I bought the digital one instead of the analog. It has a dial that adjusts the frequency it looks for. The range is 60-120 hz, if I remember correctly, and it goes by incriments of 10 hz. I don't know the decibel range that this works in. I'm not sure if the 60 hz range will check for everything below 65 hz or just 55-65 hz. I'll check on that later.

I did think of some way that might work. If I know the frequency being output, and the meter reads everything below 65 hz, I could just add the corrections like normal. If that doesn't work, I'll probably just throw a fit.