Quote Originally Posted by Woochifer
Try it out in a different location and use a wider range of frequencies. Room effects can boost the db readings at specific frequencies by 15 db or more. Also, corner placement will also reinforce the bass and the difference between a corner versus midwall placement can be huge.

Also, you mention in your post that you are getting this measurement at 40 Hz with a hip hop CD? First off, with just the RS SPL meter, you can only see what the decibel reading is, not what frequency it occurs. Also, with a music disc, you're only getting peak level readings at those high levels. The valid way to do a subwoofer test is to use a wideband test tone to get the overall output, and test tones to measure the output at specific frequencies. Keep in mind that most people on this board who post their subwoofer measurements are posting what the sub can SUSTAIN, not just the momentary bursts.
Hum...I have a SPL test disc that has 20~99Hz constant sinewave and the SPL meter is brand new used about twice, never miscared for. Watch...I'll tape it and post it on the net when I get back from class.