behaves similarly as well.

Here's a basic correction sheet:

http://www.danmarx.org/audioinnovation/rsmeter.html

 Here's another sheet, with instructions on the bottom on how to mod your meter to read more accurately in the lower frequencies:

http://forum.audiogon.com/cgi-bin/fr.pl?htech&983682086&openflup&1&4

 I should also point out that the SPL meter is not all that accurate above 10khz so I wouldn't use it to test the linearity of your speaker's response above that level otherwise you might end up thinking you have malfunctioning tweeters.